Frozen in Time: Permafrost and Engineering Problems 0784409897, 978-0-7844-0989-3

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Frozen in Time: Permafrost and Engineering Problems

S.W. Muller explaining the origin of ice wedges at a mining exposure on Goldstream Creek, Fairbanks, 1944

Frozen in Time: Permafrost and Engineering Problems By Siemon Wm. Muller Professor of Geology Stanford University Edited by Hugh M. French Frederick E. Nelson Sponsored by Technical Committee on Cold Regions Engineering

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Library of Congress Cataloging-in-Publication Data Frozen in time : permafrost and engineering problems / edited by Hugh M. French, Frederick E. Nelson ; sponsored by Technical Committee on Cold Regions Engineering. p. cm. Includes bibliographical references and index. ISBN 978-0-7844-0989-3 1. Frozen ground. 2. Civil engineering—Cold weather conditions. 3. Building-Cold weather conditions. I. French, Hugh M. II. Nelson, Frederick E. III. American Society of Civil Engineers. Technical Committee on Cold Regions Engineering. TA713.F788 2008 620 ' .411 ~dc22

2008020323

American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia, 20191-4400 www.pubs.asce.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, contracts, regulations, statutes, or any other legal document. ASCE makes no representation or warranty of any kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes no liability therefore. This information should not be used without first securing competent advice with respect to its suitability for any general or specific application. Anyone utilizing this information assumes all liability arising from such use, including but not limited to infringement of any patent or patents. ASCE and American Society of Civil Engineers—Registered in U.S. Patent and Trademark Office. Photocopies and reprints. You can obtain instant permission to photocopy ASCE publications by using ASCE's online permission service (http://pubs.asce.org/permissions/requests/). Requests for 100 copies or more should be submitted to the Reprints Department, Publications Division, ASCE, (address above); email: [email protected]. A reprint order form can be found at http://pubs.asce. org/support/reprints/. Copyright © 2008 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-0989-3 Manufactured in the United States of America.

I) E D I C A T I O N

It was with great pleasure that I am able to approve of, and sign off on, the publication of my father's last work. This manuscript certainly lived under the radar for many years. I knew that Dad was working on a manuscript for publication, but I had no idea of its status or location after his passing. My special thanks and appreciation go to Professors Hugh French and Frederick Nelson for undertaking the compiling and editing that was required to get this historical document and original graphics ready for publication. I would like to expand on some items in the biographical sketch of quite a remarkable man and his adventurous life. It started in Eastern Siberia, then an escape to China, passage from Shanghai to the United States by way of the steamship, "Golden State" of the Pacific Mail Steamship Line in the early 1920s. He followed his brother, Bill, to the University of Oregon where he entered as a sophomore based on an incredibly strong transcript from his high school in Vladivostok. While doing field studies for his Stanford Doctoral Dissertation in 1928, he discovered a fossilized Ichthyosaurus in Central Nevada. This site subsequently yielded more than 40 of the largest remains of this creature ever found in North America, some over 50 ft. long. His special interest in stratigraphy and paleontology led him to investigate the connections between North American geological formations with those of Europe. During a sabbatical in Germany in 1937-38, he started this research, but Hitler sent him home before he could complete it. During 1956-57 he returned to continue his research, but this time he was interrupted by the Hungarian Revolution and the call by the U.S. State Department to interview and help place academic refugees. During World War Two, Dad served his country with the United States Geological Survey. First, he identified the location of strategic resources, and second, he completed a tour of duty as a Civilian Scientific Consultant assigned to the Alaska Division of the U.S. Air Transport Command under the command of Brigadier General Gaffney. Dad greatly appreciated the full support of the General and his staff during his work in Alaska. Eventually back at Stanford, Dad got back into what he loved most—teaching. He expected his students to achieve, and he enjoyed sharing in their success. All the former students with whom I have visited said they loved his classes and really appreciated him as a teacher and mentor. I want to extend a heartfelt thank you to Bucky Tart for his persistence in trying to find me. I was amused as he described the difficulty Professor French had experienced trying to track me. Obviously the contact in the Stanford Department was new and not aware of my relationship with Professor Muller, or that we have been contributing for many years to the Department of Earth Sciences in the form of v

Dad's memorabilia as well as annual financial gifts in Dad's name. The timing of my meeting with Bucky was amazing because, literally the day before he came to meet with my wife, Sherry, and I, when I authorized the publication of Dad's book, we had finalized an agreement with Stanford to fund the Professor "Si" Muller Memorial Fellowship for Graduate Geological Studies in the School of Earth Sciences at Stanford. I hope this book will be a significant contribution to the field of permafrost research. I'm sure Dad would be very pleased to know that time and need have finally caught up with his observations and research. ERIC MULLER Bow Washington February 24, 2008

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A C K N O W L E D G M E N T S We thank Bucky Tart and the Technical Committee on Cold Regions Engineering, American Society of Civil Engineers (TCCRE, ASCE), for agreeing to "thaw" this manuscript, which had remained, metaphorically, in a frozen state for so many years. We thank Eric Muller, Bow, WA, for graciously giving ASCE copyright of his late father's manuscript. Bequests to HMF from the late Roger J.E. Brown and the late Troy L. Péwé were also obvious prerequisites to publication of the manuscript. FEN wishes to acknowledge his late father, to whom he owes his interest in cold regions. Staff Sgt. Fred E. Nelson, a search-and-rescue pilot in the U.S. Army Air Force's Alaska Defense Command, spent more than two years during the later stages of World War II at the Galena airfield on the Yukon River. Siemon Muller is known to have visited the Galena installation during his 1943-^5 assignment to Alaska. It is intriguing to reflect on this crossing of paths at a small, remote outpost. August 2007 Hugh French, North Saanich, British Columbia, Canada Frederick E. Nelson, Newark, Delaware, USA

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I N T R O D U C T I O N Chance favors the prepared mind. —Louis Pasteur Serendipity plays a surprisingly important role in science (Roberts 1989). Together with the idiom "every dark cloud has a silver lining" and the figure of speech "being in the right place at the right time," serendipitous is an entirely appropriate way to describe Siemon William Muller's contributions to permafrost science. Muller is something of an enigma to many students of permafrost science. Although he wrote the highly regarded and authoritative first English-language book about permafrost (Muller 1947), he did not contribute to the field's primary literature. Few permafrost scientists are aware that Muller had a long and distinguished career in paleontology and stratigraphy. Although some know that his permafrost work arose from the necessity to avoid or correct military-engineering "SNAFUs" in Alaska and northern Canada during World War II, very few are aware that he maintained interest in the subject into the 1960s or that he had quietly compiled a massive review of Soviet and North American permafrost literature. The greatest mystery, however, is why he set that nearly completed manuscript aside shortly before retiring from university service. Muller has frequently been credited with having synthesized the term permafrost (for example, Brown 1970, Gary et al. 1972, Washburn 1980). Today, he is widely regarded as the father of North American permafrost science, almost entirely on the basis of the book resulting from his civilian service to the military during World War II (see Frontispiece and Plate I). This compilation of Russian-language literature, first distributed as a classified report under the title Permafrost or Permanently Frozen Ground and Related Engineering Problems (Muller 1943b), was nominally revised and reprinted in 1945, and appeared in 1947 in commercial book form under the imprimatur of J.W. Edwards of Ann Arbor, Michigan. The latter edition became the standard permafrost text in North America for more than 20 years and continues to be cited widely. Here, we present a nearly complete, previously unpublished (frozen) manuscript about permafrost. The book appears to have been completed during the early 1960s, near the end of Muller's career. From today's perspective, the book's comprehensive nature is unusual—it covers basic scientific knowledge about perennially frozen ground, the engineering problems associated with it, the geography of permafrost, related elements of landscape science and ecology, a smattering of periglacial geomorphology, and detailed treatment of the physics of frozen ground. There is, however, no doubt that frozen-ground engineering is the ultimate focus of the volume or that Muller intended it as an expansion of his earlier effort. Like its predecessor, many of its parts read like a "how-to" manual for engineering personnel working in pioneering or primitive circumstances. The wide-ranging nature of the topical matter contained in this book is in distinct contrast with most modern permafrost texts and monographs. Permafrost science IX

in North America has acquired a diffused structure, with specialist texts appearing regularly in various subfields, including frozen-ground engineering (such as Freitag and McFadden 1997, Andersland and Ladanyi 2004), geomorphology (French 2007), and soils (Kimble 2005). Volumes with wide topical range are, for the most part, limited to conference proceedings (such as Lewkowicz and Allard 1998, Phillips et al. 2003). The present volume provides a previously missing link between recent publications and the classic 1943 compilation by S.W. Muller.

S. W. Muller: A Biographical Sketch Siemon William ("Si") Muller was born in 1900 at Blagoveshchensk, Russia, near the border between Siberia and Manchuria. His Danish father, Wilhelm Muller, had come to Russia for work on the Trans-Siberian Railway's telegraph line and later became a teacher (Keen et al. 1971). Although details about Muller's early adulthood are spotty, the geographical and historical circumstances surrounding him assure us that it was tumultuous. At the time of the 1917 revolution Muller was enrolled in the Russian Naval Academy in Vladivostok. Over the next several years, its population swelled by refugees and the soldiers of five armies, the city descended into squalor and chaos. To the west, armored trains sparred along the Trans-Siberian Railway, the White government in Omsk fell, Admiral Kolchak was summarily executed at Irkutsk, and waves of atrocity and massacre engulfed Siberian cities (Connaughton 1990, Smele 1996). We do not know the precise date that Muller left Russia, but departure was certainly a rational act for someone who had been a cadet in the Czar's navy. Muller escaped to China and settled for a time in Shanghai, where he was employed by an American company and learned English. By 1921 he was in the United States, having worked his way across the Pacific as a ship's purser (Keen et al. 1971). He attended the University of Oregon, earning an A.B. in geology in 1927. This was followed by graduate work at Stanford University, where he received his M.A. in 1929 and his Ph.D. in 1930. Muller subsequently enjoyed a long and distinguished career of teaching and research at Stanford, first as instructor ( 1927-1930), then assistant professor ( 1930-1936), associate professor (1936-1941), professor (1941-1964), and professor emeritus (1965-1970). Described as a dynamic, engaging, and colorful teacher and field scientist, his research focused on the use of fossils to interpret the origins and history of stratified Paleozoic and Mesozoic rocks in the western United States (Keen et al. 1971, Page et al. 1975, Henry and Dutro 1993). With the renowned U.S. Geological Survey scientist Henry Ferguson, he worked out the complicated history of a large section of western Nevada. Muller was a talented, popular, and dedicated professor, and continued to teach well after his retirement. He received many professional honors and awards—among them, the status of Fellow in the Arctic Institute of North America (AÍNA 1958), a Triassic radiolarian (Loffa mulleri) named for him (Pessagno et al. 1979, 177), and two Guggenheim Fellowships. Muller also held several important professional offices, including councillor of the Geological Society of America, president of the Paleontological Society, and trustee of the California Academy of Science (Keen et al. 1971, Yochelson 1983). He died peacefully but unexpectedly in his sleep on September 9,1970. x

Müller s Contribution to Permafrost Science By 1941 Muller had achieved the rank of professor at a major research university, was recognized widely as an authority in the fields of Triassic paleontology and stratigraphy, and had begun to receive the honors due a scientist of his intellect and achievement. In 1942, however, the focus of his work was to change radically. Serendipity, silver linings, and geographical-historical convergence had found a focal point in Siemon Muller's prepared mind. Concerns in Washington and Ottawa about the vulnerability of Alaska to Japanese attack reached an extremely high level after the December 1941 debacle at Pearl Harbor. There was urgent need for an overland route to transport personnel and materiel to the Alaska Territory and to service the Northwest Staging Route, a chain of airfields through western Canada constructed in 1941 to ferry U.S. warplanes to Fairbanks where they were turned over to Soviet pilots. The Alean (now Alaska) Highway was authorized in February 1942. Construction of a 1,400 mile road between Dawson Creek, BC, and Delta Junction, AK, began the following month. Involving nearly 11,000 U.S. soldiers, a large contingent of Canadian troops, and 7,500 civilian workers, the road was one of the largest engineering projects undertaken in North America to that time. The project gained urgency with the Japanese incursion into the Aleutian Islands in June 1942. The initial "pioneer road" was opened to U.S. Army trucks in November 1942. This astonishingly rapid rate of construction was achieved by using extremely crude methods. Massive, 23-ton D-8 Caterpillar bulldozers indiscriminately cleared swaths through forest and muskeg, following immediately in the wake of survey crews who made routing decisions as they reconnoitered, often from the tops of trees. Inevitably, this mode of construction led to problems, the most serious of which involved thaw of ice-rich frozen ground. Because North Americans had little engineering experience in such terrain, problems were solved through trial and error. Experimentation with corduroy construction and application of insulating layers slowed progress considerably. The need for systematic assessment and construction methods soon became apparent, and the army turned to the U.S. Geological Survey for technical assistance. Siemon Muller was quickly identified as being almost uniquely qualified to assemble a technical guide for coping with "perpetually frozen ground." Speaking metaphorically, three dark clouds converged to produce a silver lining, which took form as Muller's contribution to North American permafrost science. The 1917-21 catastrophe in Siberia propelled Muller out of Russia, giving rise to his geological education. The 1941 naval disaster in Hawaii necessitated construction of the Alean Highway, and the naïve practices used initially in the road's construction led, in turn, to the need for precisely the set of linguistic and scientific skills in Muller's possession. Muller was truly "the right man in the right place at the right time," at least as far as wartime construction in the Arctic was concerned. As a field geologist, he was well versed in a broad spectrum of the earth sciences, including stratigraphy, structural geology, and field methods. The skill sets associated with these specialties XI

PLATE I. Photo of Siemon W. Muller in 1944, probably near Goldstream Creek, Fairbanks, AK, shown with Roy Earling, president of the U.S. Smelting, Refining, and Mining Company, and Fairbanks Exploration Company. Muller is wearing the uniform of a U.S. Army officer but with no insignia or rank; he was a civilian. Muller is looking unhappy because of the smelly, fetid, muck on his shoes. He was 44 years old at the time. Roy Earling (with belt and braces) was leading Muller and associates on a permafrost tour of the area. The sediments that enclose the ice wedges are part of the Goldstream Formation of Wisconsinan age (~ 120,000 to 10,000 years ago). The upper 1.5 m (above the ice wedges) is Holocene-age sediment (Ready Bullion Formation). This U.S. Army photo was autographed on the back and given to T.L. Péwé by S.W. Muller. The photo and caption details were supplied to HMF by TLP on December 5, 1996.

are, of course, also highly beneficial for those engaged in permafrost research. Muller was obviously linguistically well suited for translating the already extensive body of Soviet permafrost knowledge, at a time when most North American scientists spoke little Russian and had few direct contacts with Soviet scientists. Muller set to work compiling a practical summary of Soviet literature, using the resources of the Library of Congress and the USGS Library. Early in!943 a brief was issued for use by field engineers (Muller 1943a), and the full report (the distribution xn

of which was subject to military restrictions) was issued simultaneously (Muller 1943b). After assembling the volume, Muller conducted extensive field studies of military airbases and the Alean route, under the auspices of the Alaskan Division of the Air Transport Command. Toward the end of his service in Alaska he was accompanied on a lengthy traverse by the USGS scientists Robert F. Black, Robert E. Wallace, and Max Elias. As Wallace later put it, Muller "had done all that he could in the translation program, so the Air Force turned the [permafrost] program over to USGS to continue and to engage in new geologic and field studies to evaluate and understand [permafrost related] problems" (Wallace 1999, 21). Muller received a meritorious service award for his contributions to the armed forces, and was later awarded the Freedom Medal for his permafrost work (Keen et al. 1971). With the permafrost project completed, Muller returned to Stanford and resumed the paléontologie and stratigraphie work that constituted his primary interest. Although he taught a course on permafrost at Stanford and supervised a doctoral dissertation on the subject (Péwé 1953), his only postwar contributions to its literature were to commission a printing of the declassified military-engineering report (Muller 1947), and to publish an abstract concerned with permafrost (Muller 1946). Although the 1947 version of the report was printed privately and was not widely reviewed at the time,1 the book had tremendous influence on the development of North American permafrost science. It forms an accessible and comprehensive portal to early Russian-language literature and, therefore, to the elemental concepts of permafrost science and engineering. For this reason the book continues to be cited widely in English-language literature 60 years after its appearance in declassified form. It is used frequently as a definitive source for resolving terminological and conceptual questions and disputes (such as Burn 1998, van Everdingen 1998). Ironically, Muller's detour into permafrost science was to change the way in which he is perceived by posterity. Despite his legacy of accomplishment, leadership, and publication in paleontology and stratigraphy, the pamphlet describing the history of Stanford University's School of Earth Sciences commemorates Muller's contributions with a sidebar entitled "Siemon W. Muller and Permafrost" (Stanford School of Earth Sciences 1997). The same source makes only passing mention of his paleontological work. Page et al. (1975, 144) made the implicit suggestion that Muller experienced some frustration about the intrusion of permafrost into his main studies, noting that "demands stemming from his knowledge of permafrost kept diverting him long after the war ended, and rarely was he able to devote himself continuously to the paleontologic-stratigraphic-structural work that was dear to his heart." They suggested further that "from a purely scientific standpoint the digression [into permafrost studies] was rather tragic." Although we must admit to a certain bias in the matter, we assert that nothing could be farther from the truth.

The "Frozen Manuscript" Serendipity continued to affect Siemon Muller's permafrost work long after his passing. Largely through chance, both a frozen permafrost manuscript authored by 1

Black (1948) is the only book review we have been able to uncover. xiii

Muller and an unpublished professional review of it came into the possession of a single individual. The late professor Troy L. Péwé of Arizona State University was the only one of Muller's graduate students to specialize in permafrost. At the time of Muller's death in 1970, Péwé, himself a celebrated permafrost scientist, came into possession of many of Muller's files. In July 1996 Professor Péwé passed several unopened boxes containing books, numerous reprints, and a large number of original photographs to one of us (HMF). Contained within these materials was a typed manuscript totaling more than 700 pages, contained in two large loose-leaf binders. Careful reading indicated a text on permafrost that, clearly, was in the very advanced stages of submission to a publisher. Sixteen years previously, in 1980, HMF had acquired some of the research papers and reprints of the Canadian permafrost scientist, Roger J. E. Brown (National Research Council of Canada), who had died earlier that year. Contained in that collection was a 31-page typewritten report entitled "Review of Manuscript on Permafrost by S.W. Muller." The authors were G.H. Johnston and R.J.E. Brown. This undated review gave general comments, suggested a reorganized outline, and provided a detailed line-by-line review of an unknown manuscript. In 1980 it was unclear to HMF what text this review referred to, and it was filed away. By the time the Muller materials were catalogued by HMF, Hank Johnston had died. However, it was immediately apparent that the Brown-Johnston review related to the manuscript contained in the Muller materials that had been passed to HMF by Professor Péwé. One can speculate that Muller had sent the text to R. Leggett, Ph.D., then head of the Division of Building Research, National Research Council of Canada, who had then passed it to his two Canadian permafrost experts. The Johnson-Brown review also indicates the high esteem in which Muller regarded Canadian permafrost research. It was also clear that the text was intended to update the 1947 edition of Muller's earlier review. This is mentioned explicitly in the preface of the present book. However, there is no date on the manuscript. Because the latest references date to 1962 and because there is no mention of any of the permafrost advances reported at the First International Conference on Permafrost, held at Purdue University, Lafayette, IN, in 1963, we believe the manuscript was completed by 1963. Why it remained in manuscript form from that date onwards until Professor Muller's death in 1970 remains a mystery. Although it is certain that Muller attended the 1963 permafrost conference (Building Research Advisory Board 1966, 562) there is no evidence that he contributed to the meeting's program. For unknown reason(s), he apparently chose to abandon the book project at about the time the conference was held.

Manuscript Contení and Structure From the viewpoint of permafrost science (Parts One and Two), there are several areas where the text indicates that Muller was significantly ahead of his time. First, Muller clearly understood the significance of moisture migration in freezing and frozen soils, and its relevance to frost heaving. The importance of Taber's early work (for example, Taber 1930) is clearly recognized but there is, in addition, xiv

detailed discussion of the work of Penner (1956, 1959) concerning ice segregation, as well as other papers published on this topic in the 1959-62 period. This book was written well before oil was discovered at Prudhoe Bay and prior to publication of the texts by Tsytovich (1973, translated 1975) and Johnston (1980). One is tempted to speculate about the impacts of Muller's treatise on engineering practice in northern North America in the 1970s, had the book been published in 1963. Second, Muller's deliberate use of the term active zone, rather than the more generally accepted term active layer, may be viewed, from the privileged position of history, as a sign that Muller was aware of the importance of conditions at the base of the active layer and the top of permafrost. In recent years, the concept of the transient layer has been introduced into the North American literature (Shur 1988, Shur et al. 2005) to explain the distribution of ground ice and the efficacy of certain active-layer processes and phenomena. Definition of the active layer continues to attract controversy (Burn 1998). Yet the nature of this so-called transient layer was well known to Russian permafrost scientists from the 1930s onwards, and Figure 1 clearly shows a layer that would be identified today as the transient layer. Interestingly, Muller indicated in a handwritten notation that he intended to either remove or rename this layer to conform to the more conventional wisdom of the day. One can speculate that the JohnstonBrown review was the reason for this intended modification to the text. Third, Muller was also ahead of his time, at least in the North American context, in his understanding of ground ice. For example, he introduces the Russian concepts of cryostructures and cryotextures in Part Two. These are more advanced than the descriptive and elementary classification of ground ice produced in Canada at about the same time (Pihlainen and Johnston 1963) and which became the basic North American approach for at least two decades. In Russia by contrast, details of the cryostratigraphic approach were first described in Moscow University textbooks from the mid 1960s onwards (such as Dostovalov and Kudryavtsev 1967, Kudryavtsev,1978, 304-316; see Melnikov and Spesivtsev 2000), and only slowly were cryostatigraphic concepts introduced into North America (such as Mackay 1974, Murtón and French 1994). Fourth, Muller was well aware of the "cryo" terminology proposed earlier by Bryan ( 1946) and writes, in general terms, about cryogenic processes. This terminology was largely rejected by the periglacial and geomorphological communities of the time, yet its utility was re-examined fairly recently (for example, ACGR 1988, van Everdingen 1998, Burn 1998). These discussions reflect an awareness of the unfrozen water that exists in permafrost and the idea that cry otic terminology could avoid some of the semantic pitfalls of the terms "frozen" and "unfrozen" (while, admittedly, creating other terminological problems). Today, Muller's explicit treatment of this problem in Chapter 1 predates, by at least a quarter-century, some of the more recent North American discussions of this topic. From the viewpoint of permafrost engineering (Part Three), the manuscript gives a useful description of the many relatively unsophisticated approaches that were being used by engineers in the 1950s. The discussion of highway construction, the avoidance of icings, and the problems associated with water supply are not only of historical interest but also contain useful examples of either the occurrence

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or prevention of permafrost-related problems. Surprisingly, the manuscript pays relatively little attention to the problems posed by oil and gas exploration in permafrost terrain, although some of the terrain and environmental problems associated with the early exploratory drilling operations in NPR-4 (e.g., Fish Creek exploratory well; see Lawson et al., 1978) must have been clearly apparent by the early 1960s. Likewise, the use of permafrost as an archive of past climatic conditions is largely neglected except for brief mention of the preservation potential of Pleistocene mammal and Holocene archaeological remains. The state of knowledge about permafrost and the rudimentary instrumentation used to monitor it in North America in the early 1960s is also well illustrated in Part Three. Descriptions of the instrumentation and techniques used at the time, especially at the Fairbanks Permafrost Research site, illustrate the limitations under which early permafrost scientists and engineers conducted their work. The methods used to document frost heave and ground temperatures are of special interest. For example, the swellometer instrumentation is a clear forerunner of the telescoping tubes developed in the mid 1970s (Mackay 1979) and subsequently used widely. Although precision thermistors and data loggers have long since replaced the thermometers and drum-chart recording devices illustrated in Muller's manuscript, it is fascinating to reflect on how this manuscript brings a 150-year era to a close with its review of the use of glass thermometers to measure permafrost temperatures.

Terminology As a palaeontologist and taxonomist, Muller naturally had strong interests in classification and terminology. Page et al. (1975,143) observed that he "had Teutonic instincts for logic, order, and consistency." Such concerns, reflected in publications with titles that include "Stratigraphie Terminology" (Schenck and Muller 1941) and "Procedure in Taxonomy" (Keen and Muller 1949), are manifested clearly in the present volume. Included in the book is a terminology section that ran to 25 manuscript pages and contains a spirited rejoinder to Kirk Bryan's (1946) criticisms of Muller's (1943b) earlier terminological suggestions. We speculate that Muller's concern for concise, unambiguous definitions as a precursor to substantive discussion is also responsible for the unusual placement of a 60-plus page glossary in the early part of the manuscript (we have removed the glossary to an appendix in the interests of continuity and readability). The section on terminology is also interesting in that it gives insight into the bureaucratic workings of a Soviet scientific committee, whose recommendations Muller savages. While it is clear, from Muller's discussion of the deliberations of the commission set up in the Institute of Permafrost in Moscow in the mid 1950s, that individuals such as M.I. Sumgin, S.V. Obruchev, and N.A. Tsytovich were regarded as authorities and "elder statesmen," it is less clear how the next generation of Russian permafrost scientists, such as V.A. Kudryavtsev, P.I. Melnikov, P.F. Shvetsov, and B.N. Dostovalov, emerged to lead the Soviet hierarchy in the 1960s. A minor etymological mystery has been solved with the discovery of this manuscript. Muller has received credit from many quarters (including Oxford xvi

English Dictionary) for having coined2 the term permafrost by contracting the English-language phrase permanently frozen ground. This assumption is based on the following passage from Muller's earlier book: The phenomenon of permanently frozen ground is also known as "permanently frozen soil" or "everfrozen soil", but it is believed that the expression "permanently frozen ground" is the most appropriate... the expression "permanently frozen ground", however, is too long and cumbersome, and for this reason a shorter term, permafrost, is proposed as an alternative. (Muller 1943, p. 3) In 1989 the linguists Victor V. Kabakchi (Leningrad Pedagogical Institute) and Ronald R. Butters (Duke University) published a short paper in which they noted that "the word permafrost is constructed exactly like the technical Russian term for the same phenomenon, vechnaya merzlota 'eternal frost'." Kabakchi and Butters (1989, p. 287) suggested that this similarity constitutes evidence that the term is a loan translation (a word-for-word or element-by-element translation from one language to another) and asked rhetorically whether "the American Siemon Muller" had created the term himself or borrowed it from Sumgin (1927). Their paper concludes: As a blend of English and Latin morphemes, permafrost looks acultural—apart of the international scientific vocabulary based predominantly on Latin, Greek, and English...however, it appears that dictionary makers may have overlooked the ultimate Russian origins of the term. Kabakchi and Butters can be forgiven for not realizing Muller 's Russian origins— in fact, their inference is impressive in light of Muller's distinctly non-Russian name. The Preface to the 1962 manuscript contains clear evidence in support of their hypothesis that Muller had calqued the term. Here, Muller argues vehemently against a Soviet committee's recommendation to abandon the term vechnaya merzlota, and equates the Russian and English forms explicitly: To those who will be reading current Russian works on permafrost it should be pointed out that the old term Vechnaya merzlota (eternally frozen ground-permafrost) is now officially replaced by mnogoletnyaya merzlota (perennially frozen ground)—a change hardly warranted, for after all, what on this earth is actually "eternal" or "permanent"?

2

The word coined is used in an astonishingly long list of publications citing Muller as the originator of the term permafrost. xvii

The Edited Version As editors, we agreed with the general comment made by Johnston and Brown that the text needed "...considerable editing and re-organization." We have attempted to follow through on this recommendation. We have edited Professor Muller's manuscript and eliminated various inconsistencies. We have adopted many of the comments made in the Johnston-Brown review but, as far as possible, have left the manuscript in its original form. We have kept the order of the various sections but, whereas Johnston and Brown suggested reorganization into just two parts (Part I: Permafrost: Fundamental Considerations and Part II: Permafrost: Engineering Considerations), we have subdivided the manuscript into three parts: Part One: Introduction, Part Two: Permafrost Science, and Part Three: Permafrost Engineering. Where sections of the original manuscript have been omitted, or paraphrased, these are indicated in the text in bold type. A small number of references cited in the original manuscript were not included in the bibliography, and many references in the bibliography were not cited in the text. We were able to locate most of the missing references through bibliographic resources such as Arctic Bibliography. Literature cited in the text was consolidated to create a new References section. We removed a Glossary from its original position in Part One of the manuscript and reinserted it as Appendix II. All figures are in their original format. None have been removed. However, we have grouped the figures more efficiently and the total number of figures is now 94 rather than the 144 in the original manuscript. One figure (Figure 1) had been marked up by Muller to indicate that it was to be revised. We also support Johnston and Brown in their comments concerning some of the terminology used by Muller. Four of the more fundamental concerns are restated here. First, Muller's use and vehement defence of the term permanently frozen ground has not met with general acceptance in North America. Brown and Johnston pointed out that Russians are very careful in their use of this word; their term for "perennial" (mngoletnyayd) is quite exact. We have left the word permanently in the text when Muller refers to permafrost, but readers should interpret this to refer to perennially frozen ground. Second, Muller's use of the term active zone rather than active layer has also not received wide usage in North America. However, for historical accuracy, and for reasons explained below, we have also retained this term in the text. Third, the terms rock, soil, ground, and grounds are used loosely throughout the manuscript. Muller appears to have translated the Russian term for rock literally. This word is also frequently used to describe soil. In our editing, we have attempted to eliminate this confusion. Fourth, the meaning and uses of the words "north," "Arctic," and "Subarctic" were unclear. In particular, Muller appears to have applied the terms "Arctic" and "Subarctic" only to tundra areas. We have modified the text to make these terms more explicit. The manuscript, like the earlier one that it was intended to replace, places much of its focus on the engineering problems associated with permafrost conditions. Thus, the text pays scant attention to the geomorphological paradigms of the early 1960s, namely periglacial geomorphology in Europe and the quantitative (process) xvni

revolution in fluvial geomorphology in North America. This was a time when "periglacial fever" was sweeping Europe as a branch of a largely geographically based climatic geomorphology, while in North America Davisian geomorphology was being replaced by the quantitative, process-oriented studies of Leopold, Schumm, Hack,3 and others at USGS. Muller's manuscript makes no mention of these trends but does recognize the important geotechnical advances being made in Canada and Scandinavia about ground freezing and frost heaving. The manuscript is also firmly oriented toward the lessons that central and northern Alaska can learn from the Siberian taiga. Thus, there is little discussion of the extreme high northern latitudes, alpine (mountain) permafrost, and the montane permafrost of central Asia and Tibet. Pleistocene-age permafrost is not discussed (and was largely unknown to North American scientists in the early 1960s) and relict Pleistocene permafrost phenomena in the mid-latitudes get no passing mention. Undoubtedly, the main difference between the present manuscript and that printed in 1943 is the expanded section on permafrost science (Part Two). We have maintained this expanded text, but with two exceptions. First, a significant part of the expanded text concerned a discussion about the nature and growth of vegetation and its influence upon, or reflection of, permafrost conditions in the Russian subarctic and tundra regions. Much material appeared to be based upon a text by Grigor'yev (1956). Because of its rambling and sometimes highly detailed nature, we have reduced or paraphrased the sections dealing with plant growth at low temperature, and on cryogenic processes. But it is to Professor Muller's credit that, today, many permafrost scientists would agree with the implication that the role of vegetation is both complex and fundamental and that cryobotany, for want of a better term, is an increasingly important field of study (for example, Gilichinsky etal. 1995). Second, several expanded sections deal with cryogenic weathering. Pagination in the original manuscript indicates clearly that this material was inserted at a late stage. It is also problematic. For example, the manuscript presents a seemingly uncritical acceptance of freeze-thaw as the dominant mechanical weathering process. Yet, this is at variance with a subsequent inclusion, also inserted at a late stage in manuscript preparation, entitled "Physico-chemical and biochemical processes in frozen ground." This poorly focused section has been omitted because it has the appearance of a rough draft. In fact, the manuscript at this point indicates that Muller's thoughts on weathering were in a state of flux and uncertainty. Part Three is largely unaltered from the manuscript copy. In preparing the manuscript for final publication, we used aperiod style manual, the fifth edition of Suggestions to Authors of the Reports of the United States Geological Survey (USGS 1958), a volume Muller undoubtedly had on his shelf at the time the book was written. We have, however, left some of the text's peculiarities intact, foremost among them the mixed use of metric and English units of measurement. We speculate that this oddity derives from a notion that it is appropriate to report items in 3 We note in passing that USGS geologist J. T. Hack, widely recognized subsequently for his theoretical work in geomorphology, was a reviewer of the 1943 report (Muller, 1943b, p. 2).

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the units used in the original publications. There is little doubt, however, that it was intentional—none of the many handwritten annotations on the original manuscript involved unit conversions, and mixed usage was also employed in Muller's earlier permafrost book.

We believe, for several reasons, that Muller's manuscript deserves publication. •

We regard the text as an important historical document because it was clearly intended by Professor Muller to be an update to his 1943 text. Because the earlier version is now regarded as the first book on permafrost written in North America, it is fitting to close the circle on Professor Muller after more than 50 years and make his revision available at the time of the Ninth International Conference on Permafrost in Fairbanks, AK, in 2008.

•

We maintain that the text contains information and examples that are still relevant today, nearly half a century after the manuscript was written. However, our job as editors is not to duplicate Muller's work by summarizing this information in our introduction; instead, we urge all those interested in the engineering aspects of permafrost terrain to read Professor Muller's words, examine the numerous photographs, and to reflect upon the advances and, in some instances, the relative lack of advances, in engineering science that have characterized the last 50 years.

•

We firmly believe the text was ahead of its time in certain respects and, if published in 1963, would have significantly advanced North American understanding of permafrost science and engineering. Our assessment is that the comprehensive grasp of permafrost science revealed in this manuscript was only superseded in North America in the early 1980s (that is, after construction of the Trans-Alaska Pipeline and after the 1978 (Edmonton, Canada) and 1983 (Fairbanks, Alaska) international permafrost conferences.

•

The manuscript provides a rare opportunity to compare the states of Englishand Russian-language permafrost science at a time when relations between North America and the USSR were difficult and hampered by suspicion.

Serendipity... and Its Inverse Si Muller's engagement with permafrost in the early 1940s was a lucky accident that provided major benefits to the Allied war effort. Alaskans and northern Canadians have benefited immeasurably from the well engineered infrastructure made possible by the knowledge Muller extracted from Russian literature. By consolidating the information about frozen ground he found in linguistically inaccessible sources, Muller also facilitated rapid postwar progress in North American permafrost science.

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As noted in the previous section, however, the fact that the current manuscript did not achieve timely publication is an unlucky circumstance. It is only possible to speculate about why Muller, in effect, turned his nearly completed manuscript into a time capsule. His bibliography (Page et al. 1975, 145-146) shows no upswing in publication that might indicate involvement in competing projects during the early 1960s. Perhaps his experiences at the first International Conference on Permafrost in 1963, which would have provided obvious indications of increasing specialization in the subject, led him to conclude that the time for a general text such as his had passed. Another possibility involves the fact that, by the time the manuscript was completed, some areas of permafrost science (including cold-regions engineering) had begun to look like applied mathematics and physics—a traditional field geologist like Muller may have felt that the engineering branch of the subject had moved beyond his interests, or demanded skills he did not possess. Another conjecture involves the manuscript's extensive treatment of pioneer-style logistics and traditional methods of measurement, which indicate that it may have been written over a long period of time. Muller might have concluded that the rapid pace of technological change, in combination with his impending retirement, made extensive revision too daunting a task. Or, Muller may simply have lost interest in the project. Whatever the reason(s) for the abandonment, it was indeed a set of lucky accidents that finally brought the volume to the publication stage. Better late than never. We say no more and leave the reader to judge the utility of Muller's text, and to reflect upon the impact it might have had on the growth of permafrost science and engineering in North America had it been published in the early 1960s.

References ACGR (Associate Committee on Geotechnical Research) (1988). Glossary of permafrost and related ground ice terms. Permafrost Subcommittee, National Research Council of Canada, Ottawa, Technical Memorandum 142, 156pp. Andersland, O.B. and Ladanyi, B. (2004). Frozen ground engineering. Hoboken, NJ: John Wiley & Sons and American Society of Civil Engineers, 362 pp. Arctic Institute of North America (1958). Election of Fellows. Arctic, 11, 256. Black, R.F. ( 1948). Permafrost or permanently frozen ground and related engineering problems (book review). Geographical Review, 38: 686-687. Brown, R.J.E. (1970). Permafrost in Canada. University of Toronto Press, Toronto, 234 pp. Bryan, K., (1946). Cryopedology - the study of frozen ground and intensive frost action with suggestions on nomenclature. American Journal of Science, 244, 622-642. Building Research Advisory Board (1966). Permafrost International Conference. National Academy of Sciences—National Research Council, Publication No. 1287, Washington, DC, 563 pp.

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Burn, C.R., (1998).The active layer: two contrasting definitions. Permafrost and Periglacial Processes, 9, 411-416. Connaughton, R.M. (1990). The Republic of the Ushakovka: Admiral Kolchak and the Allied intervention in Siberia 1918-20. Routledge, London, 193 pp. Dostovalov, B.N., Kudryavtsev, V.A., 1967. Obshcheye merzlotovedenya (General permafrost science). Moscow State University, 403 pp. (in Russian), van Everdingen, R.O. (ed., 1998). Multi-language glossary of permafrost and related ground-ice terms, version 2. International Permafrost Association/ Arctic Institute of North America, Calgary, Alberta: University Printing Services, University of Calgary. French, H.M., (2007). The periglacial environment. John Wiley and Sons, Chichester, 458 pp. Freitag, D.R., and McFadden, T. (1997). Introduction to cold regions engineering. American Society of Civil Engineers Press, New York, 738 pp. Gary, M., McAfee, R. Jr., and Wolf, C.L. (eds., 1972). Glossary of Geology. American Geological Institute, Washington, DC, 805 pp. Gilichinsky, D., Wagener, S., Vishnevetskaya, T. A., (1995). Permafrost microbiology. Permafrost and Periglacial Processes, 6, 281-291. Henry, T.W. andDutro, J.T. Jr. (1993). Memorial: Mackenzie Gordon, Jr. (1913-1992). Journal of Paleontology, 67, 494-496. Johnston, G.H., ed., (1980). Permafrost: Engineering design and construction. John Wiley and Sons, New York, 340 pp. Johnston, G.H., Brown, R.J.E., (undated). Review of manuscript on permafrost by S. W. Muller. Ottawa: Division of Building Research, National Research Council, Canada. Unpublished internal report. Photocopy, 31 pp. Kabakchi, V.V. and Butters, R.R. (1989). Are permafrost and vernalization loan translations from Russian? American Speech, 64, 287-288. Keen, A.M., and Muller, S.W. (1949). Revision of Procedure in Taxonomy by E. T. Schenk and J. H. McMasters. Stanford University Press, Palo Alto, CA, 93 pp. Keen, A.M., Silberling, N J., and Page, B.M. (1971). Siemon William Muller (1900-1970). American Association of Petroleum Geologists Bulletin, 55, 133-134. Kimble, J.M., ed., (2004).Cryosols: Permafrost-affected soils. Springer-Verlag, Berlin, 726 pp. Kudryavtsev, V.A., (1978). Obshcheye merzlotovedenya (gyeokreologeya) (General permafrost science—geocryology). Moscow State University, 464 pp. (in Russian). Lawson, D.E., Brown, J., Everett, K.R., Johnson, A.W., Komarkova, V., Murray, B.M., Murray, D.F., Webber, P.J., (1978). Tundra disturbance and recovery following the 1949 exploratory drilling, Fish Creek, northern Alaska. U.S. Army CRREL, Hanover, New Hampshire, Report 78-28, 81pp. Lewkowicz, A.G., Allard, M., eds., (1998). Permafrost, Seventh International Conference, June 23-27, 1998, Yellowknife, Canada. Centre d'études nordiques, Université Laval, Nordicana 57, 1276 pp.

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Mackay, J.R., (1974).Reticulate ice veins in permafrost. Canadian Geotechnical Journal, 11,230-237. Mackay, J.R., (1979). Frost heave at ground temperatures below 0°C, Inuvik, Northwest territories. In: Current Research, Part A; Geological Survey of Canada, Paper 79-1 A, 403-405. Melnikov, V.P., Spesivtsev, V.l., (2000). Cryogenic formations in the Earth's lithosphère. Novosibirsk Scientific Publishing Center UIGGM, SB RAS Publishing House, 343 pp. (in Russian and English). Muller, S.W. (1943a). Brief on Special Report no. 62. Permafrost or permanently frozen ground, Prepared from U. S. Geological Survey Report. Mimeographed, 14 plates and 39 pp. Muller, S.W., (1943b). Permafrost or permanently frozen ground and related engineering problems. Special Report, Strategic Engineering Study no. 62. Intelligence Branch, Office of the Chief of Engineers, 136 pp. + 80 figs. Second printing, 1945, 230 pp. Muller, S.W. (1946). Permafrost and related engineering problems. American Association of Petroleum Geologists Bulletin, 30, 2089. Muller, S. W. ( 1947). Permafrost or permanently frozen ground and related engineering problems. J. W. Edwards, Inc., Ann Arbor, MI, 231 pp. Muller, S.W. (1983). Some field hints from an old top hand. Journal of Geological Education, 31, 36-37. Murtón, J.B., French, H.M., (1994). Cryostructures in permafrost, Tuktoyaktuk coastlands, western Arctic, Canada. Canadian Journal of Earth Sciences, 31,737-747. Page, B.M., Silberling, N.J., and Keen, A.M. (1975). Memorial to Siemon W. Muller 1900-1970. The Geological Society of America Memorials, 4, 142-146. Penner, E., (1956). Soil moisture movement during ice segregation. Highway Research Board, Bulletin 135, 109-118. Penner, E., (1959). The mechanics of frost heaving in soils. Highway Research Board, Bulletin 225, 1-13. Pessagno, E.A., Finch, W, and Abbot, P.L. (1979). Upper Triassic radiolaria from the San Hipólito Formation, Baja California. Micropaleontology 25, 160-197. Péwé, T.L. (1953). Geomorphology of the Fairbanks area, Alaska. Ph.D. Dissertation, Stanford University, 308 pp. Phillips, M., Springman, S.M., Aremson, L.U., eds., (2003). Permafrost, Proceedings of the Eighth International Conference on Permafrost, 21-25 July 2003, Zurich, Switzerland. Balkema, Lisse, 2 volumes, 1322 pp. Pihlainen, J.A., Johnston, G.H., (1963). Guide to a field description of permafrost. National Research Council, Associate Committee on Soil and Snow Mechanics, Technical Memorandum 79, 23 pp. Roberts, R.M. (1989). Serendipity: accidental discoveries in science. John Wiley & Sons, New York, 270 pp. Schenck, H.G. and Muller, S.W. (1941). Stratigraphie terminology. Geological Society of America Bulletin, 52, 1419-1426.

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Senneset, K. ed., (2000). Proceedings. International workshop on permafrost engineering, Longyearbyen, Svalbard, Norway, 18-21 June. Norwegian University of Science and Technology (NTNU)/ The University Courses on Svalbard (UNIS), 327 pp. Shur, Y., (1988). The upper horizon of permafrost soils. In: Senneset, K., ed., Permafrost, Proceedings, Fifth International Conference, 2-5 August, 1988, Tapir, Trondheim, Vol 1, 867-871. Shur, Y., Kinkel, K.M., Nelson, F.E., (2005). The transient layer: implications for geocryology and climate-change science. Permafrost and Periglacial Processes, 16, 5-18. Smele, J.D. (1996). Civil war in Siberia: the anti-Bolshevik Government of Admiral Kolchak, 1918-1920. Cambridge University Press, Cambridge, 759 pp. Stanford School of Earth Sciences (1997). Time Slices: a brief history of Earth Sciences at Stanford. Stanford School of Earth Sciences, Palo Alto, CA, 19pp. Sumgin, M.I. (1927). Vechnaya merzlota pochvy v predyelakh SSSR. (Permafrost within the confines of the USSR). Izd-vo Akademii nauk SSSR, MoscowLeningrad (in Russian). Taber, S., (1930). Frost heaving. Journal of Geology, 37, 428-461. Tsytovich, N.A., (1973). Mekhanika merzlykh gruntov (The mechanics of frozen ground).Vysshaya Shkola Press, Moscow, 446 pp. (in Russian). (English translation: Swinzow, G.K., Tschebotarioff, O.P., eds., 1975, Scripta/ McGraw Hill, New York, 426pp). USGS (1958). Suggestions to authors of the reports of the United States Geological Survey, Fifth Edition. U.S. Government Printing Office, Washington, DC, 255 pp. Wallace, R.E. (1999). Connections, the EERI Oral History Project: Robert E. Wallace (interviewed by Stanley Scott). Earthquake Engineering Research Institute, Oakland, CA, 186pp. Washburn, A.L. (1980). Geocryology: a survey of periglacial processes and environments. John Wiley & Sons, New York, 406 pp. Yochelson, E.L. (1983). The Paleontological Society: 75 years of presidents and presidential addresses. Journal of Paleontology, 57,1128-1134.

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Frozen in Time: Permafrost and Engineering Problems By Siemon Wm. Muller Professor of Geology Stanford University

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P R E F A C E

This book is an outgrowth of the compilation Permafrost or Permanently Frozen Ground and related Engineering Problems, which was prepared by the writer for the U.S. Army Engineers Corps in 1943, based chiefly on published Russian sources. That manual, with minor revisions based on the author's own first-hand study, was reissued by the Chief of Engineers, U.S. Army, in 1945 and was subsequently reprinted in book form in 1947, by arrangement with the Office of Technical Services, Department of Commerce, by J.W. Edwards, Inc. Much information on permafrost has been published during the past two decades in Russia and also in the United States and Canada. Significant advances were made in the evaluation of solar radiation upon the physical and biologic factors of the terrain. Significant advances were also made in the study of physical properties of frozen ground, particularly in the ratio of the solid phase to the liquid phase (ice ratio) and in the knowledge of geochemical processes that take place in the ground while it is in a frozen state. It has been shown, both theoretically and experimentally, that frozen ground is not in a state of "chemical rest," but that important changes take place in it at a subzero temperature. The study of patterned ground has advanced from surficial observations to a more thorough examination of ground and its structure beneath the surface, and an effort has been made to express mathematically the directions and magnitudes of the forces that produce patterned ground. Some difficulties, however, are still being experienced in arriving at a satisfactory mathematical formula to express the flow of heat in freezing and thawing ground. More intensive regional study of permafrost, especially in Russia, resulted in the accumulation of a vast amount of basic data that contribute to a better understanding of permafrost phenomena. A new maximum thickness of permafrost was established in arctic Siberia near Nordvik, where it was determined that permanently frozen ground attains a thickness of about 600 m or about 2,000 ft. In addition to other items, including improvements in technology to counteract destructive factors in permafrost areas, some revision and refinement have been proposed in the terminology employed in this relatively new science of Geocryology (cryo, a combining form from Greek: kryos - icy cold). To those who will be reading current Russian works on permafrost it should be pointed out that the old term Vechnaya merzlota (eternally frozen ground-permafrost) is now officially replaced by mnogoletnyaya merzlota (perennially frozen ground)—a change hardly warranted, for after all, what on this earth is actually "eternal" or "permanent"? The present book is based dominantly on published works by the Russian geocryologists: M.I. Sumgin, N.A. Tsytovich, N.I. Bykov, N.I. Tolstikhin, P.P. Shvetsov, B.N. Dostovalov, A.A. Grigor'yev, A.P. Bozhenova, S.P.Kachurin, I.A.Tyntyunov, and many others whose names appear in the selected bibliography at the end of the book. The text also includes the essential features of contributions by American and Canadian workers and embodies the author's own observations made from 1943 to 1945 and again in 1958.

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The author wishes to acknowledge the valuable assistance he has received from many of his colleagues here and abroad. He is especially indebted to Mr. W.H. Bradley of the U.S. Geological Survey, under whose administration he began the study of this problem. To Mr. H.G. Ferguson he owes his sincere gratitude for assistance in assembling the basic data and for many profitable suggestions and a critical reading of the 1943 manuscript. To Colonel Boyd Yaden he wishes to express his thanks for the opportunity to study permafrost phenomena in Alaska and Canada during the years 1943 to 1945. Colonel Yaden of the Air Transport Command made every effort to enable the author to reach any place with potential problems and placed at the author's disposal every facility of the Air Installation Office, of which he was in command. To Colonel Louis De Goes of the Air Force Cambridge Research Center and to Mr. Frank C. Whitmore of the U.S. Geological Survey he owes his thanks for the opportunity to revisit selected sites in Alaska in 1958. He also wishes to express his thanks to Dr. Troy L. Péwé for profitable discussion of certain aspects of the problem and for the use of photographs from his personal file. The author has derived much benefit from the friendly cooperation of Dr. R.F. Legget, Director of the Division of Building Research, National Research Council of Canada, and of his associates, who shared their knowledge of the Canadian permafrost problems. The author received valuable assistance from R.D. Daybell in the preparation of the chapter on physical and chemical properties of frozen ground, but he alone is responsible for the final presentation of the subject. To Alison Campbell thanks are due for her work in drafting illustrations. To various U.S. government agencies, he is indebted for permission to publish photographs illustrating permafrost phenomena. SIEMON MULLER

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T A B L E

O F

C O N T E N T S

List of Figures List of Tables

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PART 1 : INTRODUCTION

1

Definition of Permafrost History of Investigation Terminology

1 5 13

PART 2: PERMAFROST SCIENCE

Origin of Permafrost Geography of Permafrost Vertical Extent and Temperature of Permafrost Ground Ice Permafrost Landscapes Vegetation Physical Properties of Frozen Ground

PART 3: PERMAFROST AND ENGINEERING PROBLEMS

Logistics Investigation of Permafrost for Engineering Problems Excavation of Frozen Ground Drilling Methods in Frozen Ground Roads and Railroads Runways Bridges Dams and Reservoirs Mining Buildings Water Supply Utilities and Sanitation Materials Miscellaneous Engineering Problems

23

23 27 32 33 47 58 66

81

81 85 101 108 114 137 145 150 151 157 178 200 204 207

REFERENCES

209

APPENDIX 1. Select Bibliography APPENDIX 2. Glossary of Permafrost Terms APPENDIX 3. Key to Glossary sources

217 249 269

INDEX

273

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L I S T

O F

Figure 1. Figure 2.

Diagram of profiles with permafrost. Permafrost profile along a road through a swamp, Amur Province, Siberia (after Nikiforoff 1928). Temperature of the permafrost in the Shergin shaft, Yakutskm Siberia (after Middendorf, 1862). Flow of heat between air and ground in tundra country. Effect of snowfall in different seasons on the flow of heat between air and ground in tundra country. Distribution of permafrost in the Northern Hemisphere. Cross section through the Gorodskaya Protoka (channel of the Lena River) at Yakutsk showing extent of permafrost (after Svetozarov 1934). Permafrost map of Eurasia (from Sumgin 1940). Diagrammatic section through Siberia, from the Arctic Ocean to the Sea of Japan, showing relative thickness of permafrost and the active zone. Permafrost map of Eurasia (from Tumel' 1946). Permafrost map of Eurasia (from Baranov 1959). Ground ice occurrence: Lenses or intercalations, and veinlets, of ground ice near Whitehorse, Canada (courtesy of the U.S. Army Air Force). B. Lenses and wedges of ground ice exposed by hydraulicking in the placer mining operations near Fairbanks, Alaska (courtesy of the U.S. Geological Survey). C. Experimental freezing of sand (left) and clay (right) in an open system (approximately one half natural size): (A) Frozen cylinder, half sand, half clay. Much segregated ice in clay but not in sand. (B) Differential displacement of cylinder due to segregation of ice in clay but not in sand. Cavity caused by displacement of relatively dry sand (from Taber 1930). Diagrams showing nature of water migration in: (A) sand with initial moisture of 13 percent; (B) sand with initial moisture of 20 percent; (C) sandy clay with initial moisture of 39 percent. Diagram of ice-wedge exposures in an undercut bank of polygonal tundra (modified from Leffingwell 1919). (A) Diagram illustrating deformation of a cube of ground. (B) Stresses in the upper layer of frozen ground. (From Dostovalov, 1957). The stages of pingo growth: (A) early stage; there is the beginning of a bulge in poorly drained polygonal ground (photo by S. W. Muller); (B) "mature" pingo; the growth of the ice core ruptures the ground surface, exposing the ice. Melt of the ice produces trickles of mud along radiating cracks, giving the impression of a "mud volcano" (photo by S.W. Muller); (C) "mature" pingo (canoe in the foreground), Mackenzie Delta region, Canada (photo courtesy of J. Pihlainen); (D) pingo in the late stages of

Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. A.

Figure 13. Figure 14. Figure 15. Figure 16.

F I G U R E S

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the cycle, near complete disappearance (photo by S.W. Muller). Figure 17. Diagram illustrating formation of a frost blister. The mound is ruptured by hydrostatic pressure (and crystallization of ice?). Water freezes forming icing and ground ice. Occasionally, a hollow space is left in the core of a mound (after Nikiforoff 1928). Figure 18. Moisture profile of frozen ground indicating approximate level of permafrost table (After Guterman) Figure 19. Diagram showing ice ratio as percent of total moisture in different types of ground at various temperatures (after Tsytovich 1958). Figure 20. Examples of fluvial erosion in permafrost terrain: (A) erosion of small gullies is effectively retarded by snowbanks that remain until late spring or early summer and the ground beneath the snow remains frozen, resisting erosion (photo courtesy of F.C. Erickson); (B) melting of ground ice (ice wedges) at the intersection of polygons ultimately produces the "beads" in a beaded stream; (C) "beaded" stream, a typical landscape feature of permafrost terrain (photo courtesy of F. C. Erickson). Figure 21. Profile of asymmetric valley: (A) northern part of the Arctic; (B) southern part of the Arctic and Subarctic (after Presnyakov 1955). Figure 22. Examples of the types of patterned ground that occur in permafrost terrain: (A) Air photo of stone stripes, northern Alaska (photo courtesy of U.S. Navy). (B) Ice-wedge polygons with raised edges and with secondary smaller polygons within the larger ones, Arctic Canada (photo courtesy of J.A. Pihlainen). (C) Raised-center polygons develop where water, which normally stands stagnant in the trenches, finds an outlet through a more or less well established drainage system. As more water is drained off from thawing ice wedges, the raised edges of the polygons gradually slough-off into the troughs (photo by S.W. Muller). (D) Air photo of large-scale ice-wedge polygons, Colville River delta, northern Alaska (photo courtesy of U.S. Navy). (E) Oblique air view of solifluction lobes or festoon terraces, Brooks Range, Alaska (photo by S. W. Muller). (F) The pattern of ice-wedge polygons is accentuated by different kinds of vegetation and by standing water in some of the depressed-center polygons (photo by S. W. Muller) (G) Stone rings (photo courtesy of T. L. Péwé). Figure 23. Cave-in lakes, near Northway, Alaska: (A) in winter; (B) in process of formation; (C) near end of the thaw-lake cycle (photos by S. W. Muller). Figure 24. Air photo showing beaded stream and oriented thaw lakes along the Arctic Coastal Plain, northern Alaska (photo courtesy of U.S. Navy). Figure 25. Thermokarst features: (A) a sinkhole produced by melt of ground ice; (B) residual mounds produced by the melt of ice wedges. Both photos are from near Fairbanks, Alaska (both photos courtesy of T. L. Péwé). Figure 26. The combined effect of moss, peat, and snow on the distribution of roots and summer ground temperatures in I: forest, II: forest-tundra, and III: tundra, at latitudes 65°N, 68°N, and 70° N. (after Govorukhin 1957). XXXll

Figure 27. Distribution of permafrost in relation to relief and vegetation in southern Transbaykalia (after Tolstikhin 1941). Figure 28. Swelling of ground on freezing from the top (after Vologdina 1936). Figure 29. Supercooling of water in ground of different texture (after Bozhenova 1955) Figure 30. Diagram illustrating heat conductivity of clay, sand, and water at different temperatures (after Evdokimov-Rokotovsky 1932). Figure 31. Diagram illustrating how annual ground temperature isotherms are affected by the shadow of an east-west fence. Figure 32. Work feasibility chart and climatic constraints, Point Barrow, Alaska (1) (modified after P. W. Roberts) Figure 33. Work feasibility chart and logistical constraints, Point Barrow, Alaska (2) (modified after P. W. Roberts). Figure 34. Diagram showing the compressive strength of frozen ground at different temperatures (from Tsytovich 1945). Figure 35. Sketches to illustrate measurement of ground temperatures during excavation. Figure 36. Testing of different materials and the design of apparatus to measure ground temperatures at the Fairbanks Permafrost Research Site (photo by S. W. Muller). Figure 37. Benchmark of standard design dislodged by frost heave (photo courtesy of T.L. Péwé). Figure 38. Diagram illustrating the setting of a benchmark. A metal pipe perforated near the base is embedded in pre-thawed or augered ground to a depth three times (3h) the thickness of the active zone (h) (from Bykov and Kapterev 1940). Figure 39. Testing of different designs of benchmarks at the Fairbanks Permafrost Research Site (photo by S.W. Muller). Figure 40. Design of a "swellometer" (after Bykov and Kapterev 1940). Figure 41. Hydrological problems: (A) a caisson constructed for a cesspool is flooded with water and mud from thawed permafrost and groundwater from táliks (photo by S. W. Muller); (B) small craters were formed by "siphoned" seepage of water into a borrow pit during the spring flood of the Yukon River (photo courtesy of T.L. Péwé). Figure 42. Use of ripping passes by caterpillar tractor. In the ripping process, the tractor first makes a pass with very slight penetration to loosen the surface. With resulting better traction, it then makes a series of passes, lowering the tooth deeper each time, until maximum penetration is reached (diagram courtesy of Caterpillaer Tractor Co.) Figure 43. At one of the Mesabi mines, there was a saving of 88.8 percent on overburden loosening costs by ripping of 4-ft. centers. Several passes were made in the direction of the upper right corner of the diagram. A final pass was made at right angles to the first to take advantage of weak points in the material. Cross-ripping produced the most effectively loosened material of all (diagram courtesy of Caterpillar Tractor Co.). XXXlll

Figure 44. Excavating frozen ground using ripper techniques: (A) photo showing the 8-ft. ripper teeth reaching maximum penetration of about 4 ft. during ripping of frozen clay at Mesabi mine. Used as a substitute for drilling and blasting, the ripper was able to loosen frozen ground for shovel loading for between 10 percent to 40 percent of comparable shooting costs. (B) When subject to ripping, the frozen overburden breaks off in large unwieldy slabs as power shovels attempt to loosen untouched material. Such large pieces are extremely difficult for power shovels to handle and result in additional maintenance for shovels used to break overburden (both photos courtesy of Caterpillar Tractor Co.). Figure 45. Road maintenance: (A) sanding of icy roads on a grade. Note the high banks of snow along the shoulders; (B) snow scraped off the road onto the shoulders retards thaw of the shoulders in spring, obstructing normal subdrainage beneath the roadbed and producing impassable quagmires (both photos courtesy of the Bureau of Public Roads). Figure 46. Road construction (1): (A) Wrong construction method; (B) right construction method. Figure 47. Road construction (2): (A) Shallow rooted trees are easily felled by bulldozer in clearing ground for road construction. The turf and top soil are also scraped, thereby exposing and allowing underlying permafrost to thaw. (B) Denuded of the insulating vegetative blanket, the melt of ground ice turns the road into an impassable quagmire (both photos courtesy of Bureau of Public Roads). Figure 48. Road construction (3): (A) Vegetation on the path of a road is cut (not bulldozed) and spread over the ground to insulate and thus prevent the thaw of underlying permafrost. (B) Vehicular traffic at this stage of construction should be kept to a minimum (both photos courtesy of Bureau of Public Roads). Figure 49. Road construction (4): (A) Non-frost-active basecourse aggregate (gravel) is dumped on the vegetative blanket; (B) Additional fill on shoulders insures better stability of the road. More fill should be placed on the shoulder than is shown in the picture and the material (berm) should be graded to facilitate proper functioning of snow-removing equipment (both photos courtesy of Bureau of Public Roads). Figure 50. Thermal effects of roads: (A) The effect of road fill on permafrost table; (B) Diagram of ground isotherms in road fill in September shows deeper thaw on the south side than on the north side (from Sumgin 1940). Figure 51. Diagrams to illustrate varying hydrologie regime of terrain when traversed by a newly constructed road: (A) Sloping terrain prior to construction; (B) Thawing of permafrost under shoulders causes sloughing of road bed; permafrost bulge beneath road bed blocks subsurface drainage and causes icing in late winter; (C) Permafrost rises under berm; road bed remains stable; subsurface drainage intercepted and carried away in ditch. Figure 52. Two views (A, B) showing an extended spillway from a culvert on the Alaska Highway that was constructed in order to prevent road shoulders xxxiv

from accelerated erosion and damage (both photos by S. W. Muller). Figure 53. Diagrams showing: (A) lag of minimum and maximum ground temperatures at the base of the active zone at Skovorodino, Siberia; (B) lag of ground temperatures behind air temperatures (after Tsytovich and Sumgin 1937). Figure 54. Icings: (A) an icing on the Alaska Highway; B the "frost belt" in action. The icing is induced across the water course uphill from highway (3) (Both photos courtesy of Bureau of Public Roads). Figure 55. Diagram illustrating the elimination of icings by the "frost-belt" method: In cross-section "X" the freezing of ground down to the permafrost prevents water from percolating through the partly frozen active zone (down to level "b") causing icing at "A". In cross-section "Y", while undisturbed ground freezes down to level "c", the ground in the "belt" freezes down to permafrost while inducing an icing at "A", some distance uphill from the road (after Petrov 1930). Figure 56. Diagram showing the extent of the icing that occurs on the Amur-Yakutsk Highway at the Onon River crossing, Siberia. The plan also shows the projected frost belt. In the upper left, the flooded area with ice blocks (indicated by the wavy lines) is the result of the explosion of an icing mound. Figure 57. Diagram illustrating a variant of the frost-belt method proposed by Bykov and Kaspterev (from Bykov and Kapterev 1940). Figure 58. Winter maintenance of roads (1): (A) A culvert plugged with ice is being thawed by an oil-burning flame thrower (photo courtesy of Bureau of Public Roads); (B) A steam jet is used to open an ice-plugged culvert (photo courtesy of the Signals Corps, U.S. Army). Figure 59. Winter maintenance of roads (2): Drums with burning oil facilitate drainage through the culvert (courtesy of the Signals Corps, U.S. Army). Figure 60. Photograph showing "mud jacking" on a runway that settled because of the melt of ground ice in underlying permafrost (photo courtesy of U. S. Air Force). Figure 61. Diagrams to show the effects of snow piled on the shoulders of a runway: (A) early winter, (B) late winter. Figure 62. Photo showing how surface drainage from a runway can be affected by an extended gutter that prevents erosion of the shoulders (photo courtesy of T. L. Péwé). Figure 63. Diagram to show the relationship between the flying weight of an aircraft and the required thickness of freshwater ice that forms the airstrip. Figure 64. Typical profile of the permafrost table near a large river in Siberia (after Datsky 1937). Figure 65. Bridge construction in permafrost terrain (1): (A) Bridge damaged by frost heaving of the piles, Central Alaska; (B) close-up of the damaged bridge (both photos courtesy of T. L. Péwé). Figure 66. Piles driven during the construction of the Nisutlin Bridge, Alaska, have xxxv

Figure 67.

Figure 68.

Figure 69. Figure 70. Figure 71. Figure 72. Figure 73. Figure 74. Figure 75.

Figure 76.

Figure 77.

the butt end pointing upwards instead of the recommended practice of driving piles butt end downwards to ensure better "anchoring" and resistance to frost heaving (photo courtesy of Bureau of Public Roads). Bridge construction in permafrost terrain (3): (A) Railroad trestle over a small gully shows the effect of frost heaving; (B) Side view of the same trestle showing the abandoned piles that were shortened during the winter frost heaving to maintain the grade of the track. The piles settle when the ground thaws during summer (both photos courtesy of T. L. Péwé). Bridge construction in permafrost terrain (4): (A) A trestle bridge with short horizontal spans is more likely to be damaged by slabs of ice and other floating debris than a bridge constructed with long horizontal spans; (B) Damage to the Tok River Bridge, Alaska, washed out at one approach, because improper design obstructed flow of water laden with debris beneath the bridge. The backed-up water forced its way through the soft approach fill (both photos courtesy of Bureau of Public Roads). Diagram showing how frozen ground thaws with different steam and water conditions (after Janin 1922). Diagram showing thaw of frozen gravel using the Miles Method, in which the water is at natural temperatures. The less permeable layer thaws more slowly. Sketch of a thaw point. The thaw of frozen gold-bearing gravels: (A) using cold ditch water; (B) after the thaw points have been driven to the desired depth (both photos courtesy of U.S. Army Air Force). Diagram to show the effect of (A) an uninhabited (that is, non-heated) and (B) an inhabited (that is, heated) house on the permafrost table (from Tsytovich and Sumgin 1937) Ground isotherms under an experimental house in Transbaykaliya, Siberia (from Tsytovich and Sumgin 1937). Effects of a heated building upon permafrost at Northway, Alaska: (A) Insufficient insulation beneath the concrete floor slab caused melt of ground ice in underlying permafrost and settling of the floor. Placement of steam pipes at floor level accelerated the thaw of underlying permafrost, (photo by S.W. Muller); (B) Hot water in the shower room caused rapid melt of ground ice and the settling and breakage of the concrete floor slab (photo courtesy of U.S. Army Air Force). Diagram illustrating thaw of permafrost beneath a building: (A) shows the maximum permissible lowering of the permafrost table beneath the foundation; (B) illustrates how insufficient insulation or excessive heat transfer causes ground thawing. If the thawed ground has low bearing strength the building settles and suffers damage (after Bykov and Kapterev 1937). "Mud jacking" of a floor inside a building at Northway, Alaska. Holes are drilled in the concrete floor slab and a mud-cement mixture is driven xxxvi

Figure 78. Figure 79. Figure 80. Figure 81.

Figure 82.

Figure 83.

Figure 84.

Figure 85.

Figure 86. Figure 87.

beneath the floor under high pressure to lift the floor to its original position (photo by S.W. Muller). The suggested design of ceilings and floors for living quarters in permafrost areas. The suggested design of a foundation for a steel tower in permafrost areas. This building, near Fairbanks, Alaska, is almost completely engulfed in an icing that originated upslope from the shack (photo courtesy of U.S. Army Air Force). Icings can be caused by buildings: (A) diagram to illustrate how the escape of water from the unfrozen active zone occurs through the interior of an inhabited house; (B) an icing that originated beneath this heated, now abandoned, building has completely filled the building interior and spilled into the yard through a window (photo from Tyrrell 1904). An overturned barrel left standing in the yard started an icing which filled the lower half of the barrel and spilled through the plug-hole in the middle. This icing spread over the greater part of the yard and flooded some building (from A. V. L'vov 1916). Piles in permafrost (1): This photograph illustrates faulty driving of piles for a building. The water-filled crater around the left pile indicates that the ground was pre-thawed by the steam jet in excess of need; the ground around this pile may not freeze back in time to anchor it in the permafrost and the pile may heave during the coming winter. The ground around the right pile was not sufficiently pre-thawed and, as a result, the pile was not driven to its proper depth; the mashed top of the pile is evidence of the resistance to penetration (photo by S.W. Muller). Piles in permafrost (2): (A) Piles pointed at the butt end are greased and wrapped in tar paper to reduce adfreezing and frost heaving during freezing of the active zone; (B) After this pile was anchored in permafrost, frost heaving in the active zone lifted the tar paper wrapping the pile (both photos by S.W. Muller). Buildings at the Fairbanks Permafrost Research Site, Alaska: (A) Adequate subfloor ventilation protects the underlying permafrost from thawing and damaging this experimental house; (B) An experimental garage is built on a fill of gravel with adequate subfloor ventilation; (C) An experimental garage that failed (settled) because of inadequate subfloor ventilation that allowed heat from the building to melt the ground ice in the underlying permafrost (photos: A and B by S.W. Muller; photo C courtesy of T.L. Péwé). A sequence of photographs (A-D) showing the manual operation required to procure a water supply from a lake near Point Barrow, Alaska. The mechanized procurement of water supply from a lake is achieved by a water tank on sleds installed inside a heated enclosure (wanigan) and pulled by a D-8 tractor (photo courtesy of D. Knudsen, Barrow, Alaska). xxxvii

Figure 88. Diagram showing the occurrence of ground water in permafrost regions. Figure 89. Diagrams showing the laying of water pipes in permafrost areas (From Tsytovich 1959). Figure 90. A pump house, Alaska: (A) External view; diagonal wrinkles on the roofing paper indicate torsion during uneven settling of the building; (B) In the interior, the water-well casing on the left has separated from the concrete pedestal and the floor slab, placed directly upon permafrost without adequate insulation, has settled several inches. This damage was due to excessive heat in the building causing underlying ground ice in the permafrost to melt (both photos by S.W. Muller). Figure 91. Water storage tank at Norway, Alaska: (A) General view; (B) Close-up of the support design of the water tank (photos by S.W. Muller). Figure 92. Utility lines, enclosed in utilidors to prevent freezing of steam and hotwater pipes (photo by S.W. Muller). Figure 93. Diagram showing ground isotherms (Celsius) near to a water pipe before the flow of water (left hand side) and during the flow of water (right hand side). Figure 94. Nomogram for determining temperature in water pipelines. Figure 95. Photo showing wiring pulled from a switch by the settling of the floor slab (photo by S.W. Muller). Figure 96. Utility poles in permafrost: (A) the destructive effect of frost heaving on utility poles may be delayed but not entirely eliminated by bolting a cross-beam at the base of the pole. This photo shows the effect of one winter's heave; (B) The problem of "uprooting" of utility poles is solved through the use of tripods (both photos by S.W. Muller). Figure 97. Photo shows gas pipeline lying on the ground surface. This makes maintenance and repair easy (photo courtesy of the Signals Corps, U.S. Army). Figure 98. Graph showing curing time of concrete under cold-weather conditions (supplied by O.W. Walvoord). Editors' Note: There were 144 figures in the original manuscript. Some of these figures have been amalgamated. One figure in the manuscript (Figure 27, entitled 'Moisture profile of frozen ground') was not cited but is now in the text as Figure 18.

xxxvni

L I S T

O F

Table l.

Liquid and sold phases of water in frozen quartz sand of different textures (after Nersesova and Tyutnov 1957). Effect of pressure on the amount of water in liquid phase in frozen ground (from Tsytovich 1957). Supercooling of water in relation to intensity of cooling (from Bozhenova 1957). Effect of moisture content and pressure on the temperature of the beginning of freezing of ground (from Bozhenova 1957). Compressive strength of frozen ground at temperatures from -0.3°C to -2.0°C (from Tsytovich and Sumgin 1937). Elastic and plastic deformation of frozen ground under compression (from Tsytovich and Sumgin 1937). Shearing strength of ice-saturated frozen ground (from Tsytovich and Sumgin 1937). Effect of temperature on the shearing strength of frozen ground (from Tsytovich and Sumgin 1937). Scope and plan of field investigation of permafrost. Effect of temperature on tangential adfreezing strength of different materials (from Tsytovich and Sumgin 1937). Effect of temperature and moisture content on the tangential adfreezing strength between different ground and water-saturated wood and concrete (from Tsytovich and Sumgin 1937). Tangential adfreezing strength between different frozen ground and water-saturated wood (from Tsytovich and Sumgin 1937). Values of permissible stresses on ice-saturated ground (from Tsytovich and Sumgin 1937). Calculated values of tangential adfreezing strength in kg/cm2 (from Tsytovich and Sumgin 1937). Classification of groundwaters in the permafrost province. Values of coefficient K1 and K2 cal/m2 per hour per °C during the normal operation of the distribution system.

Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16.

T A B L E S

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P A R. T

l

Introduction Definition of Permafrost PERMAFROST (OR PERMANENTLY FROZEN GROUND) is defined as a thermal condition of soil or other surficial material, or even bedrock, in which the ground exists at a temperature below 0°C (32°F) continuously for a number of years (two to thousands). Permafrost may exist in unconsolidated soil, in gravel, or even in bedrock. Generally, permafrost results in the occurrence of the solid phase of water (ice), either as interstitial cementing particles or as more or less large monolithic bodies of ice—ground ice. There are, however, cases where ground, at temperature below 0°C (32° F), may contain little or no moisture (ice). This condition is referred to as dry permafrost. Dry frozen conditions are usually found in sandy or in other coarse-grained, clastic materials that drain easily. From the standpoint of construction engineering, the properties of dry frozen ground are similar to those of unfrozen ground. In grading or excavating operations, dry frozen ground has neither the hardness nor induration that characterizes permanently frozen ground containing moisture in the form of ice. Nonetheless, in some engineering projects, such as sewage disposal and other pipeline construction, dry frozen ground with temperatures below 0°C (32° F) cannot be ignored despite the ease of excavation, as pipes placed in such ground may freeze and become damaged. N.I. Bykov and P.N. Kapterev (1938) distinguish between permanently frozen ground and merely frozen ground. According to the generally accepted definition, permanently frozen ground may contain little or no water but frozen ground always implies the presence of water in the form of ice. It should be noted in this connection that not all ground that contains water and whose temperature is below 0°C (32° F) is necessarily frozen ground, because there are conditions under which water does not turn into ice even at temperatures considerably below 0°C (32°F). Water with appreciable amounts of dissolved salts may be encountered circulating in the ground, the temperature of which may be well below the 0° C (32°F). For example in 1885, Ray reported a fluid brine seeping into the shaft at Point Barrow where the temperature was about -10°C. The ground above permafrost is subject to alternate freezing during winter and thawing during summer. This veneer of surficial ground, varying in thickness from several centimeters to several meters, is called the ACTIVE ZONE (Figure 1). It 1

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 1. Diagram of Profiles with Permafrost

represents the zone in which perceptible and often destructive physico-chemical processes take place annually. These processes generally manifest themselves on the surface by visible and measurable changes or activity (heaving, settling, cracking, and such). Hence, the adjective "active" in the term Active Zone appears to be appropriate. The term "active zone" is preferred to active layer for the reason that it is more likely to avoid ambiguity and confusion if need should arise to refer to various ground layers within the zone. It is also a fact that the active zone may cut diagonally across the layered structure of the ground surface.

2

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Commonly, the behavior of seasonally frozen ground is quite different in areas where it is directly underlain by permafrost from that where the permafrost table may be at some depth or where there may be no permafrost at all. A need for precise definition of the active zone (active layer) was voiced by M.I. Sumgin as far back as 1937. Before arriving at the final formulation of this concept, it is necessary to make a clear distinction between the various components or elements that were previously embodied in the concept of active zone or "active layer." It has been suggested that ground that thaws out during the summer—seasonally thawed ground—be distinguished from seasonally frozen ground. The condition of ground and its surface features is quite distinct during these two different thermodynamic states. P.P. Shvetsov (1956b) suggests that the "active layer" of M.I. Sumgin should be termed the "seasonally thawed layer." In reality, this represents a temporarily thawed state of the ground. During the winter this ground freezes down to the permafrost and forms with permafrost a monolithic system. In seasonally thawed ground, the exchange of heat is predominantly within the range of temperatures below 0°C (32°F), whereas in seasonally freezing ground, the exchange of heat generally ranges within the limits of positive temperatures, with the average temperature controlled by the variety of local environmental conditions. The commission on terminology of the Institut Merzlotovedeniya, Academy of Sciences of the USSR (P.P. Shvetsov 1956b), suggests that the term active layer be abandoned and replaced by the term "seasonally thawed layer." Realizing that it is desirable to distinguish seasonally frozen ground from seasonally thawed ground, it is nevertheless felt that the term active layer, here referred to as active zone, should be retained to designate the thickness of ground that freezes in the winter and thaws in the summer. Lest there be ambiguity about the scope of the concept of an active zone, this term will be used in this report to include that thickness beneath the ground surface that freezes in winter and thaws in summer, irrespective of its relationship to permafrost. Thus, the active zone may extend either downwards to merge with permafrost or be separated from permafrost by a greater or lesser thickness of unfrozen ground (tálik). The thickness of the active zone is variable. As a rule it is fairly thin in the north and becomes thicker to the south. Its thickness depends on the composition of the ground, hydrology, vegetation, snow cover, air temperature, and other climatic factors. For example, on a river terrace composed of water-saturated sandy clay covered by 0.5 m of peat and moss and having a sparse stand of larch, the thickness of the active zone may be 0.5 to 0.8 m. However, under essentially the same conditions, except that instead of larch the vegetation consists of grasses and stands of broad-leaf trees such as birch, alder, and poplar, the thickness of the active zone may be 1.5 to 2.5 m. Finally, in the same valley, on the next higher terrace, which might be composed of well drained sandy material with a vegetation cover consisting of lichens, dry mosses, and tall pines, the thickness of the active zone may be between 2.5 and 3.5 m. Similar relations hold true for the more northerly areas in the permafrost region, although actual thickness may be somewhat smaller. In the polar region, in different types of ground and in different surroundings, the average thickness of the active zone may be as follows: 3

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Ground type Areas south of the 55th parallel At about the 62nd parallel Along the coast of Arctic Ocean

Sandy Ground (m) 3. Oto 4.0

Clayey Ground (m) 1.8 to 2.5

Ground with Peat and Swamps (m) 0.7 to 1.0

2.0 to 2.5 1.2 to 1.6

1.5 to 2.0 0.7 to 1.0

-0.5 0.2 to 0.4

Owing to the fact that environmental conditions vary considerably within short distances, the bottom of thawed ground is a rather uneven surface. By analogy with groundwater terminology, this surface will be called the frost table. With the downward progress of seasonal thaw, the frost table moves progressively lower until it either disappears when it reaches underlying unfrozen ground or merges with the upper surface of the permafrost. The surface that represents the upper boundary of permafrost is called the permafrost table (see Figure 1). It does not necessarily coincide with the frost table. Like the frost table, however, its irregularities are determined by the insulating cover of vegetation, by differences in heat conductivity of the ground, by the geographic position and the character of exposure, and by the hydrology of the ground. For example, in the sketch reproduced from C.C. Nikiforoff (1928) (Figure 2) the permafrost table is higher where the ground is insulated by a cover of peat and moss and is slightly depressed where the ground is bare. Locally, especially near the fringe area of the permafrost region, the permafrost table lies at a depth that is greater than the level reached by winter freezing. As a result, a layer of unfrozen ground occurs between the frozen active zone above and the permafrost below. This layer of unfrozen ground is designated by the Russian term tálik, meaning thawed ground. The term tálik is also applied to layers or lenses of unfrozen ground that may occur within permafrost and to unfrozen ground that lies beneath permafrost. Permafrost with intercalations of táliks is referred to as layered or interrupted permafrost. Individual táliks in layered permafrost commonly serve as aquifers, and their water is, as a rule, under considerable hydrostatic pressure. Táliks, therefore, may be useful as a source of water supply and also as suitable beds in which to lay water pipes because the pipes imbedded in a tálik are not likely to freeze and break. Occasionally, some táliks, particularly those composed of silty material, behave as more or less viscous liquids. They flow like molasses and are comparable to mud-flows, but they may occur within a wide range of depths below the surface and are not restricted to the superficial material. This fluid, muddy material is designated by the term slud, a provincial English word for soft, wet mud or mire. The corresponding Russian term isplyvun, which means that which flows. Where permafrost is relatively thin and the overlying active zone consists of porous material, relatively warm surface water may percolate freely through this porous ground and thaw its way clear through the underlying permafrost. Such "islands" of unfrozen ground, completely surrounded by permafrost, are also called

4

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 2. Permafrost profile along a road through a swamp, Amur Province, Siberia (after Nikiforoff 1928). táliks. It is likely that some of these islands of tálik have formed where permafrost was either dry or only partly saturated with ice, thus permitting the free percolation of relatively warm surface water. Islands of tálik become progressively more common toward the southern boundary of the permafrost region. The lower limit, or base, of the active zone differs in position slightly from year to year. Occasionally, owing to excessive winter cold or to subnormal summer temperatures, the summer thaw stops short of the usual level, leaving a layer of frozen ground between the thawed part of the active zone and the tálik. This isolated frozen layer, lasting only one or two seasons, is designated by the Russian term pereletok, meaning that which survived during the summer (see Figure 1). The combined thickness of ground above permafrost, consisting of the active zone and tálik, and, wherever present, pereletok, is referred to as the suprapermafrost zone. The thickness of the supra-permafrost zone depends chiefly on hydrothermal conditions at the site and, to a lesser extent, on latitude. Near the southern limit of the permafrost region, this layer is generally thicker than the active zone. This relationship may also exist locally farther north, especially along the slopes of mountains and near large rivers and lakes. But in the greater part of the permafrost region the suprapermafrost zone coincides with the active zone. The study of permafrost with all its aspects (origin, behavior, distribution, composition, structure, and such) is a part of a broader science termed GEOCRYOLOGY. This science also concerns itself with the effect of human activities upon the natural state of ground and considers the measures taken by man to control the thermodynamic factors of the ground during freezing, thawing, and while in the frozen state. As with other natural history sciences, geocryology overlaps with, and depends upon, disciplines from related sciences such as geology, mineralogy, pedology, hydrology, chemistry, physics, geography, biology, and climatology.

History of Investigation Probably the earliest published record of the existence of permafrost is contained in the account of Martin Frobisher's voyage to Baffinland in 1577. Frobisher observed

5

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS that "four or five fathoms within the ground, for lack of the said moisture /flowing streams/, the earth (even in the very summer time) is frozen, and so combineth the stones together, that scarcely instruments with great force can unknit them." In 1773 and again in 1775 Ivan Lyakhov journeyed to the New Siberian Islands where he observed that the islands were composed of ice and sand. Along the shores, eroding from thawing by the sun, tusks and bones of mammoths were found in great abundance. In the latter part of the 18th century, Johann Gmelin made known the existence of permafrost at Yakutsk and in the Transbaikal region. At approximately the same time, Peter Simon Pallas published on the discovery of a rhinoceros carcass, and Gavrila Andreevich Sarychev reported on a mammoth. Scientific interest in permafrost was further aroused in 1797 by the discovery of a frozen mammoth on the Bykovskiy Peninsula just east of the mouth of the Lena River. A special expedition was organized by the Russian Academy of Sciences, and the animal was extracted and shipped to Petersburg. The specimen is now on exhibit in the Zoological Museum in Leningrad. It actually consists of two exhibits. The stuffed skin with fur is placed in the exact position in which it was found in the field while the skeletal bones are assembled in normal upright position. Perhaps the most significant single event early in the 19th century, which attracted among scientists a widespread interest in permafrost, was the unsuccessful attempt by a merchant, Fedor Shergin, to dig a well for water at Yakutsk, central Siberia. The German naturalist, Georg Erman, in an account of his journey around the world in 1828-30 (Reise um die Erde durch Nordasien and die hieden Ozeane, 1848, v. 2, p. 367), gives the following account of his visit to Shergin's well on April 13, 1828: The work [on the well] was begun at the beginning of last summer, and continued without interruption to a depth of forty-two feet. But at that time, the warmest part of the y ear, the strata of fine sand and clay which formed the sides of the shaft were found to be uniformly frozen hard, so that, instead of digging with the spade, it was necessary to have recourse to a miner s pick axe. The flakes and frozen pieces of earth in the interior of the well seemed perfectly dry, and they had to be carried up into the warm air and thawed before they gave any signs of moisture. They had now been working again at the well for some days, and an excellent opportunity was thus presented to determine the temperature of the ground for Yakutsk. For this purpose, I paid M. Shergin a visit on the 13th of April, and descended into the well by means of the windlass erected over it. The workmen employed in it had added two feet to the depth of the shaft that very morning, and about six feet during the immediately preceding days, so that the bottom just broken up was fifty feet below the surface, and six feet under the timber framing of the shaft which ended with the work of the preceding summer. I there buried the bulb of a thermometer at different places in the ground at the bottom, but never saw the mercury in it rise above -6°R /= -7.5°C/. Consequently it is a decided winter temperature which prevails here in the ground at

6

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS a depth where no change takes place, and even supposing that the increase of heat, from the surface to the centre of the earth, is as rapid here as in other places, yet even so we could not expect to find water in the fluid state till we arrive at the depth of 630 feet; for to that depth the ground is frozen. The news of the presence of permanently frozen ground in the interior of Siberia was received with skepticism by some scientists. Leopold von Buch, an eminent naturalist, refused to believe that ground that supports trees, bushes, and flowers year in and year out can remain frozen. Again, the Russian Academy of Sciences organized an expedition to investigate this phenomenon under the leadership of Alexander von Middendorf, who was especially instructed to investigate the Shergin well. Middendorf carried out the Academy's assignment to a high degree of success. He measured ground temperatures in the Shergin shaft and at other places in Siberia and devoted much time and effort to the study of permafrost in Siberia from the Yenisey River to the coast of the Sea of Okhotsk. By extrapolating the thermal gradient, Middendorf came to the conclusion that the frozen ground at Yakutsk is probably in the order of 230 m in thickness (Figure 3). All doubts about the existence of permafrost were dispelled in the minds of western scientists by Middendorf's report, as has been acknowledged by Humboldt in his publication Cosmos. During the ensuing several decades, the study of permafrost bore, for the most part, the character of incidental observations in connection with other studies and projects. These observations, however, furnished much valuable factual information on the geographic distribution of permafrost, on its thickness, and on certain correlations between permafrost and the various factors of environment. There were many individuals connected with the institutions of higher learning and with private research organizations who were making a significant contribution to the knowledge of permafrost before 1900 (e.g. Russell 1890) The construction of the Trans-Siberian Railroad at the turn of the 20th century brought Russian engineers face-to-face with the formidable difficulties of permafrost along the proposed railway route. Similar difficulties were encountered later in the construction of the Amur railroad, which runs parallel to the course ofthat river but some distance away from the river itself. The unexpected failure of water supply during the winter necessitated construction of access branches to the river for the sole purpose of water procurement. The problems encountered in the search for water supply during the construction of the Amur railroad are discussed in great detail by A.V. L'vov (1916), whose book remains a classic on some phases of hydrology in the permafrost region. The seriousness of the problem and its significance in the national economy of Asiatic Russia was already realized before the 1917 revolution, and several experimental stations were established in Central Siberia to carry out research on frozen ground phenomena. Perhaps the greatest single impetus to the study of permafrost in Russia was the publication by M.I. Sumgin of Permafrost within the limits of the USSR (Sumgin 1927). This work may well be regarded as the starting point of geocryology as a distinct scientific discipline. In his book, Sumgin assembled all that had been previously known on the subject, critically analyzed the factual data, 7

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 3. Temperature of the permafrost in the Shergin shaft, Yakutskm Siberia (after Middendorf, 1862).

8

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS formulated basic concepts, and suggested lines for future studies. As can be seen from the map of areal distribution of permafrost in the USSR prepared by Sumgin, dominant consideration was given to climatic factors. Thus, the different "provinces" of permafrost were based primarily on temperature measurements with relatively little regard for the composition, structure, and hydrological nature of the ground. During the 1930s, the accelerated colonization and industrial development of Siberia was accompanied by an increased tempo in the study of permafrost. In 1930, at the initiative of Academician V.I. Vernadskiy and of M.I. Sumgin, the Academy of Sciences organized a Commission for the study of permafrost, Komissiyapo izucheniyu vechnoy merzloty. In 1936, the Commission was reorganized into a Komitet po vechnoy merzlote (a committee), and in 1939 into Institut Merzlotovedeniya (Institute of Geocryology). During the following decades, the commission, the committee, and the institute successfully functioned as centers of organized scientific investigation into frozen ground. Among the notable accomplishments of these organizations were numerous large-scale expeditions, particularly those in connection with the construction of the Baikal-Amur Railroad, and expeditions to the Vorkuta region, and the mining district of Noril'sk. By 1941, marked advances had been made in the understanding of permafrost phenomena, as witnessed by important publications on the general subject by M.I. Sumgin (1931; 1934; 1940; Sumgin and Demchinskiy 1940), on engineering problems by N.A. Tsytovich (1930), and on hydrology by N.I. Tolstikhin (1936; 1941 ). However, in spite of the accumulation of factual data, theoretical generalization and the formulation of basic principles lagged considerably behind the demands of practical problems that were the result of the accelerating industrial and economic development of the Arctic. As can be judged from the account of the 7th Interdepartmental Conference on Permafrost in the USSR, held in 1956, there are today almost 100 different industrial organizations and academic institutions that participate in some phase of permafrost investigation. It is reasonable to assume that, today several hundred properly trained and qualified scientists take part in this study. The University of Moscow has a chair of Merzlotovedeniya (Geocryology), where men and women are being trained for work in Arctic regions. Some training of future scientists in permafrost is also done at the Institut Merzlotovedeniya of the USSR Academy of Sciences and at the Arctic Institute in Leningrad. The expanded activity in the study of permafrost in the USSR has resulted in the appearance of a large number of publications dealing with the various aspects of this subject. The certain amount of economic autonomy of the various government agencies in the USSR has inadvertently brought about some overlap of activities and has resulted in a compelling demand for better coordination between the different institutions. The trend appears to be to center all theoretical research in the Institut Merzlotovedeniya (Geocryology) with all its branches. Applied research is being carried out by the Institute at its various experimental stations, (Vorkuta, Igarka, Yakutsk, Skovorodino, and others). Russian geocryologists have felt that there is a need for a commission to review and to formulate precise definitions of scientific concepts in the field of permafrost studies. It was also urged that annual symposia on special topics be organized and that a conference on permafrost between 9

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS the different organizations be held at least once every five years. The rapidly growing volume of scientific literature in this relatively new scientific discipline brought forth a need for a review and precise formulation of definitions of concepts and terms. Accordingly, an inter-departmental commission on permafrost was established in the USSR in 1950 and, in 1956, after several years of deliberation, the Institute of Merzlotovedeniya published a provisional list of terms and their definitions. In this pamphlet, dealing with basic concepts and terminology, the long-used term vechnaya merzlota (permanently frozen ground) is replaced by the term mnogoletnyaya mierzlota (perennially frozen ground). Other new terms and their definitions are discussed below in Section 1.3 (Terminology). Disapproval of some of these new terms, including the mnogoletnyaya merzlota (perennially frozen ground), has been recently voiced by A.V. Stotsenko and A.M. Chekotillo (1962) Relatively little work on permafrost has been done in Western Europe, most of which lies outside the area of permanently frozen ground. There is, however, a noticeable increase in interest and active participation on the part of members of the Arctic Institute of Denmark and the Scott Polar Research Institute in England. The Scott Polar Research Institute was established in Cambridge, England in 1926. It serves as a center of information on polar regions. The institute maintains a library of books, manuscripts, and maps, and every four months publishes the Polar Record, which contains reviews of expeditions, news items, and lists of new articles and books dealing with the polar regions. The facilities of the Institute are offered freely to scholars of all nations interested in polar problems. An impressive work was published in Germany by C. Troll (1944; English translation 1958) on solifluction and patterned ground. The terminology introduced in this work is overwhelming. Much of it is new and perhaps somewhat premature because various types of patterned ground are not yet fully understood from the viewpoint of their origin and structure. Troll's paper is based on first-hand observations and draws freely on previously published sources. It has a long list of bibliographic references, including many titles in Russian. A comprehensive study of frozen ground and ground ice was made by A.E. Leffingwell (1919), covering the area of Canning River, Alaska. Leffingwell described the formation of ice wedges and other types of ground ice, in which connection he gave the views of earlier workers including those who studied this subject in Siberia. A significant contribution was made to the understanding of permafrost by S. Taber (1918; 1930a; 1930b). His publications on the freezing of different kinds of ground were most revealing in showing the difference between fine textured soils, which are susceptible to frost heaving, as contrasted with coarse aggregates that are relatively free of ground ice. Taber's work on the effect of frost heaving on roads and on the origin of permafrost in Alaska demonstrated the effect of the formation of ice lenses on frost heaving. Mining companies in Alaska have for many years dealt with permafrost in their gold dredging operations and have contributed much to the development of mining methods in permafrost areas. N.L. Wimmler's (1927) report on placer mining operations in Alaska embodies contributions of many individuals and mining 10

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS companies. Particularly significant is the description of the Miles method for thawing frozen ground by using water at natural temperatures delivered under pressure to the ground through thawing points. It was not until World War II that a more or less organized effort was made in the United States and Canada to investigate permafrost and related phenomena, especially in the relation of permafrost to various engineering structures. The construction of the Alean Highway in 1942 and the laying of a pipeline from Norman Wells to Whitehorse, Yukon Territory, Canada (the Canol Project), presented many difficulties in the actual construction and maintenance of these projects. This experience demonstrated that the engineering personnel trained in the United States have not always been able to cope with the problems because of lack of understanding of permafrost phenomena. This ignorance, coupled with the urgency and haste in the construction of projects, resulted in some wasteful failures. The rapid rotation of military engineering personnel gave no opportunity for individuals to arrive at solutions to the difficulties and to take remedial measures. About 500 miles of Alean Highway had to be rerouted in the second year of its existence because of improper selection of the original route or inability to cope with deformation that obstructed the normal functioning of the road. More than 100 icings appeared along the highway soon after it was constructed, paralyzing the normal traffic. It was at this time that the author was privileged to receive the assignment to assemble the basic data on permafrost, which could be used to help engineers engaged in construction projects in the Arctic. The hastily compiled report "Strategic Studies, No. 62" was issued by the U.S. Army Engineers in March 1943. This report (Muller 1943) was based primarily on published Russian sources and was the first attempt to bring into the English language technical terminology for this relatively new science. The report, with minor corrections, was reprinted in August 1945 and subsequently published in book form (Muller 1947). The pressing need for more information especially adaptable to Alaska and Canada led to a series of publications by the Army and civilian personnel who were exposed to the problems during the war years. A more systematic long-range plan for permafrost research was initiated in the United States by the U.S. Army Engineers and by other armed services. In 1949, the U.S. Army Corps of Engineers organized the Snow, Ice, and Permafrost Research Establishment (SIPRE), with headquarters at Wilmette, 111. In 1961 SIPRE was renamed the Cold Regions Research and Engineering Laboratory (CRREL) and transferred to Hanover, N.H. Concurrently, experimental work was, and still is, being carried on by the U.S. Army Engineers at Fairbanks at the Fairbanks Permafrost Research Area. Here, studies are being made to determine a suitable design of benchmarks. The effect of different kinds of pavement on the thermal regime of the ground is investigated by test areas. Piles of different design and depth of penetration are being studied, and the amount of force of heave is being measured. Several buildings were constructed in the research area and temperatures are being measured to learn the effect of these structures upon frozen ground. Important research work is also being carried out by the Terrestrial Sciences Laboratory, U.S. Air Force Cambridge Research Center. Since 1945, the U.S. Geological Survey has maintained a group of geologists who are assigned various field and theoretical research problems in permafrost. In

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FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS 1947, the Office of Naval Research established a laboratory for Arctic research at Point Barrow. Many scientists of diverse disciplines work from this center. Important contributions have been made to the knowledge of Arctic soils, vegetation, patterned ground, and thermal regime of the ground. The Naval Civil Engineering Laboratory at Port Hueneme, Calif., has been operating continuously since 1947 in cold-weather research. This topic required examination of sites in the Sierra Nevada, the Rockies, Canada, Alaska, and Greenland. A large low-temperature chamber at the laboratory is adequate to test heavy construction equipment at temperatures as low as -65°F. The results of the tests upon various materials enabled the Bureau of Docks to increase the usability of equipment assigned to the Arctic from 25 percent to 75 percent. Work in permafrost is also being carried on under the sponsorship of the Highway Research Board, National Academy of Sciences, and National Research Council. Finally, many institutions of higher learning on contract with the government participate in various phases of research in permafrost. In Canada, organized research in permafrost was begun in 1950 when a Permafrost Section was formed within the Division of Building Research of the National Research Council of Canada. The work is being carried on in cooperation with the Directorate of Engineering Development of the Department of National Defense. A scientific expedition to the Northwest Territories during the summer of 1951 led to the establishment of a northern research station at Norman Wells on the Mackenzie River in 1952. A study of permafrost at Aklavik in 1953 showed that the soil and permafrost conditions in that area were unusually poor from the construction standpoint and led to the investigation of a new site for the community, now known as Inuvik, on the east flank of the Mackenzie River Delta. The survey of the Inuvik area and the construction of buildings under constant observation by scientists provided an unusual opportunity to observe the effect of construction upon permafrost conditions. The effect of a small lake near Inuvik was studied through drilling operations in 1961. It was found that the ground under the lake was thawed to a depth of several hundred feet. Other significant projects that were studied for the effect of structures on permafrost conditions included the Kelsey hydroelectric plant on the Nelson River in northern Manitoba, new mining and smelting facilities at Thompson, Manitoba, drilling and sampling operations at Fort Simpson, the site of the proposed asbestos mining structure near Sugluk in northern Québec, and the study of the distribution of permafrost in the iron mines at Schefferville, Québec. The Arctic Institute of North America was organized in 1945 to encourage and promote scientific research in the Arctic and to coordinate the various research projects in the United States and Canada. The institute has at its command adequate funds to grant research fellowships in various fields of sciences pertaining to the Arctic and Antarctic regions. Information on current research on permafrost in the United States and abroad is today being assembled by CRREL (formerly SIPRE), which publishes the "Annotated bibliography on Snow, Ice, and Permafrost." This report is prepared by the Science Division of the Library of Congress. Volume I was released in September 12

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS 1951, and as of January 1960, 14 volumes had been published and more than 18,000 items recorded. Reference to sources on permafrost may also be found in the "Arctic Bibliography," which is published by the Department of Defense under the direction of the Arctic Institute of North America. It began publication with Volume 1 in 1953. It is an annotated bibliography, and the volumes carry entries of both current and historical interest, with emphasis in recent years mostly on items of current interest.

Terminology Technical terminology employed in the science of dealing with frozen ground is still in a state of formulation. While working on the first (1943) compilation of Permafrost and Related Engineering Problems, the author faced the critical problem of having no suitable terminology in the English language to express various concepts and phenomena. Because studies of frozen ground were carried out more intensely and with a much wider scope in Russia, the terminology in the Russian language had been already developed and put to use. In compiling data from Russian sources, the author was compelled to follow either of two alternative practices. Some terms were brought into English text in a literally translated form; others were borrowed through phonetic transliteration of Russian names unchanged. For example, active layer, subpermafrost water, active method of construction, and other terms were translations of the corresponding terms in Russian. On the other hand, talik,pereletok, and polyn'ya represent transliterations of Russian words. The phenomenon of permanently frozen ground has been heretofore, and to a limited extent is even now, referred to by a great variety of names composed of different combinations of the adjectives permanent, perennial, and eternal, connected by the word frozen with any one of the following nouns: soil, subsoil, ground, rock, and perhaps some others that may have been overlooked by the author. The term permafrost itself evolved during the two years of intensive study of the subject during the war. It is admittedly a vernacular term. It was severely criticized by the late Kirk Bryan, Ph.D. (1946), who proposed in its place a classical term,pergelisol. However, in spite of its etymological shortcomings, the term "permafrost" has met wide acceptance. Today, only a few purists employ the term pergelisol. As work on frozen ground in Alaska and Canada continued to progress, new demands were presented by these studies for terms that would be more appropriate, more concise, and wherever possible, more descriptive. It is in response to this new demand, for example, that the term active layer is now being replaced by active zone. This change was motivated by the fact that the thickness of seasonally frozen and thawed ground may extend through one or more physical layers of soil, subsoil, or bedrock, thus presenting a possibility of ambiguity and even confusion should a need arise to refer to these physical layers independently of the total thickness of seasonally frozen ground. Progress in the investigation of permafrost in Russia led to a critical réévaluation and revision of concepts and terminology. In the Institute of Permafrost in Moscow, a commission was organized to prepare a glossary of terms and to scrutinize these terms and the basic concepts they stand for. The results of the commission work

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FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS (Shvetsov 1956b) were published with an invitation for further discussion of the revised and newly proposed terms before their final adoption. It appears that in Russia, just as in the United States and Canada, several different terms were used by various writers for permafrost, such as icy soil, ever-frozen soil, permanently frozen soil, and perennially frozen soil. Qualifying adjectival terms were variously combined with soil, subsoil, rocks, ground, and so forth. The need for precision and for accurate recording of frozen ground phenomena was discussed by the commission, and it was brought out that differences of opinion exist among Russian workers regarding the definition of permafrost (vechnaya merzlota or simply merzlotd). It appears that, by using the term merzlota, some writers mean the phenomenon of cooling. Others designate by that term the process of cooling. Still others meant a field of negative temperature or simply the negative (subzero) temperature of the ground. The majority of workers, however, mean the term vechnaya merzlota refers to the condition or frozen state of the ground. In this sense, the term permafrost has been, and is at present, employed in the United States and Canada. The members of the terminology commission in Russia were apparently unwilling to continue the adjectival qualification vechnaya (eternal, permanent) and are now proposing a more rational adjective: mnogoletnyaya (perennial). It may be remarked that an excessively critical scrutiny of the word vechnaya (eternal, permanent) could lead to elimination of the word from our dictionaries. One may ask, are there any material objects or phenomena that are truly eternal or permanent? No matter what the answer may be, it probably could be challenged. The term vechnaya merzlota is so deeply rooted in usage that there is a serious doubt of the widespread acceptance of the new adjective, particularly in its complete form, mnogoletnyaya kriolitozona (perennial crvolithozone). An effort to replace the term vechnaya merzlota by mnogoletnyaya kriolitozona will probably meet with the same opposition as we have witnessed in this country with the attempt to replace the vernacular term, permafrost, by the classical termpergelisol. While proposing a new term in place of vechnaya merzlota, the commission left the same loopholes for ambiguity in the definition of the concept as existed before. The commission's verdict, that the science of merzlotovedeniye (permafrost) does not adequately reflect the scope of the study as it is understood today, may be open to question. By analogy, one would be hardly justified to propose a new name for the modern science of physics just because the present scope ofthat science is considerably wider than the physics of several decades ago. One might take exception to the criticism by some that the new term geokriologia (geocryology) for the science of permafrost is entirely unnecessary. The term geocryology lends itself readily to international adoption and is justifiably preferred to cryopedology, the term previously proposed by K. Bryan. As more and more scientists outside of the USSR are engaged in the investigation of permafrost phenomena and as the original Russian publications become more frequently available for study, an annotated listing of the provisionally proposed concepts and terms may be justifiably included in the present report. The terms recommended by the commission are tabulated below with their definitions. Each term is given the same number under which it appears in the published commission report. They are numbered for convenience of reference in case the reader should 14

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS desire to discuss the individual terms with the commission or to offer invited comments. The author's comments are given within inset paragraphs. 1.

Kriosfera (cryosphere): a part of the crust of the earth distinguished by its thermodynamic conditions, which includes parts of the atmosphere, hydrosphere, and lithosphère. The distinctive character of the cryosphere is its negative temperature and the possibility of either existence or presence of ice.

2.

Geokriologiya, merzlotovedenie (geocryology): the science dealing with regular freezing and thawing of the earth's crust; the development and distribution of zones of frozen soils, rocks, and grounds; and the particulars of their composition, structure, and properties. It includes associated processes and the resultant effects of human endeavor. The commission proposes this term to replace cryopedology. It will be observed in the definition of geocryology, three kinds of materials are considered—soils, rocks, and grounds, whereas in some of the subsequent definitions, only soils are involved or only grounds and rocks.

3.

Zony merzlykh porod (kriolitozony): zones of frozen rocks, (cryolithozones)—particular provinces or parts of cryosphere represented by frozen soils, grounds, and rocks. This term is to replace oblast'vechnoy merzloty (permafrost province). (a) Zona sezonno-merzlykh pochv (sezonnaya-kriolitozona) (zone of seasonally frozen soils) (seasonal cryolithozone): zone of seasonally freezing soils upon unfrozen soils. The commission recommends this term in place ofsezonnaya merzlota (seasonal frost). (b) Zona mnogoletnemerzlykh porod (mnogoletnyaya kriolitozona) (zone of perennially frozen rocks): the frozen zone of lithosphère with seasonally thawing soil existing many years (not less than three). This term is to replace vechnaya merzlota, mnogoletnyaya merzlota (permanent frost, perennial frost). There are several sources of ambiguity and confusion in the definitions given above. In the first definition, the term zone appears to be used in an areal sense, but in the definitions 3 (a) and 3 (b) the term zone appears to refer to a vertical dimension. Distinction of seasonally frozen ground resting on non-frozen ground from the seasonally frozen ground resting on permafrost does not appear to be of any practical merit or utility. It will be difficult to establish whether or not the active zone rests directly on permafrost or has a tálik directly beneath it, thereby separating it from the permafrost. It is also easy to imagine the existence of seasonally frozen ground, resting on permafrost, passing laterally within a variable distance into seasonally frozen ground resting on non-frozen ground. In such a case, two different terms will have to be used for seasonally frozen ground from place to place. Some confusion may arise from the

15

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS wording with seasonally thawing soil in the definition of permafrost. Perhaps the commission meant the frozen zone of lithosphère below the seasonally thawing soil. It is also felt that in definitions 3 (a) and 3 (b) a more general term ground should be substituted for soil. 4. (a) Preryvistost' zon merzlykh porod (kriolitozon) po vertikali (interruption in a zone of frozen rocks (cryolithozone) in the vertical direction): vertical alternation of layers of frozen rocks with unfrozen ones. The term proposed by the commission is too cumbersome, and although the earlier term (layered permafrost) is not entirely satisfactory, it is preferred to the new term. The commission will do well to ponder further on this subject and propose a better term. (b) Preryvistost' zon merzlykh porod (kriolitozon) po gorizontali (interruption in the zones of frozen rocks (cryolithozones) in the horizontal direction): peculiarities of geologic distribution of zones of frozen rocks and grounds situated in areas with frozen grounds and rocks. Until a better term is proposed for this concept, the condition may well be designated by the term discontinuous permafrost. 5.

Formirovaniye zon merzlykh porod, gruntov (kriolitozon) (formation of zones of frozen rocks, grounds) (cryolithozones): inception or origin, increase in magnitude, lowering of temperature, widening in area, and decreasing in discontinuity of frozen thicknesses. Unfortunately, the commission does not state reasons why the previously used term, aggradation, is not suitable for this concept. Perhaps a distinction should be made between the inception or origin of permafrost and the increase in magnitude and intensity. For the latter condition, the term aggradation will be used in the present report, and the inception or origin does not appear to need any special term. (a) Degradatsiya zon merzlykh porod (kriolitozon) (degradation of the zones of frozen rocks) (cryolithozones): decrease in magnitude, rise in temperature, reduction of areas, and increase in discontinuity of frozen thicknesses. This term is to replace degradatsiya merzloty Degradatsiya merzloty (degradation of permafrost) is preferred.

6.

Sezonnopromerzayushchiy sloy (sezonnomerzlyy sloy) (seasonally frozen layer): layer of soil, ground, or rock that freezes during the cold period of the year, resting on unfrozen rocks. Here again, the discarded term sezonnaya merzlota (seasonal frost) will be retained in the present report. (a) Sezonnoprotaivayushchiy sloy (sezonnotalyy sloy) (seasonally thawing layer, seasonally thawed layer): layer of soil that thaws out during the warm period of the year and rests on perennially frozen rocks. For this concept in the present report, the term active zone will be used. As has been pointed out with reference to the terms in item 3,

16

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS there appears to be some doubt about the utility of distinguishing the seasonally frozen thickness, which rests on unfrozen ground, from that underlain by permafrost. The observed behavior of ground under both conditions is about the same, and in those cases where the seasonal frost reaches down to an impervious but unfrozen layer, its behavior is identical to ground resting on permafrost. Another question is, why in definition 6, the seasonal freezing takes into consideration soils, ground, and rocks, whereas in number 6 (a) the seasonal thawing is limited only to the soil. The commission should be more consistent in referring to the various kinds of surface material on the earth's crust. It is hoped that the term "grunt" (ground) would be accepted as a general term to mean the surficial part of the earth's crust that includes pochva (soil), podpochva (subsoil), and extends to a variable depth into the gornaya poroda (rock). By adopting the general term ground, the terms soil, subsoil, and rock remain available where a specific need arises to refer to them in the scope of pedology and geology. 7.

Promerzaniye (freezing through): physical processes expressed in the penetration and spreading of the boundary of the frozen state of soils, rocks, and grounds. Perhaps this definition could be improved by referring to the physical processes that take place in the ground during its change from a thawed to a frozen state. It is also pertinent to consider that some of these processes continue to take place in the ground at various distances from the boundary.

8.

Protaivaniye (thawing): physical processes expressed in the penetration and spread of the boundary of the thawed state of soils, rocks, and ground. Comments given on definition number 7 essentially apply here. It is suggested that reference be made to changes in the ground during its passage from a frozen to a thawed state.

9.

Sloy s godovymi izmeneniyani temperatury (layer with annual changes in temperature): upper layer of the earth's crust with annual variation of temperature. It is suggested that in the definition itself the expressions verkhnyaya chast zemnoy kory—or tolshcha verkhney chasti zemnoy kory—(the upper part of the earth's crust or the thickness of the upper part of the earth's crust) be used instead of the expression verkhniy sloy. It is also hoped that the commission will make a formal proposal of a term to designate the level or the depth to which the annual change of temperature reaches below the surface of the ground, such as predel'nyy uroven' (Hi gorizont) godovykh izmenenii (Hi kolebaniy) temperatury (the level or horizon) of annual changes (or oscillation) of temperature. In this report this horizon or level is referred to as the level of zero annual amplitude.

10. Gorizont isotermicheskogo teploobmena (horizon of isothermal exchange of heat): horizon of rocks in which during a certain period of time the temperature remains constant at zero degrees or below zero degrees

17

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Centigrade because of either the crystallization of water or the melting of ice during the process of either freezing or thawing. The commission's inconsistency in mentioning in this definition only rocks, making no reference to soils and ground, is a source of possible confusion. The term itself is too long and cumbersome. 11. Geotermicheskiy uroven' teploobmena pochvy s atmosferoy (geothermal level of exchange of heat between the soil and the atmosphere): an indicator of thermodynamic balance in the interreaction between the earth's crust and the atmosphere, expressed in the temperature of rocks at the bottom of the layer of annual fluctuation of temperature. Some confusion may arise from misunderstanding or misapplication of this concept whereas the term emphasizes the level. The definition of the geothermal level brings forth the need for a concept and term to designate the "bottom of the layer with the annual fluctuation of temperature," as has been already suggested in the description of term number 10. The inadequacy of the term (geothermal level) and its definition perhaps will be corrected in the future, as it is only being provisionally proposed by the commission. 12. Kriogenez (cryogenesis): sum total of processes of physical, chemical, and mineralogical change and transformation of soils and rocks of the zone of weathering as well as of the hydrosphere at a negative temperature (temperature below zero degree Centigrade). There is some overlap between this concept and that of promerzaniye (freezing through) (see definition number 7), although in the latter definition only the physical processes are included. Perhaps a more comprehensive definition of promerzaniye (including zamerzaniye or freezing) would eliminate the need for the term and the concept kriogenez (cryogenesis). Such a comprehensive concept should probably also include the biological processes that may take place in the ground and in water bodies. It is also not made clear by the commission why consideration of processes during freezing should be limited to the kora vyvetrivaniya (zone of weathering). 13. Kriogennyye yavleniya (cryogenic phenomena) instead of Merzlotno-fiziko-geologicheskiye yavleniya (frost-physical-geologic phenomena): particular physico-geological phenomena occurring during the freezing and thawing or during the change of temperature of soils, ground, and rocks, as well as standing bodies of water and streams. For the sake of consistency, perhaps the commission should say hydrosphere instead of "standing bodies of water and streams." (a) Termokarst (thermokarst) instead ofmerzlotnyy karst, polyarnyy karst (frost karst, polar karst): a phenomenon of uneven settling or caving of soil and underlying rocks as a result of melting of ground ice. The inclusion of rocks in the definition of thermokarst raises a serious doubt as to whether thermokarst phenomena can develop in terrain underlain 18

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS by indurated rocks, with the possible exception of limestone. (b) Soliflyuktsiya (solifluction): phenomenon of slow flowage (movement) of thawed soils, grounds, and rocks along gentle slopes of relief arising from the effects of alternating freezing and thawing, the force of gravity, migration of moisture, and other processes. It is not clear if the commission intends to restrict the phenomenon of solifluction to the "gentle" slopes of the relief. It is suggested that the word "gentle" be left out of the definition, thereby removing this possible misunderstanding. By including soils, grounds, and rocks in solifluction, it would seem that this phenomenon also includes the material frequently referred to in Russian literature as plyvún (that which flows). Soil is generally thought of as the material involved in solifluction, and solifluction, itself, is generally referred to as the flowage on the surface. It would appear that to extend the term solifluction to the gravity flowage of ground below the surface (in tunnels, mining operations, and such) would be inconsistent with the original definition and prevailing usage of solifluction. There is, therefore, perhaps a need for a term to designate the flowage of ground below the surface of the earth, although the plain word "flowage" may be quite adequate. There is also a need for a term to designate this flowing ground. The term slud is a provincial English word for soft, wet mud, or mire. The corresponding Russian term is plyvún. (c) Náled (icing): a layer of either freezing water or water-saturated snow on the surface of ice in rivers, lakes, and ice fields of other origin. As currently used, Náled (icing) also includes the ice fields and freezing water on the surface of the ground as well as on rivers and lakes. (d) Taryn', Gidroeffuziya (Taryn', hydroeffusion instead of Nakip', Náled'): ice field or cover commonly composed of layered ice, which forms in the winter as a result of progressive freezing of groundwater or river water that seeps out to the surface of the ground. 14. I'dy podzemnyye (ground ice); instead of isokopaemyye I'dy (fossil ice): ice in frozen soils, rocks, and grounds; a constituent of the earth's crust as a monomineralic rock as well as a constituent part of polymineralic rock. The commission's recommendation to abandon the term iskopaemyye I'dy (fossil ice) should meet general approval, but the choice of the recommended term is not the best one. It is suggested that I'dy gruntovye, orgnmtovoi led, (ground-ice) be considered by the commission to replace I'dy podzemnye (underground ice). 15. Merzlyye pochvy, gornyye porody, grunty (frozen soils, rocks, grounds): soils, rocks, and grounds with negative or zero temperature (Centigrade), in which at least a part of the contained moisture is frozen into ice, which cements the soil particles. It should be emphasized that in this definition, the discarded term merzlota is not a synonym of frozen soils, rocks, and grounds.

19

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Merzlota refers to the state or condition of the ground without any regard to its composition, texture, degree of induration, or water content. The term merzlota is deeply rooted in Russian literature, so there is little likelihood of it being dropped by the workers in the field of geocryology. This is especially true of the term vechnaya merzlota, (permafrost), which the commission treats as the equivalent of the "zone of mnogoletnamerzlykh porod" 16. Moroznyyepochvy, gornyyeporody, grunty ("frost" soils, rocks, grounds): soils, rocks, and grounds with a negative temperature and not containing ice. It is open to question if the proposed terms, merzlyy and moroznyy will succeed in clarifying the two different concepts. The situation is somewhat comparable to the use of the English words "frozen" and "frosted," or "freeze" and "frosted." It appears that, even in the preliminary text of the commission report, the two terms are confused and incorrectly used. It is easy to imagine how a great deal of ambiguity instead of precision of ideas may result. For the lack of a better term, hopefully sukhaya merzlota (dry permafrost) will be retained among the recommended terms. 17. Talyye pochvy, gornyye porody, grunty (thawed soils, rocks, grounds): thawed out soils, rocks, and grounds. 18. Nemerzlyye pochvy, gornyye porody, grunty (not frozen soils, rocks, grounds): soils, rocks and grounds with positive temperature, which had a positive temperature for a number of years. The commission does not specifically state how long "a number of years" is. It also questions whether it is possible to prove that certain grounds have not been frozen for a number of years at some time in the past or if ground with so-called periglacial features should be excluded from this concept. 19. Sostavlyayushchiye merzlykh pochv, gruntov i gornykh porod (constituents of frozen soils, grounds and of rocks). (a) Solid (mineral, organic, or órgano-mineral aggregate). (b) Cryogenic (ice, cryohydrates, crystallohydrates). (c) Liquid (d) Gaseous 20. Kriogennaya struktura (cryogenic structure) to replace moroznaya Struktura (frost structure): composition of frozen rocks in terms of size, relative amount, shape, and orientation of component parts (mineral aggregate, crystals of ice, pores, bodies, and films of fluids and gases). The definition of cryogenic structure mentions only rocks. It is not apparent whether the omission of "soils and grounds" was intentional or not. 21. Kriogennaya tekstura (cryogenic texture) to replace moroznaya tekstura (frost texture): arrangement of frozen rocks produced by the process of freezing. The definition is too ambiguous to serve any purpose. Hopefully, the commission will bring out the fundamental difference between structure and texture. In geology and related sciences, the term structure is generally

20

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS applied to an arrangement or pattern of larger scale than that of a texture, for example, an anticlinal fold is a structure, and the bed of sandstone involved in the fold may be of fine-grained texture. 22. Summarnaya vlazhnost' merzlykh pochv, gruntov, gornykh porod' (total moisture contents of frozen soils, grounds, rocks): total contents of ice and water in frozen soils, grounds, and rocks. This definition should include moisture in the form of vapor. 23. L'distost' merzlykh pochv, gruntov, gornykh porod (ice ratio of frozen soils, grounds, rocks): contents of ice in soils, grounds, and rocks. In keeping with existing practice, it may be added that the ice ratio is generally expressed in percent of the total moisture. (a) Led-tsement (ice cement): ice that cements soils, grounds, and unconsolidated rocks without a perceptible deformation of mineral parts. (b) Led, vydelivshiysya (segregatsionnyy): prosloyki, linzy i pr. (ice, secreted [segregated]: intercalations, lenses, and such): ice that forms in soils, grounds, and unconsolidated rocks as a result of crystallization during freezing. It is suggested that the definition be expanded to read as follows: "Bodies of ice (intercallations, lenses, wedges, and such) that are formed . . ."It may be repeated here that the term gruntovoy led is preferred to the term recommended by the commission. 24. Poristost' merzlykh pochv, gruntov i gornykh porod (porosity of frozen soils, grounds, and rocks): the volume of pores occupied by gases, liquids, moisture, ice, and by other cryogenic minerals. It may be desirable to indicate that only ground that shows no evidence of deformation by included ice should be considered. 25. Kriogennyye protsessy (cryogenic processes): physical, physico-chemical, and physico-mechanical processes that take place during the freezing and thawing of soils, grounds, and rocks. It will be observed that, in the definition of cryogenic phenomena, reference was made to physico-geological features, whereas in the present definition, the term cryogenic is said to mean physical, physico-chemical, and physico-mechanical processes. A more uniform or consistent definition of "cryogenic" is desirable. 26. Kriogennyye mineraly (cryogenic minerals): minerals that exist at a negative temperature (ice crystallohydrates). A slight rewording of this definition is desirable. The following version is suggested: Minerals that form and can exist only at zero degrees centigrade and lower temperatures. 27. Migratsiya (peredvizheniye) vlagi pri promerzaniyu (migration of moisture during freezing): movement of moisture in liquid and vapor phases during the process of freezing of soils, grounds, and rocks, as well as during the frozen state of these materials. 28. Pucheniye pri promerzanii (heaving of ground during freezing): the rise 21

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS of the ground surface caused by the change in volume during freezing as a result of pushing apart of the mineral particles by the crystals of ice, formed from the water of the freezing layer and the water that migrates from asyet unfrozen layers, or by water under hydrostatic pressure. Generally the crystallization of ice at the expense of water present in pores, especially in coarse clastic aggregates such as coarse sand, does not heave the ground. Ground heaving is dominantly caused by bodies of ice such as are defined in number 14 and 23 (b). Actually, there is very little practical need to distinguish ground ice, as defined in numberl4, from segregated ice as defined in number 23 (b). 29. Usadka pri promerzanii (settling during freezing): decrease in volume of grounds, rocks, during freezing. The definition could be improved by adding "the lowering of the surface of the ground, due to the decrease in volume." The commission should consider the decrease in volume of ground from two measurable components: vertical and horizontal. 30. Pory zamerzaniya (pores of freezing): pores that form in soils, grounds, and rocks during the process of freezing because of uneven changes in volume. 31. Osadki pri protaivanii (settling /of ground/ during thawing): vertical settling of soils, grounds, and rocks due to the decrease in volume during the process of thawing. 32. Prosadka pri protaivanii (caving during thawing): local settling of ground that takes place very rapidly during thawing caused by a radical change in the structure of the ground. 33. Smerzaniye (adfreezing): process of formation and development of a bond between the freezing, moist grounds, rocks and surface of a body in contact with them. 34. Soprotivleniye smerzaniya ili prochnost' smerzaniya (adfreezing strength) (tangential): resistance of grounds, rocks that are frozen to some other object, for example, (foundation) to a shear along the plane of contact. It is not clear why the commission finds "resistance of adfreezing" preferable to the previously widely used term sila smerzaniya (adfreezing strength). 35. Mgnovennoye soprotivleniye merzlykh gruntov, gornykh porod (instantaneous crushing strength of frozen ground rocks): the maximum resistance of frozen ground or rocks to crushing. 36. Predel'no dliteFnoye soprotivienlye merzlykh gruntov, gornykh porod (bearing strength): resistance to crushing over a very slow application of the load. This review of the commission's proposals demonstrates that the terminology of basic concepts pertaining to permafrost is still in a state of flux. Many concepts and terms have not yet received the scrutiny that they deserve to attain greater precision and to eliminate sources of ambiguity and confusion. 22

P A R T

2

Permafrost Science Origin of Permafrost It is generally agreed that contemporary permafrost first appeared during the refrigeration of the Earth's surface at the beginning of the Pleistocene, or Ice Age, perhaps a million years ago. The Pleistocene age of permafrost is attested by the occurrence of frozen carcasses of mammoths and other extinct animals. It is generally believed that during the subsequent periods of climatic fluctuations corresponding changes must have taken place in the thickness and areal extent of permafrost. Permafrost can exist and, therefore, could have originated only where the mean annual air temperature is below 0°C. There are still some differences of opinion as to exactly what minimum temperature is required. Some evidence suggests that the mean annual temperature cannot be higher than -3.3°, -4°, or even -6° C, but M.I. Sumgin (1940) shows that it can, nevertheless, be quite close to 0°C. Recent studies show that the areal distribution and relative intensity of permafrost can be markedly different within short distances. Mean annual air temperature is only one of many factors that may result in a negative heat balance at a given place. PR Shvetsov (1956a, p. 25) summarizes these factors as follows: 1.

Direct or diffused solar radiation, reflection of solar radiation by the surface of the earth, transformation of radiation energy into heat energy, and irradiation of energy from the earth. All these elements combine into what may be called the radiation heat exchange.

2.

Convectional heat exchange at the ground surface and immediately adjacent air, which in turn is connected with solar radiation, atmosphere circulation, and atmospheric advection.

3.

Heat exchange between the ground surface, atmosphere, and lithosphère, connected with hydrologie cycles associated with evaporation, condensation, and sublimation.

4.

Exchange of heat in the soil, and between the soil and the lithosphère, during changes of the physico-chemical phases of water, such as freezing of water and melting of ice on the ground surface, in soil, and in underlying bedrock.

23

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS 5.

Exchange of heat in the near-surface and in deep horizons of the lithosphère, reflecting heat from the interior of the earth.

6. Heat flow of heat due to geothermal and horizontal ground temperature gradients. These processes are intimately connected with each other, producing a sum total of heat exchange with a number of variables. The climate and terrain features responsible for the origin of permafrost and its composition, structure, areal extent, intensity (relative temperature), and magnitude, are listed by Shvetsov (1956a) as follows: 1.

geographical position on the globe (longitude and latitude);

2. height above sea level; 3. relief (a topographic position with reference to slope angle and orientation); 4. vegetative cover; 5.

snow cover (its thickness, density, and time of occurrence and melt);

6. prevailing cloud conditions; 7.

origin, composition, structure, and circulation of atmosphere and water masses (the position of a given area in relation to the ocean, and the effect of wind upon air temperature and humidity);

8.

surface water (rivers, lakes, and swamps), all of which affect the temperature of the air and adjacent ground;

9.

composition and structure of the ground;

10. relative amount of moisture in the ground; and 11. groundwater and its regime (hydraulic, thermal, and chemical). Cumulative evidence indicates that under present climatic conditions, permafrost is receding or degrading. However, in exceptional cases, such as in recently formed islands in some arctic rivers, permafrost is actually forming, or aggrading. According to V.A. Moshchanskiy (1958, p. 175), meteorological observations at a number of stations in northwestern Siberia from the latter part of the last century to the present indicate that the climate has become warmer by 1 to 2.5 degrees Centigrade. L.S. Berg (1950) cites evidence that shows that, near the city of Mezen' in northern European Russia, the observed warming of climate during the first half of the 20th century resulted in a northward retreat (degradation) of sporadic permafrost for a distance of about 40 km. S.P. Kachurin (1959) makes the following observation on the degradation of permafrost in Siberia since the time of the first authentic records by A.E. von Middendorf about 100 years ago. One of the points where Middendorf made geothermal measurements down to the depth of 41 ft. was in the vicinity of Staro-Turukhansk. He regarded the position of Turukhansk as being on the southern 24

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS border of the permafrost province. Since that time, no new observations on permafrost had been made in the area of the middle course of the River Yenisey. For this reason, on all previous maps, the southern boundary of permafrost was drawn with a sharp bend to the north at Turukhansk and then turned sharply to the south, running in almost a straight line along the right bank of the Yenisey River, thereby reaching a considerable distance south of the city of Krasnoyarsk. All attempts to explain this bulge in the permafrost boundary were based only on suppositions. The uncertainty that surrounded knowledge of the southern boundary of permafrost in the Yenisey river basin led to the organization, in 1937, of an expedition to investigate permafrost along the left bank of the Yenisey River. It was also intended to revisit and restudy localities first examined by Middendorf. This study was also undertaken to obtain factual data on the degradation of permafrost that had been theoretically proven by M.I. Sumgin, based on his observations on permafrost at the experimental station of Skovorodino. This question has both theoretical and practical significance. Depending upon whether permafrost is aggrading or degrading, the principles of engineering construction should be adapted accordingly, either to retain existing permafrost (passive method of construction) or eliminate it (active method of construction). The results of the expedition showed that the southern boundary of permafrost should be drawn approximately 250 to 300 km to the south of Turukhansk. This meant that, in the vicinity of the Yenisey River, only occasional táliks existed. Degradation of permafrost is also indicated by landscape features and by the ground structures found in areas peripheral to permafrost regions where no permafrost is found today. Deformation of the near-surface layer of the ground shows features characteristic of the process known as cryoturbation, that is, soil flowage that takes place upon melt of ground ice. Subdued polygonal patterns also suggest melt of former ice wedges with resultant "mound" topography. While permafrost degradation is the prevailing trend today, there are conditions under which permafrost can form now. These conditions have to promote a negative heat balance. Figure 4 shows diagrammatically such a possible set of conditions, where a substantial layer of peat and moss materially affects the heat balance between the atmosphere and the ground. In spring, heat flow into and out of the ground is balanced. In summer, the dry peat and moss has a coefficient of heat conductivity only one-tenth that of wet peat and moss. These materials retard the flow of heat from warm summer air into the ground. In autumn, the conditions are again more or less balanced, but in winter the frozen peat and moss loses its insulating quality, resulting in substantial heat loss from the ground. Thus, during one year, the heat balance in the ground will be negative. This condition may be further modified in one direction or another by the presence of snow either during the early winter or late winter. These relations are illustrated in Figure 5. Evidence from both the USSR and the United States indicates that there are at least two generations of permafrost. A.A. Zemstov (1958, p.194) came to the conclusion that in the West Siberian lowland there are two kinds of permafrost. One, near the surface, owes its origin to the present climate. Another, at depth (relict permafrost), originated in the preceding glacial epoch and has its upper surface at depths ranging between 60 and 230 m. 25

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 4. Flow of heat between air and ground in tundra country.

Similar occurrences of deep (relict) permafrost have been established on the right bank of Ob' River. Based on the study of a number of drill cores, deeper permafrost in the Salekhard region is separated from the near-surface permafrost by a thickness of ground that varies from 20 to 100 m and in which temperature is above 0°C. In North America, studies of permafrost in Alaska by T.L. Péwé and D.M. Hopkins reveal the presence of two generations of ice wedges, the younger one often transecting the older one.

26

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Figure 5. Effect of snowfall in different seasons on the flow of heat between air and ground in tundra country.

Geography of Permafrost Permafrost underlies about one-fifth of the entire land surface of the world. It is most widespread in the Northern Hemisphere around the shore of the Arctic Ocean but is also extensive in the Antarctic. It is found in almost half of the territory of the former USSR, from the Arctic to northern Mongolia and Manchuria. This is an area considerably larger than the entire United States. Permafrost also underlies half of Canada and more than 80 percent of Alaska (Figure 6). The contemporary temperature and areal continuity of permafrost provide a basis for the classification and mapping of permafrost. One speaks of continuous permafrost where ground below the active zone is frozen over a wide area, without any islands or channels of thawed ground (táliks). This condition prevails in the extreme northern part of Eurasia and North America, as shown on Figure 6. Progressing southward, small areas may be encountered that remain unfrozen throughout the year. These bodies of ground (táliks) occur as isolated nests, lenses, or intercalations within the permafrost. Their origin and continuous existence is generally associated with either relatively coarse textured material that is permeable to groundwater or to limestone perforated by solution channels. It will be remembered that flowing or percolating water carries a store of heat, the amount of which, depending on the volume of water and its temperature, may prevent certain parts of the ground from freezing (Figure 7).

27

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 6. Distribution of permafrost in the Northern Hemisphere.

A gradual increase southwards in the frequency of islands or intercalations of táliks is observed until the prevailing pattern in the areal distribution of permafrost consists of moderately large areas of permafrost, continuous or with islands of táliks, alternating with moderately large areas of thawed ground with occasional islands of permafrost. Finally, near the southern limit of permafrost occurrence, the terrain consists entirely of thawed ground with only occasional intercalations or islands of permafrost. As a result, no precise boundaries can be drawn between the four types of areas of permafrost indicated above. As only a few control points are available in North America to establish the relative extent of permafrost (Brown 1960), the boundaries between the different divisions shown on Figure 6 represent only approximations, and the thicknesses 28

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 7. Cross section through the Gorodskaya Protoka (channel of the Lena River) at Yakutsk showing extent of permafrost (after Svetozarov 1934).

indicated are not intended to apply to Canada and Alaska. It is also not certain how far south permafrost extends along the Canadian Rockies and the Rocky Mountains in the United States. A recent discovery of permafrost at the summit of Mt. Washington in New Hampshire at an elevation of 6,288 ft. suggests that perhaps isolated areas of permafrost might occur at high altitudes in the Rockies farther south beyond the area marked in Figure 6. The temperature of permafrost has also been used to distinguish areas of varying intensity. For example, M.I. Sumgin (Figures 8 and 9) associated the area of continuous permafrost with temperatures lower than -5°C at 10 to 15 m depth. According to Sumgin, in areas of occasional islands of táliks, the ground temperature at 10 to 15m depth generally varies from -1.5 to -5°C. In areas where permafrost with islands of táliks grades into thawed ground with islands of permafrost, the temperature at 10 to 15 m depth is generally higher than -1.5°C. In addition to the areal (horizontal) extent of permafrost, its vertical distribution provides an additional basis for distinguishing different kinds of permafrost. Besides the actual measurement of thickness, which may vary from a fraction of a meter to 600 m, permafrost may be uninterrupted in the vertical direction, or it may have layers of thawed ground. Thus, we may distinguish between uninterrupted and layered (interrupted) permafrost. Some confusion may arise from the use of such similar terms, referring to the horizontal and vertical continuity and the horizontal and vertical discontinuity of frozen ground. However, consistent use of the term continuous and discontinuous permafrost with reference to its horizontal extent and interrupted ("layered") and uninterrupted permafrost in describing its vertical extent will hopefully minimize confusion or ambiguity. The interrupted or layered permafrost generally reflects the textural composition or differences of ground. Commonly, it is the less pervious layers that tend to remain permanently frozen; the porous or permeable deposits are likely to be thawed (táliks). 29

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 8. Permafrost map of Eurasia (from Sumgin 1940).

Figure 9. Diagrammatic section through Siberia, from the Arctic Ocean to the Sea of Japan, showing relative thickness of permafrost and the active zone. Boundaries between frozen and unfrozen bodies, thus, more or less coincide with lithologie boundaries. Interrupted permafrost may occur locally, due to a special condition of accumulation of sediments. For example, in valleys, the accumulation of deposits during the flood period, combined with climatic variations from year to year, may result in burial of a thawed layer, which, because of its greater permeability, may remain unfrozen. In contrast, any less pervious superjacent and subjacent material may freeze and remain

30

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 10. Permafrost map of Eurasia (from TumeP, 1946).

frozen for many years. Interrupted permafrost on a larger scale may reflect changes of climatic conditions in terms of climatic cycles of many years' duration. A unique occurrence of permafrost is recorded in polar seas at variable depth beneath the water (Figures, 8, 9, 10, 11). Mathematical analysis of the heat flow between the earth and the ocean water by A.M. Lachenbruch (1957) led him to conclude that: ...Along the Arctic Coast of the North American mainland, a few thousand feet offshore, permafrost is not expected to occur at depths below the sea bottom greater than 200 to 300ft. unless the shore line has undergone large transgressions in the last few thousand y ears. If the shoreline has been stationary, or regressing, permafrost depths are not expected to exceed 100ft. at points more than 1,000 to 2,000ft. offshore. Valuable information regarding post-Pleistocene shoreline movements can be obtained from temperature measurements to depths of a few hundred feet in the vicinity of the present shorelines. Preliminary interpretation of data from Barrow, Alaska, indicates that the thermal effect of the ocean is so great that the shoreline there probably has been relatively stable for the past few thousand years. It is highly unlikely, therefore, that oceanic permafrost of the type indicated by Black occurs there. At Cape Simpson, however, about 60 miles east of Barrow, preliminary thermal results suggest that an active transgression might be taking place. These conclusions are consistent with geomorphic evidence from the two areas. 31

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 11. Permafrost map of Eurasia (from Baranov 1959).

The expanded exploration and intensified exploitation of the Soviet Arctic have furnished increasingly greater amounts of basic data to map the areal extent of different kinds of permafrost. The degree of progressive refinement is quite apparent from the comparison of M.I. Sumgin's map of 1940 (Figure 8) with the 1945 map by V.P. Tumel' (Figure 10) and again with I. Ya. Baranov's 1956 map (Figure 11). In addition to temperature and thickness, a permafrost map should also depict the nature and thickness of surficial material. This is useful for terrain evaluation. Only a few such maps are available for parts of Alaska; perhaps coverage in the permafrost province in the USSR is greater. Recent work of T.L. Péwé (1958) in the Fairbanks quadrangle, Alaska, shows a detailed analysis of the terrain from the standpoint of occurrence of permafrost. Such evaluation should be extended to other parts of Alaska, to other types of geomorphic provinces, and should be supplemented with test drilling data, giving the thickness and temperatures of frozen ground.

Vertical Extent and Temperature of Permafrost The vertical extent of permafrost varies from place to place from several meters to more than 500 m. The greatest thickness of permafrost yet encountered was near Nordvik, along the Arctic coast of Siberia, where 600 m of frozen ground was penetrated in drilling operations. At Amderma, in the Arctic part of European Russia, permafrost was extrapolated to be about 400 m thick. As might be expected, permafrost becomes progressively thinner when traced southward, until it completely disappears along the southern boundary indicated on the maps of Figures 8, 10, and 11. In Alaska, a thickness of 300 m of permafrost was encountered on the coastal 32

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS plain north of the Brooks Range. Permafrost is much thinner south of the range, and is altogether absent south of the ranges along the Alaskan Coast. In high latitudes, where permafrost is relatively thick, its thermal profile (gradient) swings to a considerably lower temperature than in the vertical profile along the lower latitudes. In the far north, temperatures as low as -8°C and even lower are not uncommon, whereas along the southern border of the permafrost province ground temperatures hang in a very delicate balance close to 0°C. Local variations in the thickness and temperature of permafrost may be quite marked, depending upon the nature of the ground, its surface slope and orientation, vegetation, and the amount and period of snowfall. At a given place, the temperature of the permafrost shows relatively small variation with depth. Seasonal variations extend into permafrost only to a depth of from 15 to 30 m, depending upon the nature of the ground, particularly its heat conductivity. The range or amplitude of this seasonal variation diminishes downward and comes to zero at a level which the Russians call the level of zero annual amplitude or, in short, the level of zero amplitude. This horizon is also known as the depth of seasonal change. Below the level of zero amplitude, the temperature of the permafrost has a profile (gradient) that remains stable from season to season, and from year to year. The temperature may continually rise with depth until the unfrozen ground is reached below the permafrost, or it may first show a further decline and then a rise. The greatest fluctuation of temperature takes place in the active zone and is the main cause of damage to buildings, excavations, pipelines, and other engineered works.

Ground Ice The term ground ice applies to all bodies of more or less clear ice in permanently frozen ground and in the active zone. A.E. Leffingwell (1919, p. 180) did not consider buried glacial ice as ground ice, but on this point there are differences of opinion. In this report buried glacial ice that lasts many years is regarded as a kind of ground ice. In the past, ground ice has been variously designated as underground ice, fossil ice, subsoil ice, subterranean ice, ureis, bodeneis, and other similar terms. All these terms are here relegated to synonymy with ground ice. Ground ice can be encountered at only a few centimeters below the turf or it may lie at depth below the surface, and it can occur as lenses, veinlets, or large ice bodies (Figure 12). Where the ground ice is devoid of vegetation, the late summer thaw extends to a greater depth, and the ground ice is encountered farther below the surface. According to the origin and mode of occurrence, ground ice may be differentiated into four main types: 1.

Buried ground ice

2.

Segregated ground ice

3.

Emplaced ground ice

4.

Interstitial ground ice

The distinction between these different kinds of ground ice cannot always be 33

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 12. Ground ice occurrence: A: Lenses or intercalations, and veinlets, of ground ice near Whitehorse, Canada (courtesy of the U.S. Army Air Force). B: Lenses and wedges of ground ice exposed by hydraulicking in the placer mining operations near Fairbanks, Alaska (courtesy of the U.S. Geological Survey). C: Experimental freezing of sand (left) and clay (right) in an open system (approximately one half natural size): (left) Frozen cylinder, half sand, half clay. Much segregated ice in clay but not in sand, (right) Differential displacement of cylinder due to segregation of ice in clay but not in sand. Cavity caused by displacement of relatively dry sand (from Taber 1930).

sharply drawn, as some ground ice may owe its origin to more than one cause, and as far as the mode of occurrence is concerned, there are generally gradational types present that can be separated only on the basis of a more or less arbitrary judgment. Buried ground ice, also sometimes referred to as fossil ice, is not always easily identified, but there are cases, for example in the New Siberian Islands (Klenova 1948), where cliffs of from 35 to 40 m of clear ice appear to be unmistakably buried remnants of glacial ice. It is also known that this buried ground ice extends for some distance from shore at the bottom of the Arctic Ocean where it is covered by only a thin layer of mud. 34

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS A large lens of ground ice in Greenland was found to contain crudely stratified grains of sand and dust, which under a microscope showed good rounding and frosting of the surfaces, suggesting a wind-blown (aeolian) origin. The lens in question is presumed to represent a buried snowbank that subsequently recrystallized into clear ice, except for the inclusion of the scattered wind-blown material. Buried ground ice may also originate through burial of standing water (ice) by winter dust storms or in early spring by alluvial mud during the spring flood. The burial of standing water may also be accomplished by the spread of peat-bog conditions over a lake with the ultimate increase in the insulating blanket to the extent where the summer heat fails to thaw out the winter ice beneath this blanket. Along the seacoast in shallow and sheltered areas with steep cliffs bordering the shore, blocks of sea ice may be thrust against the cliffs and may subsequently become buried beneath material that slumps from the adjacent cliff during the summer thaw. Segregated ground ice may occur in scattered specks or blotches or, again, in more or less continuous lenses, veins, and sheet-like intercalations (see Figure 12A). Ground ice in thin and closely spaced intercalations with silt, sand, or clay is called by T.L. Péwé ice gneiss (oral communication). Bodies of segregated ice generally form at the expense of interstitial liquid moisture around a nucleus ice crystal. Locally, freely percolating water in certain strata (aquifers) may contribute a significant amount of water to form a large body of ice. This process can be further enhanced if the water in the aquifer is under hydrostatic pressure. Segregation of ice lenses and veins in a moisture-containing ground has been experimentally performed by many workers, particularly by S. Taber (1929, p. 456) (see Figure 12B). Taber's experiments show that "in indurated clay, or clay that has been thoroughly consolidated artificially, the layers of segregated ice are clear, for the most part, and very sharply separated from the frozen clay. The total thickness of these layers, as close as can be measured, is the same as the amount of surface uplift." From this, it may be concluded that the heaving of clayey ground is caused primarily by the growth of ice layers that draw on the supply of additional water from the capillaries of adjacent (water-saturated) ground. This condition, under which an additional supply of water is available during the process of freezing, is known as an open system. It contrasts with a closed system under which the freezing ground has no access to an additional supply of water from without. The redistribution of moisture and the formation of segregated ground ice has been experimentally studied by A.P. Bozhenova ( 1957), who demonstrated the marked effect of partial or local insulation of the ground (by sawdust, vegetation, snow, and such) during freezing. The presence of a partial or local heat-insulating cover brings about a regular redistribution of moisture as shown in Figure 13 A/B/C. In sandy clay, ice lenses form in the upper part of the ground, which is not protected by the insulating cover, and the ground below the insulation loses some of its moisture. In the saturated, sandy material, additional moisture accumulates beneath the insulating cover with the formation of ice lenses, which draw upon the water from the exposed part of the ground and from the underlying ground beneath the insulation. In sandy ground with moisture content below saturation, the redistribution of moisture during the process of freezing is similar to that of sandy clay. The moisture migrates in the 35

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

DIAGRAM OF MIGRATION OF WATER IN SANDY CLAY DURING FREEZING. WITH INITIAL MOISTURE OF 39%

Figure 13. Diagrams showing nature of water migration in: (A) sand with initial moisture of 13 percent; (B) sand with initial moisture of 20 percent; (C) sandy clay with initial moisture of 3 9 percent.

36

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS direction of the ground, which is not protected by insulation, without reaching the supersaturation stage. Emplaced ground ice includes a wide variety of shapes and dimensions of ice in which the dominant source for the ice is either an inflow of water or an accumulation of snow. The water that emplaced ground ice is formed from may come either from the surface of the ground or from subterranean sources. One occurrence of ground ice is known as an ice wedge. Ice wedges represent a network of semi-vertical sheet-like masses that dip downward so that when they are exposed in a vertical section they appear as wedges. Ice wedges range from a few centimeters to several meters in width and have been seen to extend downward 3 m with a possible continuation for a distance of another 5 or 6 m. The blunt surfaces of ice wedges generally lie directly below the active zone, which may be from a few centimeters thick to more than l m thick. Ice wedges most commonly occur on the level surface of coastal plains and on the flood plains of larger streams. They are usually associated with fine clastic sediments such as muck, clay, and silts with various proportions of organic admixture. Occasionally, ice wedges have been found in coarse sands and gravels. In plan view, ice wedges generally form a polygonal pattern, and may or may not be expressed at the surface of the ground by slight relief. Their exposure in a riverbank or in a sea cliff may appear quite irregular. The front face of the exposure, cutting obliquely across the wedge, gives an exaggerated picture of its size and the inclination of the sloping sides. Where the face of the bank parallels the path of the wedge, the exposure may appear (and has been on many occasions misinterpreted) as a continuous massive layer of ice. A diagrammatic representation of ice viewed at different angles of exposure is shown in Figure 14. Ice wedges form in contraction fissures, which open up as the ground shrinks during the cold winter season. With the coming of summer, melt water seeps into the fissures and, coming in contact with ground that is still frozen, turns into ice. Locally, snow may contribute a substantial amount of moisture, filling the cracks during the winter. The stresses set up in the ground with the changes in temperature, which are responsible for the formation of contraction fissures, have been demonstrated by B.N. Dostovalov (1957), who illustrates the stresses and deformation using a solid cube, ABCDEFG (see Figure 15A). When the temperature is the same in all points of the cube, no stresses originate in the solid, and it retains its cubic shape. With freezing of the cube from the top, the upper layer ABCD tends to contract to the dimensions of A'B'C'D', but the underlying layer with higher temperature and larger area prevents the top layer from assuming this contracted size. The interaction between these layers causes stresses. The upper layer is subjected to tension by the lower layer, and the lower layer is subjected to compression by the upper layer. The same relationship exists in any two adjacent horizontal layers except for the uppermost surface layer, which is subjected to considerably greater tension than the inner layers. These forces produce deformation of the cube, with every horizontal layer undergoing shearing directed towards the center point. The surface ABCD becomes concave and will eventually occupy position A'B'C'D', and the surface EFGH becomes convex and will eventually occupy the position E'F'G'H'. Thus, during ground freezing from 37

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 14. Diagram of ice-wedge exposures in an undercut bank of polygonal tundra (modified from Leffingwell 1919).

the top, each element of frozen ground is subjected to tensional, compressional, shearing, and bending stresses. Analogous deformations take place in clay grounds during their drying, producing concave mud chips separated by mud cracks. The following analysis was offered by B.N. Dostovalov (1957) as a means of computing the stresses in the ground as it freezes (Figure 15B). The frozen mass is shown in the lower quadrant of rectangular coordinates XYZ, with free surfaces in the planes of YZ and XY. The temperature is indicated by the curve on the right-hand side of the figure. In the layer of thickness Z = h, all upper elements of volume will tend to contract relative to the lower element of the edge O Y and move to the right the distance OB. At the same time, tensional stresses originating in the ground will be balanced within the limits of elasticity by cohesion forces. These stresses are designated tx in the section parallel to the surface YZ, at distance x from this surface. These stresses are regarded as tangential as applied to the surface of the ground. This problem cannot be solved by statics, as the only quantities are the equality and the opposite direction of forces at any point of the cross section. For this reason, use is made of the principle of superposition of deformation. The frozen ground is cut along the plane parallel to the plane YZ at the distance x from this plane. Under these conditions the forces of cohesion will not balance the forces of tension. In the stressed layer of ground sliced away from the main mass, a shearing deformation will take place, and the line BD will move to the left the distance S = 1A of OB, into the position AC. If all the horizontal layers of the part of the ground that was cut off could move freely relative to each other and were not stretched out, then the length OB could be regarded as the contraction of the length x, during the cooling, A5 = Sh - 8o OB = 2S = a x A O

(0)

where alpha is a coefficient of linear contraction of frozen ground. But OB is actually less than 38

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 15. (A) Diagram illustrating deformation of a cube of ground. (B) Stresses in the upper layer of frozen ground. (From Dostovalov, 1957).

39

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS a x A 0 and one can equate these two quantities by multiplying a times x A 5 by a coefficient n, which is smaller than 1, making: (1) If we now restore the action of cohesion forces, they will produce shear deformation in the opposite direction, with the absolute displacement again equal to S. It is known that the absolute displacement S is connected with the shearing tangential force Q through the following relationship: (2)

where h is the distance from the fixed plane of the surface, which is parallel to it and along which acts the force Q (in our case h = z); F is the surface along which acts the force Q (in this case F = x y); G equals E over 2(1 + u), which is a modulus of elasticity during shear, wherein term E is Young's modulus, and y is Poisson's coefficient (ratio). Equating S from (1) and (2), we obtain an equation for determining the force Qx, which acts in the direction of x: (3)

from which we obtain (4)

Substituting for the force Qx, tangential stress and having in mind that A ô over h = degree oz, finally: (5) In computing the gradient o, which is equal to A 0/h in Equation 5, for normal temperature of the stressed mass one assumes the temperature at the depth of zero annual amplitude, then layers at a higher temperature will be relatively expanded and compressed, and at lower temperatures relatively contracted and stretched. In this manner the tangential stress TX in a freezing mass in the presence of free vertical surface XY is proportional to the temperature gradient along the vertical, degree z o, at a distance x from the free vertical surface, to the modulus of elasticity during the shear G and to the coefficient of linear expansion (contraction) of frozen ground a. The coefficient of proportionality in Equation 5 is approximately equal to !/2 n, with the coefficient n at small deformation, differing little from 1. Equating TX to the temporary resistance during the shear ib from Equation 5, we can compute the distance xb from the free vertical surface at which the tangential stresses will reach their limiting values and a tear will occur (that is, the fissure will appear). This distance is equal to: (6) Calculations show that the distance between parallel fissures, obtained using Equation 6, will agree with observations in nature. With a sufficiently large linear dimension of the mass, and with a temperature gradient greater than zero, the stress will always exceed the temporary resistance, and fissures will appear. In the case of homogeneous masses, the direction of fissures 40

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS will be rectilinear. After the formation of the first fissure, there follow significant quantitative changes in the process of fissuring: the mass of the ground breaks down into two parts, with each part having two free surfaces, horizontal and vertical. The appearance of the free vertical surface YZ determines the deformation of the shear, which partially decreases the stress, with this decrease being proportionalto the angle of shear. Farther away from the free surface, the angle of the shear will decrease and the stresses will increase until they again reach the limiting value of the temporary resistance. In a homogeneous material, the distances from the first fissure—on which the stress reached its limiting values—will be the same. Therefore, the second fissure will occur parallel to the first. In this manner, the surface of a homogeneous mass will be broken up by parallel fissures into a number of bands of equal width. The shearing along the surfaces of these bands will enable the ground to undergo some deformation without tears in the direction along the bands. For this reason the transverse tears appear at distances that exceed xb, and the homogeneous ground cooled from the surface must be broken up by fissures—not regular squares but regular rectangles in which the shorter sides form later than the longer sides. The fissures facilitate further cooling of the ground. Although the surfaces of even temperature distribute themselves parallel to the walls of the fissures and along the horizontal surface of the ground, directions of greatest temperature gradient are normal to them. Because stresses are directly proportional to gradient, the greatest stresses develop in the direction of greatest temperature gradient. Therefore, a secondary set of fissures forms in the direction normal to the first (that is, longitudinal). Thus, at the junction of fissures, the fissures that form the base line have opened earlier than or prior to the fissures perpendicular to them. This is the manner in which large-scale patterned ground is formed. Where the temperature gradient is small, the resultant rectangles are large. If the temperature gradient increases, however, progressively smaller and smaller rectangles are formed. In this manner the dimensions of polygons serve as indicators of maximal gradients and minimal temperatures, that is, the sharpness of temperature fluctuations. In the prismatic blocks thus formed through cooling, bending stresses are developed that also increase progressively with distance, but in the vertical direction (Figure 15A). Thus, at certain depths horizontal fissures should form along the planes that are parallel to the top surface, and the frozen homogeneous mass should separate into rectangular blocks. The formation of such blocks in response to thermal stresses has been observed in massive rocks. The "curling up" along the bottom of blocks of frozen ground produces open spaces in a more or less horizontal plane in which large ice lenses can form. In a recent study of contraction-crack polygons, A. Lachenbruch (1960a; 1960b) claims that the orthogonal system of fissures is characteristic "of somewhat inhomogeneous or plastic media," as contrasted with non-orthogonal fissures produced by a "uniform cooling of very homogeneous relatively nonplastic media." Among the orthogonal polygons Lachenbruch recognizes a random orthogonal system and an oriented system. In his opinion, most of the oriented orthogonal polygons are formed by horizontal thermal gradients near the edge of gradually receding bodies 41

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 16. The stages of pingo growth: (A) early stage; there is the beginning of a bulge in poorly drained polygonal ground (photo by S. W. Muller); (B) "mature" pingo; the growth of the ice core ruptures the ground surface, exposing the ice. Melt of the ice produces trickles of mud along radiating cracks, giving the impression of a "mud volcano" (photo by S.W. Muller); (C) "mature" pingo (canoe in the foreground), Mackenzie Delta region, Canada (photo courtesy of J. Pihlainen); (D) pingo in the late stages of the cycle, near complete disappearance (photo by S.W. Muller).

of water, such as slowly draining lakes, shifting river channels, or along topographic irregularities underlain by materials of anisotropic horizontal tensile strength. Perhaps the most impressive manifestation of emplaced ground ice is found in cores of giant mounds, called pingos (Figure 16 A-D). These are also known as hydrolaccoliths and as bulgunyakhs in Yakutiya. They are common along the arctic coastal plains in North America and Eurasia. Generally, they occur in poorly drained areas, near river deltas, and occasionally rise in the middle of a lake. Pingos 30 to 50 m high and several hundred meters across are not uncommon. Some pingos in Siberia are said to be 100 m high with a perimeter of about 1,000 m. F. Müller (1959) reported that drill holes down to 13 m in the center of a pingo in Greenland failed to reach the bottom of ice. Similar observations were made by J.A. Pihlainen (Pihlainen et al. 1956) on a Mackenzie Delta pingo, which had less than l m cover of soil at the summit and was underlain by more than 10 m of ice. Pihlainen reported that on the flat ground adjacent to the pingo a drill hole of 7 m did not encounter any ice. 42

FRO/I-;N ¡N Ti MI-:: PERMAFROST AND ENGINEERING PROBLEMS Pingos generally have a regular conical shape with radiating fissures at the summit. They are formed by the growth of a large ice lens from a fraction to 20 m below the surface. The radiating fissures at the summit are produced by the rupture of the overlying cover by the bulge of the ice lens during its growth. After reaching a certain height the fissures open sufficiently wide to expose the ice core and cause the ice to melt. A trickle of liquid mud or of clear water from the summit of a pingo gives the impression of a mud volcano. As the ice continues to melt, the rim of the summit recedes and forms a lake in the middle of the pingo. This lake may or may not have an outflow, depending upon whether or not a subterranean source of water is available. With progressive melting of ice, the pingo may completely disappear. It is generally recognized that the cycle of formation and disappearance of a pingo takes many hundreds or thousands of years. Recent studies of pingos in East Greenland by F. Müller (1959) reveal that the percolating water through an unfrozen aquifer (tálik) accelerates the melting of ice in the core of a pingo. This continued inflow of water from beneath also results in outflow from the center of the pingo, eroding its rim and modifying its original symmetrical shape. As yet, little is known about either the origin or mechanics of pingo formation. The hypothesis, based on theoretical considerations, that some may be the result of a diapiric implacement of ice (that is, injection of ice from below into the overlying ground) remains to be substantiated by field evidence (Müller 1959). Smaller ice-cored mounds may form on gently sloping ground. Such mounds may either remain confined or may burst open and allow supercooled water to outflow on the surface of the ground (Figure 17). Such ice mounds produced by localized hydrostatic pressure of groundwater are referred to as FROST BLISTERS. Although frost blisters generally form within the active zone and, strictly speaking, do not fall in the category of ground ice, some of them bring about a change in the thermal regime in the overlying ground cover and retain their ice core for many years. Many different terms have been proposed to designate the various types of ice mounds. Indiscriminate use of these terms has caused confusion and makes it difficult to analyze and comprehend the true nature of these phenomena. There are, undoubtedly, many different types of mounds in existence whose origin, morphology, and history are distinct. In only a few cases, however, have these been thoroughly studied and objectively described. To minimize further confusion, it is proposed that the term frost mound be applied to all mounds produced by frost action, unless their specific character, origin, and structure are known. Another type of emplaced ground ice has the appearance of ice conglomerate or ice concrete (icecrete). It contains lamina of soil, fragments of rocks, and pieces of peat. The volume of ice generally exceeds that of rocks and soil inclusions. This type of ground ice is generally found on sloping surfaces directly below the active zone (Figure 18*). S.P. Kachurin (1946) explains the origin of this ice conglomerate *Editors note: "Figure 18 was included in the manuscript but was not referenced. It is a rework of Figures 76 and 81 that appeared in the earlier 1943 and 1947 versions respectively where it was used in the context of determining the thickness of the active layer. Here, we believe it was intended to be used to describe the ice-rich zone at the base of the active layer (the so-called 'transient' layer of Y. Shur and others). The reference to Guberov is not cited. We are unable to verify the role that Muller intended for Figure 18).

43

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Mound is ruptured by hydrostatic pressure (and crystallization of ice?)- Water freezes forming icing and ground ice, Occasionally s hollow space is left in the cor© of a mound,

Figure 17. Diagram illustrating formation of a frost blister. The mound is ruptured by hydrostatic pressure (and crystallization of ice?). Water freezes forming icing and ground ice. Occasionally, a hollow space is left in the core of a mound (after Nikiforoff 1928).

44

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 18. Moisture profile of frozen ground indicating approximate level of permafrost table (After Guterman)

Figure 19. Diagram showing ice ratio as percent of total moisture in different types of ground at various temperatures (after Tsytovich 1958). 45

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS as follows:

A certain flow of water below the active zone takes place from the upslope towards the lower place along the profile gradient. The material in the active zone is susceptible to some internal deformation and redistribution of particles, particularly if there is some, no matter how slight, unevenness of the permafrost table. In such cases, dilated ground, slud in the lower part of the active zone, may, by gravity, flow in or wedge itself in between the active zone and permafrost. Locally, a build-up or thickening is produced in the active zone and has a retarding effect on the rate of penetration of frost (loss of heat) with the result that a confined lens of moist ground will remain unfrozen under this (hummocky) thickened active zone. The water from the still unfrozen lens will gradually form a lens of ice at the underside of the bulge until the entire supply of moisture is exhausted. According to S.P. Kachurin, this process will produce a noticeably thicker lens of ground-ice than when there is freezing of an active zone with uniform thickness and under uniform conditions. Interstitial ice includes minute particles of ice that form in the interstices of ground without segregating into perceptibly distinct masses. Although this type of ground ice is the least conspicuous, its effect on the mechanical properties of ground is highly significant. Through testing of field samples and on the basis of experimental work it has been shown, during recent years, that when the ground freezes not all the original moisture passes from the liquid into the solid phase (ice) (Tsytovich 1957b). The ratio of the weight of ice to the weight of all the moisture in the ground (L'distost ' = icicity or iciness—here termed ice ratio) at 0°C and lower temperatures varies within a wide range of limits, depending upon the texture of the ground, temperature, and pressure. As can be seen from Figure 18, in a coarse-textured material such as sand, almost all (99 percent) moisture passes into the solid phase (ice) at a temperature slightly below 0°C, whereas in a silty sand an active change of phase continues down to -2°C, at which point a sharp slowing down in conversion of water into ice takes place and continues with barely perceptible change down to 0°C. At this point, slightly more than 95 percent of water has passed from the liquid to solid state. A more striking picture is presented by the behavior of clay that has only 70 percent ice ratio at the temperature of-1°C and has to be frozen to -30°C to attain the ice ratio of 80 percent. The content of liquid water in frozen ground is also controlled by the specific surface of the aggregates, by the chemical and mineralogical composition of the aggregates, as well as by physico-chemical properties of dissolved salts. The effect of a specific surface is clearly brought out by Z.A. Nersesova and I.A. Tyutnov (1957). Table 1 shows the difference in the relative amount of liquid water in the different fractions of quartz sand. The liquid phase of water in this table is shown in percent of the weight of dry ground. The high percentage of liquid water in the size fraction 46

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Table 1: Liquid and solid phases of water in frozen quartz sand of different textures. Liquid phase of water is given in percent to dry ground. Source: Nersesova 1957.

Temperature (°C) -02, -0.3 -0.5, -0.6 -1.0, -1.3 -2.0, -2.1 -4.5, -5.1

Fractions 1.0-0. 5mm Moisture by weight = 16% Ice ratio Liquid phase of (%) water (%)

Fractions 0.05-0.01 mm Moisture by weight = 39% Liquid Ice ratio phase of (%) water

98 99 100 100

3 3 2 2 0

97 97 99 99 100

(%) _ 1.1 0.9 0.0 0.0

Fractions O.001 mm Moisture by weight = 57% Liquid Ice ratio phase of (%) water

80 90 95 97

(%) 14.2

6.4 2.8 2.0

Table 2: The effect of pressure on the amount of liquid water in frozen ground. Experimental work shows that even a slight pressure of 2kg/cm2 results in more than 10 percent difference of ice ratio as compared with the test when no pressure was applied during the freezing. Source: Tsytovich 1957.

Temperature Type of ground inC° Sandy clay Below 0° (not measured) Sandy clay M It Bentonitic clay Sandy clay -1.7 Bentonitic clay -5.8 M

It

Pressure Moisture by weight in 2 kg./cm (%) 2 10 2 2 5

22 22 49 20 46

Amount of water in liquid phase (% of total moisture) Freezing under atmospheric Freezing under pressure added pressure

50.2 72.7 59.3 42.4 42.5

61.5 74.2 66.1 58.1 45.6

less than 0.001 mm may be attributable to the presence of a considerable amount of colloidal particles. The perceptible effect of the ice ratio during freezing is caused by the pressure under which the ground is subject to freezing. The experimental work of N.A. Tsytovich (1957) shows that even a slight pressure of 2 kg/cm2 results in more than 10 percent difference in the ice ratio as compared with the test when no pressure was applied during freezing (Table 2).

Permafrost Landscapes Permafrost areas generally possess distinctive landscape features, which range from microrelief elements such as patterned ground to larger features such as asymmetrical valleys, pingos, and large polygons, some of which are more than 100 ft. across. 47

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS The distinctive features of the permafrost landscape are the result of any one, or a combination of several, of the following essential factors: 1.

Low precipitation—generally less than 250 mm ( 10 in.) a year;

2.

Ineffective erosion due to the relative resistance of frozen ground during the spring thaw;

3. Active solifluction of surficial ground over the impervious frozen ground; 4.

Localized hydrostatic pressure of confined water during the winter freeze; and

5.

Melt of large masses of ground ice or the formation and growth of ground ice bodies, such as ice lenses and ice wedges.

The normal sculpturing of the surface features of the earth is seriously hindered by permafrost, which retards the headward erosion of streams in frozen ground. Tributary gullies, wherever they may be found, reach only a short distance towards the main drainage divide. The erosion of gullies and small valleys is also slowed down by the presence of snow, which melts slowly and remains in the shaded low areas for a long time, protecting the ground from active erosion by flowing water (Figure 20A). The broad drainage divides have a typical hydrologie network of numerous interconnected lakes of temporary existence. These lakes are only slightly incised into the earth's surface. The drainage in broad divide areas may be so poorly established that some lakes situated near the brow of a river valley drain in the opposite direction. Ultimately, such lakes through undercutting action of the stream may drain into the nearby river. The lakes occupy depressions either in the morainal relief or in those produced by an irregular series of frost mounds. Some lakes either completely or in part transform into swamps. Such a hydrographie network on a surface covered by water-absorbing moss and lichen, and with only drizzling rains, shows little or no evidence of erosion action. Farther to the north, where areas of ground without any vegetation are larger, the conditions for denudation are better. In general, active erosion only takes place along the exposed slopes of rivers and along the seacoast. The processes of denudation are rendered more complex by solifluction, which tends to level off relief features. The shapes of river valleys are markedly influenced by both permafrost and seasonally frozen ground. Erosion is relatively more intense in areas of repeated freezing and thawing, especially where thawed ground has an excessive amount of moisture. In the far north, for example, near latitude 60 °N, the valley profiles of many east-west-aligned streams show a decided asymmetry. On June 22, the north-facing slopes of about 15° receive the sun's rays at an angle of about 35°, whereas on the same day the angle of incidence of light on the south-facing side of the valley may be 60°. During winter, the north-facing (shadow) slopes do not receive any light, even during the noon hour. In the northern part of the Arctic (Figure 21 A), a typical valley in the mountainous region generally has a north-facing slope of about 15° in angle. It is covered by a thin layer of soil from 5 to 40 cm thick and generally has an open stand of small 48

FRO/EN IN TIM ir;: PERMAI ROST AND ENGINEERING PROBLEMS

Figure 20. Examples of fluvial erosion in permafrost terrain: (A) erosion of small gullies is effectively retarded by snowbanks that remain until late spring or early summer and the ground beneath the snow remains frozen, resisting erosion (photo courtesy of F.C. Erickson); (B) melting of ground ice (ice wedges) at the intersection of polygons ultimately produces the "beads" in a beaded stream; (C) "beaded" stream, a typical landscape feature of permafrost terrain. (Photo courtesy of F. C. Erickson).

49

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS scraggly larches and patches of moss. The soil is underlain by 2 to 3 m of ground ice. In the upper part of this layer are occasional dead roots of trees, clumps of moss and soil, and in the lower part small fragments of bedrock. The snow cover is generally thin, not exceeding several centimeters. The ground ice is regarded to be of infiltration-solifluctional origin, as explained by S.P. Kachurin (1946). During the summer the ice does not melt and only its upper layers creep or slide downward, as is evidenced by the curved trunks of trees and by the tongues of ice that overhang the slopes of steeply undercut stream banks. The opposite slope of the valley, facing the sun, is generally gentler. It is, on average, about 8° in angle. It is covered by sandy clay, commonly more than 20 m thick with inclusions of slabs of bedrock, fragments of tree trunks, stumps, and buried surface soils. These deposits on the south-facing slopes are in a state of flowage. In contrast to the north-facing slopes, the trees on the slopes facing the sun have a denser stand, containing growth of bushes, and the trunks of trees show even more pronounced curving due to the more active creep or flowage of the soil. In burned areas in which vegetation may have been completely destroyed, solifluctional processes may assume catastrophic proportions. The large quantity of solifluction material from the south-facing slope tends to push the stream against the steeper north-facing (shadow) slope, which generally terminates against the stream with a vertical slope, exposing bedrock (see Figure 21A). Divides in the permafrost area undergo a gradual shift to the north, as is evidenced by a few relics of former divides, which survive in the upper reaches of the gentler south-facing slope. In the southern part of the Arctic and Subarctic, as well as in the areas of intense seasonal frost, east-west oriented valleys tend to have steeper slopes facing south (Figure 2IB). This relationship is diametrically opposite from that found in the extreme northern areas. The shadow slope is gentle, generally swampy with a thick cover of sandy clay, having inclusions of slabs of bedrock. The thickness of sandy clay often exceeds 20 m. The surface is covered by a dense stand of small birches and conifers with apparent undergrowth of shrubs and grasses. The presence of soil creep is evidenced by curved tree stumps and widely distributed settling fractures of the creeping ground. The south-facing slope is steeper. The bedrock is blanketed by 1 to 2 m of debris from the weathering bedrock and capped by turf. Surface outcrops of bedrock are common. Little or no evidence is found of the process of creep or solifluction. Erosion takes place by normal surficial removal of material by rainwater. Vegetation consists of large trees, bushes, and a carpet of moss, commonly with no grass cover at all. The movement of surficial material from the north-facing shadow slope pushes the stream against the south-facing slope (see Figure 20B). These two types of asymmetric valleys have certain features in common. First, the gentler slope receives more moisture and has a longer period of spring and autumn freezing and thawing. These factors contribute to more active physical and chemical weathering. In the northern belt, the north-facing (shadow) slope does not thaw out at all, and the bedrock below the lower layer of ground ice does not suffer a wide range of changes in temperature. On the south-facing slope, on the contrary, 50

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 21. Profile of asymmetric valley: (A) northern part of the Arctic; (B) southern part of the Arctic and Subarctic (after Presnyakov 1955).

intermittent or sporadic freezing during summer nights is common and the moisture content (in liquid phase) is considerable. Second, in the southern belt the south-facing slope undergoes rapid drying, leaving little if any water to react with bedrock. The processes of sporadic freezing or thawing occur only during short periods of spring and autumn. On the other hand, the north-facing shadow slope remains moist almost to the end of autumn and sporadic freezing of surface ground takes place over a considerable period of time. In both cases the river channel shifts against the opposite, steeper slope. Thus, the gentle slope widens not only in the lower reaches where it pushes away the stream but also near the divide where it "eats" its way into the adjacent steeper slope of the neighbor stream. Distinctive streams, known as "beaded streams," develop in permafrost areas underlain by ice-wedge polygons. Water, which normally remains stagnant in the troughs between the polygons, flows along the polygon divides. This is caused by

51

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS a steepening of gradient either by headward erosion or by other causes. The flow of this water tends to thaw wider areas at the intersection of ice wedges, producing wide arcs or "beads" along the course of the stream (Figure 20B, C; see also Figure 23). Flood plains of large rivers, particularly near their mouths or deltas, deposit large amounts of silt during the spring high water level. These become cemented by frost action, ultimately causing the river to shift from one channel to another. Wide plains of the Yukon, Mackenzie, and other large rivers in Eurasia abound with ox-bow lakes, many of which are, in part or in their entirety, overgrown with peat bog. Many areas in the Arctic and Subarctic regions that are underlain by permafrost exhibit a spectacular variety of surface patterns. These range from stripes and step-like terraces on sloping surfaces, to the polygons, circles, and nets that occur dominantly on level or slightly sloping ground (Figure 22A-F). In the past, these ground patterns have been given a variety of different terms, all of which have been recently grouped by A.L. Washburn (1956) into five fundamental types: (1) circles, (2) nets, (3) polygons, (4) steps, and (5) stripes. Two kinds of patterns are recognized in each of these five types—sorted and non-sorted. Locally, one type of pattern grades into another. For example, stripes may gradually pass into polygons or nets, although abrupt changes from one pattern to another can also be observed. These patterns on the ground are outlined by a number of features. Some are delineated by distinct bands or a mosaic pattern of vegetation (Grigor'yev 1956), others may be outlined by concentration of stones and boulders, still others are marked by features of relief. Grooves may be arranged in a polygonal pattern with each unit or polygon, called a mesh, forming a slightly depressed area with a more or less distinct ridge bordering the groove. In other patterns, an individual mesh may form a more or less convex mound. Dimensions of individual polygons range from a few centimeters to several tens of meters. A characteristic of some polygons is their orthogonal pattern, somewhat resembling a checkerboard. S.V. Obruchev (1938) studied such polygons in the region of Chaunskaya Guba and observed that one system of fissures in such polygons is generally parallel to the nearby bank or edge of a river, valley, terrace, or water shoreline, and the other system of fissures is at right angle to the first. Such regularity of fissures is observed in areas of homogeneous alluvial or morainal deposits bordered on one or both sides by a straight boundary. This regularity of fissures is also observed where alluvial deposits are bordered by material of different composition, such as bedrock or alluvium of different lithology, or, again, a boundary with a body of water beneath which the permafrost table drops sharply downward. These conditions create a distinct boundary during the contraction and expansion of the ground, producing fissures that parallel such a boundary (Grigor'yev 1956, Lachenbruch 1960b). Hexagonal or non-orthogonal polygons may occur in association with tetragonal polygons. Gorodkov (1950) states that hexagonal polygons are formed, for the most part, in well drained areas, whereas tetragonal polygons predominate in swampy areas. It has been recently suggested that the nonorthogonal system of polygons with tri-radial intersections are the result of cooling of homogeneous, relatively non52

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS plastic material (Lachenbruch 1960b). The subject of patterned ground has been recently discussed in detail by C. Troll (1944; English translation 1958) and critically summarized by A.L. Washburn (1956). A more recent review of the earlier studies of patterned ground by S.P. Kachurin (1960) shows the shortcomings of the different schemes of classification and of the mode of origin of polygons. The earlier classifications were based dominantly on surface features and relief, with little or no consideration given to the internal structure of the ground. According to S.P. Kachurin (1960, p. 18) the basic conditions under which patterned ground forms are controlled by the texture of the material—whether it is homogeneous or heterogeneous, and the proximity of bedrock to the surface of the ground. These conditions determine whether sorted or non-sorted polygons result. There are numerous deviations from typical polygonal patterns, caused by local differences in the initial microrelief, hydrologie conditions, the amount of snowfall, erosion by wind, intensity of ground heaving, and other factors. In well drained coarse sand, which is relatively free of water, sand-wedge polygons form without ice wedges (Péwé 1959). Although patterned ground is common in cold-climate areas, similar and almost identical features are known to exist in temperate belts and even in arid warm regions either as relicts of periglacial condition or as a result of desiccation and crystallization of salt wedges (Hunt and Washburn 1960). A significant feature of the landscape in permafrost areas is the large number of isolated small and large lakes. These owe their origin to the melting of small or large masses of ground ice. Such lakes are generally referred to as either cave-in or thaw lakes (Figure 23A-C). As melt of a large ground ice lens progresses, overlying soil and turf topples over the bank. A cave-in lake may either drain away and dry up or may heal over by the spread of peat bog with the ultimate permanent freezing of water to form a large ground ice lens. Lakes of probable cave-in type are especially common along the Arctic Coastal Plain in both Asia and North America. In Alaska these lakes occupy from 25 to 80 percent of the area of the Coastal Plain (Black and Barksdale 1949). A peculiar feature of these lakes is that their longer axes are more or less uniformly oriented in the northwesterly direction (Figure 24). They range in size from small ponds of a few tens of feet across to large lakes of several miles in length. These lakes range in depth from 2 to 20 ft. and more. Black's studies show that the prevailing northeasterly winds tend, through wave action, to undermine the westerly shores of the lakes and thus obliterate the preexisting northwest orientation. But if their original orientation were the result of an original northwesterly wind direction then a significant climatic change must have taken place since their formation. As the Alaskan Coastal Plain is an area of geologically recent emergence, the original textural pattern of the terrain and microtopographic features may have had some effect on the orientation of the lakes. Melting of ground ice in a well drained site may produce depressions without any standing water or lake formation. Such depressions, because of their superficial similarity to karst depressions in limestone regions, are referred to as thermokarst (Figure 25 A). Another manifestation of thermokarst is shown in Figure 25B, where a polygonal network of ice wedges melted away, leaving the centers of polygons 53

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 22. Examples of the types of patterned ground that occur in permafrost terrain: (A) Air photo of stone stripes, northern Alaska (photo courtesy of U.S. Navy). (B) Ice-wedge polygons with raised edges and with secondary smaller polygons within the larger ones, Arctic Canada (photo courtesy of J.A. Pihlainen). (C) Raised-center polygons develop where water, which normally stands stagnant in the trenches, finds an outlet through a more or less well established drainage system. As more water is drained off from thawing ice wedges, the raised edges of the polygons gradually slough-off into the troughs (photo by S.W. Muller). (D) Air photo of large-scale ice-wedge polygons, Colville River delta, northern Alaska (photo courtesy of U.S. Navy). (E) Oblique air view of solifluction lobes or festoon terraces, Brooks Range, Alaska (photo by S. W. Muller). (F) The pattern of ice-wedge polygons is accentuated by different kinds of vegetation and by standing water in some of the depressed-center polygons (photo by S. W. Muller) (G) Stone rings (photo courtesy of T. L. Péwé). 54

FROZHN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

55

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 23. Cave-in lakes, near Northway, Alaska: (A) in winter; (B) in process of formation; (C) near end of the thaw-lake cycle (photos by S. W. Muller).

Figure 24. Air photo showing beaded stream and oriented thaw lakes along the Arctic Coastal Plain, northern Alaska (photo courtesy of U.S. Navy).

56

FROZEN IN TIM H: PERMAEROST AND ENGINEERING PROBLEMS

Figure 25. Thermokarst features: (A) a sinkhole produced by melt of ground ice; (B) residual mounds produced by the melt of ice wedges. Both photos are from near Fairbanks, Alaska (both photos courtesy of T. L. Péwé).

57

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS as mounds. Such mounds, as relicts of former (periglacial) permafrost with icewedge polygons, are not uncommon along the southern periphery of the present day permafrost area. Besides the residual mounds described above, the permafrost area abounds with mounds of positive growth above the present land surface. Among these are the pingos referred to earlier. Other types of mounds that are more common are frost blisters. Frost blisters (ice mounds) generally form on sloping surfaces where groundwater, confined between the permafrost and the overlying frozen active zone, develops sufficient hydrostatic pressure to bulge the overlying ground upward. Locally, the hydrostatic pressure may be sufficiently great to rupture the overlying crust of the ground and spill some of the supercooled water on the surface (see Figure 17).

Vegetation An intimate interaction exists between vegetation and permafrost, but much remains to be learned about the relationships between plants and the thermal regime of the soil in different physico-géographie environments. Particularly lacking are quantitative data for different parameters. The chief effect of vegetation on the thermal regime of the ground is that it provides an insulating blanket that impedes the warming (or thawing) of ground in the summer to a greater extent than it shields the ground from freezing during the winter. This is especially true of vegetative covers such as peat and moss. During the warm season, ice-saturated peat and moss obstruct warming of the underlying layers of soil because of the high specific heat of these materials, as well as the latent heat involved in melting ice and evaporating water. During the dry season, the dried-up surface layer of peat moss with its high insulating property protects the immediately underlying layers of soil from warming and drying. With progressive accumulation of peat-moss during successive summers, the soil becomes increasingly colder and tends to become swampy. During the winter the watersaturated moss freezes, losing its high heat insulating property. As a consequence, it offers little obstruction to freezing (loss of heat) from the underlying layers of soils. Thus, the balance of heat exchange between the ground and the atmosphere is on the negative side (see Figure 4). A vegetative ground cover also obstructs solar radiation, locally as much as 100-fold, retarding the warming (or thawing) of soil during the summer. Trees and bushes check the velocity of the wind and contribute to local accumulations of fluffy snow, which exerts a marked effect on the heat exchange between the ground and the atmosphere. Early winter snow reduces loss of heat from the soil, whereas late winter snow retards warming (or thawing) of the ground in spring and early summer (see Figure 5). The combined effect of peat, moss, snow, and vegetation on the thermal regime of the ground is diagrammatically shown in Figure 26. The greatest retardation in warming-up the soil is observed in the tundra (right-hand side, Figure 26) where the thickness of peat and moss is greatest. The soil warms the fastest where the ground cover of peat and moss is thinnest (left hand-side, Figure 26). Accordingly, in the

58

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 26. The combined effect of moss, peat, and snow on the distribution of roots and summer ground temperatures in I: forest, II: forest-tundra, and III: tundra, at latitudes 65°N, 68°N, and 70° N. (after Govorukhin 1957)

forest-tundra only those trees that possess a very shallow system of roots (middle sketch, Figure 26) survive. Even these trees perish in a moisture-saturated (frozen) cover of peat, as is the case on the tundra. Serving as an insulating blanket, the vegetative cover not only retards warming (or thawing) of frozen ground but also protects the ground surface from erosion. Where the vegetative cover is removed or destroyed by fire, the exposed permafrost will melt, producing a depressed area in the form of a funnel, gully, or lake. On the other hand, the spread of vegetation, over a lake or on land, may bring about the formation of permafrost where previously it did not exist. Such may be the case of a bog spreading over a cave-in or thermokarst lake. For example, the perennial aquatic grass, Tawny Arctophila, might establish itself near the shore of the lake. With years, the accumulation of dead parts of the plant makes the lake shallower. This forces the plant to move into deeper water. The area left behind is then occupied by the Buckbean Menyanthes, which, in turn, is succeeded by the horsetail Equisetum, followed by the sedge Carex aquatilis. With continued accumulation of organic matter, the lake turns into a grassy swamp and may subsequently become overgrown with trees and bushes. The accumulated vegetative material may raise the swamp to a sufficiently high level to dry it out. The plant debris now forms a layer of peat that gradually accelerates the negative heat exchange balance with ultimate formation of permafrost. The vegetation thus responsible for the formation of permafrost is then itself 59

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS subjected to a tolerance test under the newly created thermal conditions of the soil. The presence of permafrost prevents the soil from warming to the required optimum for the root system to function properly physiologically. Being impervious, permafrost causes accumulation of excessive moisture, which prevents proper aeration of the soil and reduces its nutrient content by slowing down the biochemical processes. The low temperature of soil produces what is known as physiologic drought, a condition that retards the absorption of moisture by the roots to such a degree that they are unable to provide the required amount of moisture to the living organs above the soil, and the plant perishes. Although this condition is regarded by some as one of the main factors responsible for the treeless condition of the tundra, V.P. Dadykin (1952) cites experimental studies that do not support the theory of physiological drought. The low temperature of the soil retards the growth of roots, both in length and in thickness, weakens their ability to branch, and prevents them from penetrating deeper into the soil. The low temperature of the soil slows down the synthesis of albumen, without which no living cell can exist. A vigorous growth of plants in cold, poorly aerated soils is inhibited by their inability to assimilate nutrients, particularly nitrogen. It has been shown however, that this difficulty can be overcome with perceptibly satisfactory results by feeding nitrogen to some plants by spraying their leaves, which are the organs of synthesis (Grigor'yev 1956). In permafrost areas, V.P. Dadykin (1952) distinguishes three types of native plants according to differences in their root penetration into the various thermal zones of the soil. The root system of the first type has expanded lateral roots that generally do not penetrate the soil beyond a depth of 30 to 35 cm. Most of the trees and bushes fall into this group. The second type includes plants whose roots reach to the permafrost table. The third type includes plants whose roots, even at the end of the vegetative period, extend into the frozen soil. Horsetail (Equisetum silvaticum), sedge (Carex globularis), and cloudberry (Rubus chamaemorus or "moroshka") have all been observed with root depths of 90 cm. Experimental work at the Institute of Merzlotovedeniya has shown that roots remaining in the frozen soil throughout their vegetative period are not physiologically at rest but are functioning in the exchange of substances and undergo mitosis, which constitutes plant growth (Grigor'yeva 1950). Under an arctic climate, some plants effectively adapt to the permafrost environment by developing shallow, horizontal roots with positive thermotropism, that is, an ability to grow in the direction where the soil is warmer. Some trees and shrubs have developed the ability to send out secondary roots to replace dead ones engulfed in unfavorable lower soil layers. Among common trees, the pine is the most sensitive to the proximity of permafrost; the least sensitive or the most tolerant is the larch. Larch, with its horizontal, shallow system of roots, is well adapted to withstand the presence of permafrost at shallow depth (see Figure 25). But larch does not extend far south beyond the area of permafrost, where it is replaced by shade-tolerant evergreen trees. The southern limit of solid stands of larch may, thus, be used as an approximate indicator of the southern limit of permafrost; isolated stands of larch usually indicate sporadic occurrences of permafrost. 60

FROZHN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS In North America the genus Larix occurs in commercial stands in British Columbia, Washington, and Idaho (Professor Ira Wiggins, oral communication). It does not appear to be confined to permafrost regions. Even Larix laricina, the larch of arctic and subarctic regions, ranges south to northern Indiana, Ohio, Pennsylvania, and the New England states. Spruce, too, has a shallow, horizontal system of roots, but it is more sensitive to the temperature of the ground than larch and does well only where permafrost is at some depth below the ground, as along streams and in sheltered areas on southfacing slopes. Pine species usually indicate a well drained (sandy) active zone and a considerable depth to permafrost. Pines extend well beyond the southern boundary of permafrost. To the north of the southern permafrost boundary, they are gradually replaced by larch and survive only in most favorable sandy areas along major streams. Pines do not tolerate cold, clayey soils, and a thin active zone. Alders and willows occur in permafrost areas along the floodplains of streams and along lakeshores. They usually indicate the presence of a high water table and a considerable depth to permafrost, if any is present (Figure 27). It has been shown that in the area of sporadic occurrence of permafrost, its local presence was generally indicated by sphagnum swamps, sparse stands of terees in sphagnum swamps, and wooded areas with ground cover of sphagnum moss. Many other plants may be used as diagnostic indicators for either the presence or absence of permafrost, or the relative proximity of permafrost to the ground surface. However, the criteria furnished by plants must be evaluated with proper allowance for other factors that may explain an occurrence of similar plant associations under two, more or less different, environments. In general, as stated by A.A. Grigor'yev (1956), the short duration of the vegetative period in the north is the result of low mean monthly air temperatures, and large amplitudes of extreme temperatures. Therefore, the vegetative cover must be prepared at any moment during the summer to cope with unseasonal frost events. These can be especially frequent and severe in the beginning and end of the vegetative period. In addition, high temperatures at the peak of summer may be experienced. Almost every year in the Subarctic, there is a short period of hot days when the air's relative humidity is low and evaporation rises sharply, causing drying not only of the humus-peat layer but also of the uppermost part of the mineral soil. On the other hand, the low summer air temperatures in the Subarctic are accompanied by high values of monthly net radiation (June to August) and total radiation (from May on). When combined with excess diffused ultraviolet radiation, these conditions may stimulate protective reactions in certain plants. Finally, the winter rest of vegetation in the Subarctic takes place under conditions of uneven snow cover distribution. The latter is easily blown off by wind in the treeless tundra from one element of relief and deposited on others. At the end of the cold period, when radiation is already high but the soil is still frozen, those surface organs of wintering plants that are not protected by snow are exposed to the danger of desiccation. Furthermore, the slowly melting snowdrifts shorten the vegetative period of plants buried beneath them. All these complex conditions are, in general, unfavorable and occasionally 61

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 27. Distribution of permafrost in relation to relief and vegetation in southern Transbaykalia (after Tolstikhin 1941).

destructive; they can be reduced to four categories of phenomena to which the vegetation of the Subarctic has to adapt: 1.

A relatively short period during which plants are fed and supplied with warmth;

2.

Low, freezing temperatures of the winter and at different times during the vegetative period;

3.

Periods of insufficient moisture for surface organs during the warm, as well as the cold, period of the year; and

4.

An excessive amount of ultraviolet radiation.

It is not surprising that only a limited number of plant species are able to adapt to such complex, difficult external conditions. Even such a favorable condition as continuous daylight excludes the possibility of survival of those plants that require a considerable number of dark hours for their development. The least demanding vegetative forms, such as mosses and lichens, which are devoid of root systems, are easily adapted to such conditions. For example, Cladonia develops intensive life activity when it is warmed to 5°C and is capable of enduring desiccation for up to three weeks without any ill effects. It is true that, in such periods, the tips of the plant break off, but this does not cause any harm to the plant and stimulates the growth of side branches when the plant is again moistened. Broken-off fragments of lichen are scattered by the wind, occupy new places and there re-establish themselves, thus facilitating the distribution of lichens. Because of their wide tolerance, mosses and large lichens have a varied floristic composition in the Subarctic. In the East European sector, for example, there are about 500 species. It is a different matter with the more demanding representatives of vascular plants. There are a relatively limited number of these represented in the Subarctic. This number rapidly decreases as one progresses northward. According to Andreyev 62

h«)/EN IN TIMI-: PERMAFROST AND ENGINEERING PROBLEMS (1954), in the East European sector, including the forest tundra, there are about 700 species. Endemic forms, restricted to narrow habitats, are not very common in the tundra belt. Most vascular plants are widely distributed in the Subarctic, many forms being circumpolar. Vascular plants typical of the East European Subarctic are Cyperaceae (sedges), grasses, Ranunculaceae, Cruciferae, Rosaceae, poppies (polar), Saxifragaceae, Leguminosae (Astragalus], Compositae, Pyrolaceae, and catchfly (Silène) of the Caryophylloceae. The bushes widely distributed in this belt are crowberry (Empetrum), Vaccinium, bearberry (Arctous alpina), bog rosemary (Andromeda), and leather leaf (Chamaedaphne ). Among the larger bushes, the dominant role is played by the dwarf birch, various willows (Salix), and Labrador tea (Ledurri). All the plants referred to above have adapted to the four categories of unfavorable external conditions mentioned. Of these conditions, subzero temperature and a temporary shortage of moisture have much in common in their effect upon plants. The wilting of a plant due to lack of moisture and the formation of ice crystals involves the removal of water from surrounding materials, be they soil or plant. Thus, there is much in common between frost and drought. The unfavorable conditions for plant nutrition in the Subarctic mean that plants produce only a limited amount of live organic matter. This increases from north to south as external conditions improve. As a result, subarctic plants are small, their rate of growth and fruiting is slow, and many higher plants are not capable of producing ripe seeds every year. In most of the berry bushes, as well as in Rubus, extensive annual ripening of berries takes place, as a rule, only along the southern border of the belt. Dwarf birch, Ledum, and other plants along the northern border of their distribution lose the ability of sexual reproduction and transform entirely into vegetative multiplication. Other plants (Dryads) react to the adverse conditions by lengthening their individual life span, as well as by annually generating shoots for seed propagation, expending a minimum amount of organic substance on these shoots. As soon as seeds are ripe, the increased velocity of wind in the tundra belt provides excellent conditions for their dispersal, not only during the summer, but also during the winter. Even seeds that lack the special structures necessary for transport (wings, parachutes, and such) are carried considerable distances during the winter. In the Central Siberian tundra, snowdrifts on the lee side of slopes contain large quantities of seeds and fruits of many plants, fragments of various lichens and mosses, and various remains of vascular plants. In general, it is characteristic for the Subarctic that seeds ripen only during the warmer years, when unripened fruit is able to survive the winter and ripen the following summer, or while still under the snow, as is observed in certain plants. Thus, not only are all bushes and shrubs perennial but almost all herbaceous plants are also perennial in the Subarctic. On the tundra, perennial vascular plants may attain a considerable age. For example, dwarf birch, Empetrum and the alpine Arctostaphylos can live 75 to 80 years and occasionally to 100 years. Sieversia glacialis, of the Rosaceae family, is characteristic of the northern Siberian tundra and occasionally may reach the age of 63

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS 150 years. In general there is a tendency for the life span of tundra and alpine plants to increase with a progressive increase in severity of surrounding environmental conditions. There is the possibility that some plants continue to develop under the snow cover. With a thickness of snow of 2 to 3 cm, up to 50 percent of the sun's rays may pass through. It is well known that photosynthesis is possible at temperatures as low as -5°C. The warm layer of air near the ground surface in the Subarctic is the reason the height of the stems of most blooming plants does not exceed 8 to 10 cm above the ground. Also, the greater thickness of snow in the Subarctic has a negative effect on the development of plants. Thick snow melts late during the spring, thus, shortening the vegetative season. Finally, the abrasive and polishing action of the wind increases with a lowering of temperature. For example, the hardness of snow at -15°C varies between the hardness of gypsum and calcite, at -30°C between that of calcite and fluorite. At -44°C it is equal to the hardness of fluorite, and at -50°C to that of orthoclase. According to A.A. Grigor'yev (1956), the factors mentioned above materially affect the details of configuration of the geobotanical zones in the Eurasian Subarctic. The main pattern is determined by the combination of climatic conditions expressed chiefly in the radiation balance of the earth's surface, monthly air and ground temperatures, the amount and regime of precipitation, and the ratio of heat radiation to moisture. In areas protected from northern winds and more favorably situated with respect to sunlight, the zonal boundaries tend to deviate northward. The same effect is also shown where drainage conditions allow plants to reach farther north than would otherwise be expected. The large extent of the Subarctic allows subdivision into several geobotanical zones of different order. The northern zone of the Subarctic coincides with the Arctic tundra, where the flora of higher plants consists chiefly of grasses, sedges, and some bushes. The prevalence of grasses is a distinctive feature of this plant community. These plants are restricted to polygonal tundra, where vegetation is concentrated along the troughs of frost fissures and along the drainage between the polygons. In these places plants are protected from the wind, covered by snow in winter, and are adequately drained during the summer. Thus in this zone, plants are distributed in narrow bands separated from each other by bare ground. These bands, or stripes, of vegetation consist of various fruiticose lichens (Cladonia, Cetraria, and such), folióse lichens, and green mosses, which form a variegated carpet in which, here and there, are found higher plants. Among the higher plants are trailing forms of willow of small dimensions, not higher than 20 cm, and tolerant grasses such as Alopecurus alpinus, several species of sedges, Luzula confusa, Oxyria digyna, Polygonum viviparum, occasional Saxífraga, Rununculus, the yellow or white Polar poppy, some crucifers, Artemisia borealis, and others. The Arctic tundra is distinguished from the Arctic semi desert by the fact that the vegetation forms continuous, through narrow, bands or stripes; whereas in the Arctic semi desert, the plants are scattered singly only on well drained divides and rarely 64

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS exceed 10 cm in height. The Southern Zone of the Tundra is distinct from the northern zone by the presence of upright bush vegetation. These bushes decrease in height progressively farther to the north and areas of bare ground become progressively smaller. There is a successive change in tundra communities that permits subdivision of this zone into (1) a northern subzone of moss and lichen tundra, and (2) a southern subzone, known as bushy tundra. The northern subzone is characterized by moss-tundra with some sedges and Dryads with their large white flowers. Polygonal, Actinium vitis-idaea, V. uliginosum, Valeriana capitata, Stellaria longipes, Saxífraga hirculus, Ranunculus airicomus, Pedicularis versicolor, Cardamine pratensis, and other forms are also found here. Bushes, such as willows and dwarf birch, are widespread, occupying 20 to 30 percent of the area. The dwarf birch reach heights of only 15 to 20 cm and are found only on the higher and better drained slopes. In depressions where snow accumulates during winter, they form small groves. Willow bushes attain heights of 50 to 60 cm and occasionally even 1 m. Swampy divides and depressions are occupied by sedges, mixed with cotton grass. Locally, on well drained sands, there is lichen tundra, but the area is insignificant. Narrow bands of willow stretch along the river valleys; these trees, which reach a height of 3 m, consist of species different to those occurring in other parts of the tundra. The chief characteristic of the southern subzone, which extends over a wide area in Bol'shezlmel'lskaya tundra, is the widespread development of bushes, which occupy almost all areas except swamps. Because of this, this area retains an adequate amount of snow in the winter months. Approaching the northern subzone of the lichen-moss tundra, the bushes of the moss-tundra appear to be limited to places sheltered from strong winds and where snow accumulates. The most typical and widely distributed plant of the southern subzone is the dwarf birch. This is found in poorly drained places with excessive moisture. In western Siberia, it is represented by the species Betula nana. In eastern Siberia, this species is joined by the Siberian species, Betula exilis, as well as by Betula sukatchevii. Both species are distinguished from Betula nana by the development of glands along the bark of the branches and on the leaves. These dwarf birches gradually increase in size to the south but in general do not exceed 0.5-1.0 m in height. The occurrence of birch is closely connected with the presence of the small mound microrelief typical for the southern subzone of the southern Siberian Subarctic. Establishing itself between the mounds, the dwarf birch finds a location well protected by snow during the winter. Along with the dwarf birch, the bushy tundra also contains heather and willow thickets, which may be 2 to 4 m high. The latter usually occur along the bottoms of gullies or along streams. Another distinctive feature of the southern subzone is the development of Sphagnum in the moss tundra, along with green mosses. The preceding discussion, according to A.A. Grigor'yev (1956), serves as a basis for recognizing similar geographic areas in North America. This is borne out by the presence of many identical and similar plants recorded from the Arctic of North America by D.M. Hopkins and R.S. Sigafoos (1950), M.E. Britton (1957), and others. While a similar division of the North American Subarctic into the two zones

65

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS is visualized by Grigor'yev, he is aware that there are also some local peculiarities of conditions on the North American continent. For example, the greater part of the Canadian tundra is situated in Precambrian shield bedrock where unconsolidated sediments are limited or entirely absent. This tundra, developed on rocky terrain, has a distinctive morphology and vegetation. Also, the tundra of Alaska is markedly modified by the close proximity of mountain ranges and some extends to the Beaufort Sea shore.

Physical Properties of Permafrost Understanding the physico-mechanical properties of frozen ground is the first step in the planning and execution of engineering projects. The physical properties of frozen ground depend on its composition, texture, content of ice (ice ratio), and temperature. Well indurated bedrock, free of ice-filled joints, shows so little difference in its mechanical properties when it passes from a frozen to a thawed state that it may be entirely left out of consideration. On the other hand, unconsolidated surficial deposits (gravel, sand, silt, and clay) undergo marked changes in their physical characteristics during the processes of freezing and thawing. During freezing, fine-textured ground (soil) crumbles due to the formation of ice crystals when the soil moisture passes from the liquid to the solid state. During slow freezing, fewer but larger crystals are formed than when ground is subjected to rapid freezing. The latter produces a larger number of smaller crystals. During freezing, frost-susceptible ground may heave with considerable upward force, sometimes causing irreparable damage to pavements, buildings, and other engineered works. By contrast, clean gravel and sand are relatively non-frost-susceptible and heave only slightly when saturated with water. The freezing of sands shows that, where a free supply of groundwater is available, the volume of sand upon freezing remains practically unchanged. In such cases, the pressure exerted during the growth of ice crystals spreads quickly to the adjacent sand and excess water is pushed aside, resulting in a decrease in the over-all moisture content of frozen sand. Fine-grained aggregates such as silt and clay, on the other hand, are strongly frost susceptible and should be avoided when building any structure. As has been shown by Taber's experiments (see Figure 12), the heaving of fine-textured materials is due primarily to the redistribution of moisture and the formation of ice lenses. The redistribution of moisture in test samples of sand, silt, and clay during freezing and the accompanying heaving has been also demonstrated by I.S. Vologdina (1936) (Figure 28) and others. Whereas clean gravel and sand generally do not heave, a small amount of silt or clay, accidentally or by design, admixed to these materials will radically change their characteristics and will make them susceptible to heaving. Experiments have shown that aggregates containing 3 percent or more of particles of 0.02 mm make ground frost susceptible. To avoid this "pollution," measures should be taken to protect clean, non-frost-susceptible backfill from an inflow of muddy water by placing appropriate coverings or screens of impervious material. Strong heaving usually occurs under open-system conditions—where a considerable amount of water is available below or adjacent to the freezing ground—

66

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 28. Swelling of ground on freezing from the top (after Vologdina 1936).

67

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS rather than under a closed system in which no additional water is available. As downward freezing progresses, water is drawn through the capillaries by the frozen ground and added to any already-formed ice. The magnitude of heave is directly dependent on the supply of water. The mechanics of this capillary attraction of water is not entirely understood. Some workers believe that it is dominantly, if not entirely, due to the thermo-electric osmosis. Others bring into play the suction effect of the pore space upon condensation of water vapor; still others explain it by the mechanism of crystallization. The volume of papers published in connection with thermal moisture migration problems and frost heaving is large. Perhaps the earliest recognition of thermoosmotic phenomena was by H.E. Patten (1909), who described them as an annoyance in a paper on soil heat transfer. But H.P. Winterkorn (1947) reports that it was G.J. Bouyoucos (1915) who made the first detailed studies on thermal moisture migration. Bouyoucos found the following: 1.

Moisture moves from locations of high temperatures to locations of low temperatures.

2.

There exists for every soil an optimum moisture content at which a maximum amount of moisture is moved under a certain temperature gradient.

3.

This optimum moisture content falls in the vicinity of the plastic limit.

4.

Moisture movement can, in part, be ascribed to vapor pressure movement.

5. Bouyoucos postulated that this occurred because of a variation in water affinity (or capillary potential) with variation in soil temperature. Stephen Taber (1918; 1929; 1943b) made what are probably the most important contributions to the study of thermo-osmosis. His experimental work with freezing soils showed that moisture migration depends on the soil type, with silts and clays being soils most subject to heaving. In addition, he proposed that moisture movement took place in the moisture films surrounding the soil particles, rather than via the vapor pressure movement proposed by W.O. Smith (1939) or the capillary potential differences proposed by Bouyoucos. In Russia, the work of A.E. Lebedev and initially reported by N.A. Tsytovich (1958) showed that water moves under the influence of molecular forces from thicker to thinner films. This agrees with the work of both Taber and G. Beskow (1935). As a result of World War II and the post-war highway construction boom, interest in thermo-osmotic phenomena greatly increased in the western hemisphere. The studies of A.R. Jumikis (1954; 1955a; 1955b; 1957a; 1957b; 1958) and E.S. Penner (1956; 1957a; 1958; 1959) are worthy of note because of their fundamental nature. The objective in studies of moisture migration is to determine what soils will be most susceptible to frost heaving. As of this time, the determination of a frost-susceptible soil is more qualitative than it is quantitative. For example, S. Taber (1930a; 1930b) suggested that when the particle size of a soil is less than 0.07 mm, ice lens can occur. A. Casagrande (1932) proposed that, for open systems, poorly sorted soils could be expected to heave if more than 3 percent of the grains were smaller than 0.02 mm. For well sorted materials, he suggested that, if more than 10 68

FROZEN IN TIME: PERMAFROST ANE) ENGINEERING PROBLEMS percent of the grains are less than 0.02 mm in size, the soil would be frost susceptible. Subsequently, Beskow (1935) offered the height of capillary rise as the frost criteria. He showed that, for a capillary rise of less than 1.0 m, there would be no heaving. For poorly compacted slope material, when the rise is from 1.0 to 1.5 m, and for highly compacted soils when the rise is from 1.25 to 4 m, the soil may heave. According to Beskow, loosely compacted soils with a capillary rise of 2 m, or highly compacted soils with a capillary rise of 3 m, can always be expected to freeze and heave. A basic fact in the study of freezing and thawing of water is that ice is a better conductor of heat than liquid water. This is because the interference of hydrogen bonding breakage is less in ice than it is in water (Low and Lovell 1959). Therefore, when a frozen soil is subject to a temperature increase in the spring, the rate of heat inflow into the ground is slower than the rate of heat outflow during the freezing period of the autumn or winter (Theis,1952). Before considering the basic mechanism of moisture migration, several other comments concerning frost heaving and moisture movement are necessary. First, before ice can form in soils, the temperature in the ground must drop below 0°C. However, in most frozen soils there exists a certain portion of pore water that is unfrozen (Linell and Kaplar 1959; Tsytovich 1958). The amount of unfrozen water varies from near 0 percent for coarse sands to 60 percent for fat clays. The unfrozen water exists because of the negative electrical charges and cation concentration in the soil (Grim 1952,1959; Linell and Kaplar 1959; Low and Lovell 1959; Tsytovich 1958). Second, a characteristic of freezing soils is that ice lenses grow perpendicular to the direction of heat flow. For most ice lenses, this will be parallel to the ground surface (Penner 1958). The ice layer thickness depends on the rate of cooling, the ion concentration, and pressure conditions. A.R. Jumikis (1955a; 1955b) noted that the ice lens will be thin in quickly frozen soils. On the other hand, N.A. Tsytovich (1957a; 1957b; 1958; 1961) observed that ice inclusions in soil will form different structures depending on the rate of cooling. Third, E. Penner (1958) observed that, in a closed system, a saturated non-compressible soil will heave because of the volumetric expansion of soil water upon freezing, the movement of water, and its expansion at the freezing surface. For compressible soils in a closed system, the volume expansion will be limited to the 9 percent water-to-ice volume increase because of consolidation of the soil. Soil between the ice lenses will be relatively dry in comparison to adjacent unfrozen soil. Fourth, the rate and amount of freezing is greatly influenced by soil grain size. Penner (1957), using blended lab samples of clay, silt, and sand, essentially confirmed the earlier work of S. Taber (1930a; 1930b) and I.S. Vologdina (1936) (see Figure 28). Fifth, when a soil system freezes, pore pressures become negative. This needs explanation before a valid frost heaving hypothesis can be obtained (Jumikis 1954; Taber 1943; Tsytovich 1957; Winterkorn 1947). The rate at which this socalled "suction force" develops is affected by moisture content, temperature, rate of cooling, and permeability (Linell and Kaplar 1959; Penner 1959). Definite evidence of negative pore pressure is illustrated by the upward flow of water during frost heaving. For closed systems the rate of negative pore pressure increase is initially high but drops sharply as more moisture is frozen.

69

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Finally, whenever vertical displacement of a freezing soil is prevented, considerable pressure builds up along the ice front (Gold 1957, Penner 1959). This pressure is transmitted from the frozen to unfrozen soil through a mobile layer, which has at least quasi-liquid properties because of the growth phenomena (Gold 1957). E. Penner (1959) has shown that this pressure can be neutralized by application of negative pore pressures on the order of twice the value of heaving pressure. He also showed that the amount of negative pore pressure necessary to stop or prevent ice lens growth, and corresponding heave of the soil, increases as the density of the soil increases. The exact mechanisms of frost heaving are still not understood. The recent literature is filled with tentative theories of moisture migration that appear reasonable for the particular soil or porous media in question (Gold 1957; Grim 1952 1959; Jumikis 1954, 1955a; Low and Lovell 1959, Martin 1959, Penner 1959, Winterkorn 1958). The suction theory advocated originally by S. Taber (1929) seems to be the most valid for silts and clays. The study of film and suction theories has become quite intensive in the past few years. Notable contributions on the topic have been made by A.R. Jumikis (1954, 1955a), E. Penner (1956, 1957a, 1958, 1959), L. Gold (1957), K.A. Linell and C.W. Kaplar (1959), and P.P. Low and C.W. Lovell (1959). These workers have made considerable progress in explaining Taber's theory, but experimental limitations have prevented complete understanding and, therefore, accurate, scientific in situ applications of thermo-osmotic knowledge. There seems to be fairly general agreement that moisture migration occurs through water film movements (Gold 1957, Jumikis 1955a, Keinonen 1961, Penner 1959, Tsytovich 1961); however, a number of questions arise: What begins the moisture migration? Why does the ice segregate in silts and clays but not in sands? Why is there unfrozen water in so-called "frozen soils"? Why does silt and clay experience volume increases of more than the 9 percent that can be attributed to water phase change increase? Why don't sands heave? The answers to these questions probably lie in the physical and chemical properties of soils and soil water. The following Russian observations reported by N.A. Tsytovich (1958) are probably applicable in most permafrost regions: Observations in nature and of special laboratory experiments show that thick intercalations and lenses of ice form in freezing ground if the frost boundary remains stationary for a long time at a certain level, as for example, in thaw weather during the cold seas on, or during the oscillation of the freezing boundary in a certain portion of the ground and in the presence of outside supply of water. According to Tsytovich, during rapid freezing of unconsolidated sediments moisture does not have time to move to the frost line. Under very low freezing temperatures, the intercalations are replaced by separate ice crystals, which cement the mineral particles. When these ice crystals do not alter the void space size and no particle reorientation occurs, the term ice cement is applied to the ice constituting these minute inclusions. This is distinguished from the ice that composes considerably larger inclusions, called ice inclusions or segregated ice. When only ice cement forms the ground texture, it is termed massive. These soils 70

FRO/EN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS are characterized in the frozen state by considerable strength and by retention of their strength properties upon thawing. A layered texture occurs where freezing is from only one direction under open-system conditions. Ice layers form because of moisture redistribution. The strength of such ground depends upon the extent and distribution of the ice lenses. Upon thawing, these soils lose much of their pre-freezing strength. A honeycomb or reticulate texture is formed when there is a systematic inflow of additional water, predominantly under conditions of freezing from more than one direction. The properties of frozen ground having a honeycombed texture are close to those of ground with a layered texture, but, after thawing, their strength properties do not deteriorate as much as in frozen ground having a layered structure. Tsytovich (1958) goes on to note that "the formation of inclusions, intercalations, and lenses of ice in freezing ground is the main reason for unequal volume expansion of ground in the process of freezing." Furthermore, Russians have found that even in open-system conditions the volume increase in sands upon the freezing of a volume of water equal to the volume of pore spaces in the sands is 3 percent. They account for this discrepancy as being made possible by the lateral squeezing-out of excess water. Thus, Tsytovich (1958) also says, "When sand is under hydrostatic pressure, the sand heaves because the volume of the water increase fills the pores formed by freezing under hydrostatic pressure (that is, cavities, fissures, and others) and in which the water froze later" The need for further fundamental research in thermo-osmotic phenomena is obvious. S. Taber's original theory (Taber 1929) seems correct but must be modified to account for the factors found by laboratory experiments and verified by field studies. In fact, it is difficult to see how safe, economical cold-climate engineering design can be achieved without extensive extended field studies of the type now being made in the USSR. Whatever the mechanism of migration may be, the redistribution of moisture during ground freezing, even in already-frozen fine-textured soil, is an established fact. In the larger capillary voids water freezes at the usual temperatures, but in very fine capillaries it may not turn into ice at temperatures as low as -17°C and even down to -78°C. Thus, heavy clays with very fine capillaries, while appearing to be frozen at a few degrees below 0°C, are actually only partly frozen and still contain an appreciable proportion of water in liquid state (see Figure 19). Currently, the use of chemical additives to minimize or eliminate frost heaving in fine aggregates is being investigated. Experiments with many different kinds of ground and different chemicals show that the most effective and economical dispersing agents are the salts of polyvalent cations of ferric chloride (FeCl3). Field tests show that sodium tetraphosphate effectively improves the ground and remains effective after a second cycle of freezing and thawing (Lambs 1956; Not in references or Bibliography). Treatment of heaving (frost-acting) soils with calcium chloride and sodium chloride also has been practiced with beneficial results. Test results show that 0.5 to 3 percent (depending on type of soil) of either of these chemicals prevents heaving. They do this by preventing freezing down to -23°C. However, test results show that these chemicals dissipate rapidly in soil moisture, and their strength is considerably weakened within a short time by leaching processes.

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FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Figure 29. Supercooling of water in ground of different texture (after Bozhenova 1955)

The beginning of freezing of ground is generally preceded by supercooling of the interstitial water, after which there is a sudden jump back to about 0°C. The temperature then remains constant for a certain period of time, which is known as the zero curtain—an interval during which chilling of water is temporarily compensated by latent heat of fusion. This is followed by the crystallization of ice and a gradual drop of temperature (Figure 29). The length of time that the water remains supercooled is directly related to the intensity of cooling, as shown in Table 3. With a coolant of -2.9°C, the supercooled condition lasts between seven and eight days, but with the coolant of -11.1 °C it lasts only 5 to 10 minutes. This relationship may account for the fact that, in nature, thicker ice lenses are formed in the ground during slow freezing, when the thermal gradient between the air and the ground is not great. A sudden freeze with very low air temperatures generally results in small, though more numerous, ice crystals. Under this latter condition, not enough time is allowed for the first-formed ice nuclei to draw liquid water from below. If the moisture content does not exceed critical moisture, little, if any, heaving will occur (critical moisture content is defined as the maximum amount of interstitial water that, when converted into ice, will not exceed the available pore space of the ground). 72

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS

Table 3: Supercooling of Water in Relation to Intensity of Cooling Temperature of Supercooling inC° Temperature of Coolant in C° -2.9 -3.9 -6.5 -11.1

In Interstices of Sand -2.9 -3.6 -3.2 from -0.2 to -1.9

In Large Vessel -2.9 -3.9 -6.5 -3.8

Temperature of Supercooled Condition of Water In Interstices of Sand about 2 hours 10- 15 min.

In Large Vessel 7-8 days 5 days 6 days 5- 10 minutes

Source: Bozhenova 1957.

In other experiments, it has been shown by A.P. Bozhenova (1957) that the pressure applied to moist ground tends to lower the temperature at which water begins to crystallize into ice. The decrease of moisture content also tends to lower the temperature of crystallization (Table 4). It has been established that the damaging effect of frost heaving on buildings and roads is primarily due to the formation of segregated ice lenses. Terrain of uniform composition and moisture content over a considerable area will heave uniformly and is unlikely to damage structures as seriously as will terrain whose frost susceptibility varies markedly from place to place. Unfortunately, this condition of heterogeneity of ground composition is not uncommon in the Arctic, where much of the terrain is veneered with glacial deposits of notoriously inhomogeneous character. The thickness of the active zone also affects the relative magnitude of frost heaving. Where the active zone is relatively thin as, for example, along the Arctic Coast, the ground heaves very little. In contrast, where the active zone is thick, considerable heave may occur. In the latter, the ice nuclei that form lenses during the early stages of freezing have access to a variable amount of water in the underlying, still unfrozen, part of the active zone. Differential heave may also be brought about by differences in heat conductivity of various components of the ground at different temperatures. For example, frozen clay with 40 percent moisture has higher heat conductivity than clay with only 20 percent moisture. Also, frozen clays are better heat conductors than sands with the same moisture content. Both have much higher coefficients of heat conductivity when frozen than when thawed (see Figure 30). Each of these materials, in turn, shows minor variations with temperature, both in frozen and in thawed states. An illustration of differential heave is provided by rocks and boulders resting within the near-surface ground. The materials beneath the boulder will freeze more rapidly than the adjacent ground beneath the surrounding turf and soil. An ice lens will form directly below the boulder at the expense of the moisture in the surrounding ground. The continued growth of this ice lens pushes the boulder upward, ultimately bringing it up to the surface of the ground. This is a familiar observation of many farmers in cool temperate climates whose arable fields have to be periodically cleaned of these "growing" stones. A similar process takes place where fence posts 73

FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Table 4: Effect of Moisture Content and Pressure on the Temperature of Beginning of Freezing of Ground

Type of Ground Specific Gravity Pressure kg./cm* Sand

Sand clay

Clay

1.65

-

1.90 1.94 2.12 2.18

0.5 1.0 10.0 65.0 1.0 10.0 40.0

-

Moisture in % by Weight 18.0* 7.0 1.6 36.0* 32.8 28.5 19.4 13.1 75.0* 54.5 41.6

Temperature at the Beginning of Freezing 0.00 -0.00 -0.31 -0.05 -0.10 -0.25 -0.84 -1.70 -0.80 -1.49 -3.58

Source: Bozhenova 1957 * Moisture at or close to saturation point.

Figure 30. Diagram illustrating heat conductivity of clay, sand, and water at different temperatures (after Evdokimov-Rokotovsky 1932).

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Figure 31. Diagram illustrating how annual ground temperature isotherms are affected by the shadow of an east-west fence. and telephone poles are uprooted from the ground. The four tables reproduced here from N.A. Tsytovich and M.I. Sumgin (1937) (Tables 5, 6, 7, and 8) provide some idea of the extreme variability of mechanical properties of different frozen ground materials and their dependence on temperature and moisture content. Keep in mind that the ground aggregates subjected to repeated freezing and thawing usually have lower compressive strength than comparable aggregates that were frozen only once. Significant changes in the physical properties of ground take place during thawing. The melting of ice weakens or destroys the bond between aggregate particles and markedly reduces the bearing strength of the ground. The moisture released from the melting ice moves downward by the force of gravity and concentrates directly above the still frozen impervious ground, thereby, dilating the aggregate to the extent that it may become a fluid and flow. This condition accounts for solifluction and landslides, which are common phenomena on sloping surfaces in permafrost areas. The loss of bearing strength in thawed ground composed of fine aggregates causes damage to buildings by settling. This damage is attributable chiefly to the differential thawing and settling of the ground. Other conditions being equal, even a very light structure tends to settle differentially on the south-facing side, where normal solar radiation plus reflection from the wall of the building causes thaw to a greater depth compared with the shaded north side. A simple board fence, running east and west, can produce a perceptible difference in ground temperature on the two sides (Figure 31). In the past, it has been thought that during the winter Arctic soils remain in an anabiotic state and that the permanently frozen ground prepresents a zone of chemical inactivity. These old beliefs were based on the general chemical concept of the effect of low temperatures on chemical reactions and on the belief that the water in the frozen ground was only in a solid phase. Because recent investigations have shown that water in the liquid phase may be present in frozen ground, it became apparent that such physico-chemical processes as oxidation, reduction, exchange of cations, coagulation, peptization, and other reactions may take place in the ground at subzero temperatures (Nersesova and Tyutyunov 1957). It has also been established that the subzero temperature not only makes the chemical reaction possible but, owing to phase change, can substantially increase the intensity and speed of physico-chemical processes.

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FROZEN IN TIME: PERMAFROST AND ENGINEERING PROBLEMS Table 5: Compressive Strength of Frozen Ground at Temperatures from -0.3°C to 2°C Ultimate Moisture Compressive Temperature (ice) in Strength in Ground Type inC° % kg/cm2 Sand with rubble (Grains: >lmm = 85%) -1.4 15 27 -0.8 Sand (Grains: >lmm = 80%) 18 28 -1.6 15 Sand, arkosic (Grains: >lmm = 61% 43 -1.7 20 Sand, arkosic (Grains: >lmm = 44%) 30 -0.4 Silty sand (Grains: