DOCSLIB.ORG

The Rheology of Frozen Soils

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Rheology of Frozen Soils The Rheology of Frozen Soils Lukas U. Arenson*1, Sarah M. Springman2, Dave C. Sego1 1 Department of Civil & Environmental Engineering, UofA Geotechnical Centre, 3-065 Markin/CNRL Natural Resources Engineering Facility, University of Alberta, Edmonton, Alberta T6G 2W2, Canada 2 Institute for Geotechnical Engineering, ETH Zurich, Wolfgang-Pauli-Str. 15, 8093 Zurich, Switzerland *E-mail: [email protected] Fax: x1.780.492.8198 Received: 2.6.2006, Final version: 2.8.2006 Abstract: The rheological behaviour of frozen soils depends on a number of factors and is complex. Stress and tempera- ture histories as well as the actual composition of the frozen soil are only some aspects that have to be consid- ered when analysing the mechanical response. Recent improvements in measuring methods for laboratory inves- tigations as well as new theoretical models have assisted in developing an improved understanding of the thermo-mechanical processes at play within frozen soils and representation of their response to a range of per- turbations. This review summarises earlier work and the current state of knowledge in the field of frozen soil research. Further, it presents basic concepts as well as current research gaps. Suggestions for future research in the field of frozen soil mechanics are also made. The goal of the review is to heighten awareness of the com- plexity of processes interacting within frozen soils and the need to understand this complexity when develop- ing models for representing this behaviour. Zusammenfassung: Das rheologische Verhalten von gefrorenen Böden hängt von einer grossen Anzahl verschiedener Faktoren ab und ist äusserst komplex. Druck- und Temperaturgeschichte, sowie die Zusammensetzung des gefrorenen Bodens sind nur einige Aspekte, welche betrachtet und berücksichtigt werden müssen, wenn man die mecha- nischen Eigenschaften analysiert. Neue Messtechniken bei Laborversuchen, sowie neue theoretische Modelle haben zu einem verbesserten Verständnis der mechanischen Prozesse gefrorener Böden beigetragen. Dieser Artikel fasst frühere Arbeiten sowie die gegenwärtige Forschung auf diesem Gebiet zusammen. Mit diesem Arti- kel soll das Bewusstsein der Komplexität gefrorener Böden geweckt werden. Es werden Konzepte der gegen- wärtigen Forschung vorgestellt sowie die Richtung zukünftiger Forschungsaktivitäten aufgezeigt. Dem Leser soll bewusst gemacht werden, dass bei der Formulierung von Modellen für gefrorene Böden jeder Situation spe- ziell Rechnung getragen werden muss. Résumé: Le comportement rhéologique des sols congelés dépend d’un grand nombre de facteurs et est complexe. L’his- torique des tensions et des températures ainsi que la composition réelle du sol congelé sont seulement quelques aspects qui doivent être considérés en analysant la réponse mécanique. Les améliorations récentes des méthodes de mesure pour les essais en laboratoire ainsi que de nouveaux modèles théoriques ont aidé à développer une meilleure compréhension des processus thermomécaniques en jeu dans les sols congelés et la représentation de leur réponse à un certain nombre de perturbations. Cet article récapitule les précédents travaux et l’état actuel des connaissances dans le domaine de la recherche sur les sols congelés. De plus, il présente des concepts de base aussi bien que des lacunes présentes dans la recherche actuelle. Des suggestions pour la recherche future dans le domaine de la mécanique des sols congelés sont également faites. L’objectif de l’article est d’intensifier la prise de conscience de la complexité des procédés interactifs agissant dans les sols congelés et de la nécessi- té de comprendre cette complexité en développant des modèles pour représenter ce comportement thermo- mécanique. Key words: frozen soil, permafrost, soil testing, shear strength, creep © Appl. Rheol. 17 (2007) 12147-1 – 12147-14 DOI: 10.1515/arh-2007-0003 Applied Rheology 12147-1 Volume 17 · Issue 1 1 INTRODUCTION the significant frost heave mechanisms. Howev- er, only since the beginning of the 20th Century, The term rheology was originally defined on April and in particular with the ground breaking pub- 29, 1929 by a committee that met in Columbus, lications of Taber in 1929 and 1930 [14, 15], as well Ohio after a proposal by E.C. Bingham and M. as those of Beskow in 1935 [16], were the funda- Reiner. By definition, the term refers to “the study mental processes presented to a wide academic of the deformation and flow of matter” [1 – 3] in audience. The basic concepts introduced at that terms of stress, strain, temperature and time, i.e. time are still generally accepted, as confirmed by it is concerned with the description of the flow Black and Hardenberg [17] in their report on the behaviour of all types of matter [4]. Frozen soil is historical perspective of frost heave research. matter whose thermo-mechanical properties In more recent years, new challenges have should be described in order to carry out stabili- arisen due to problems related to warming ty analysis of permafrost slopes or artificially frozen shafts. Research into the physical proper- ground temperatures associated with per- ties of frozen soils started in the 19th Century. Two mafrost degradation. Slope stability problems main developments were responsible for these have been recorded within mountainous envi- studies. The industrial revolution expanded into ronments [18 – 21] and new impacts on Arctic more remote areas of the Northern hemisphere infrastructure [22 – 25] or coastal zones [26] are that was underlain by permafrost, and artificial expected with the impacts of climate change ground freezing was introduced as a method for [27, 28]. constructing temporary support of structures The emerging demand for knowledge relat- and openings used in both mining and geotech- ed to the mechanical properties of frozen soils nical engineering. with respect to structures in permafrost, artifi- French [5] presents a detailed summary of cial ground freezing or frost action problems has the early works on periglacial geomorphology resulted in a significant number of laboratory and shows that the existence of perennially investigations on a variety of different soil types frozen ground was confirmed as early as during under extensive and varied boundary conditions. the mid 17th Century. Mikhail Vasilyevich Lomo- This vast quantity of research and publications nosov (1711 – 1765) probably offered the first has led to a number of summary papers and known scientific explanation on permafrost [6], reviews. The first section in this paper presents but the first publication on the existence of a selection of such papers to demonstrate the permafrost within the Shergin Well was pub- importance as well as the complexity of this topic lished by von Baer in 1838 [7]. Initial publications in science and engineering. Some related articles on problems related to engineering geocryology have also been published in Applied Rheo- were published in 1885 by a group of four logy [29]. scientists: The instructions for studying the The aim of this paper is to demonstrate the permafrost soils of Siberia. In 1927, Sumgin pub- diversity and variety of frozen soils and to follow lished an important summary of current knowl- up by presenting approaches on how to deal with edge at that time [8]. At about the same time as it. There is no such thing as the typical frozen soil. the engineering properties of permafrost were To understand the mechanical behaviour of a being studied, artificial ground freezing (AGF) frozen soil, factors such as its composition, stress was introduced in Wales (1862) and later in Ger- history, temperature, grain size, type and form, many (1883) by Pötsch [9, 10]. There are endless etc. have to be considered. This review sum- examples where AGF was used to improve soil marises some of the more recent research and properties with nearly no limits in dimension. puts it into context to help with understanding Shaft depths of 900m were achieved in the 1950s and assessing the influence of different variables in Canada, and to date AGF is used for a variety on the mechanical behaviour of various frozen of applications in geotechnical engineering soils. In addition, the review should provide a [e.g. 11, 12]. guide on how to deal with problems related to An important phenomenon observed with- frozen soils and where to find additional infor- in frozen and freezing soils is related to the mation on a particular challenge. It is not intend- dynamics during freezing and frost action. In ed to be a tool for the design of any particular 1854, Volger [13] presented the first evidence of engineered structure. Applied Rheology Volume 17 · Issue 1 12147-2 Permafrost (T<0°C) Artificially Frozen Seasonal Frost Dry (MC = 0%) Frozen Soil (MC > 0%) Rock Soil Segregated Segregated Ice ice not visible ice visible frozen soil, soil freezing and frost action, howev- er, are more focused on engineering, resulting in Individual Ice Poorly Bonded Ice with Soil Inclusions Inclusions substantially fewer manuscripts. Both trends Well Bonded – No Ice Coatings on show a research boom in the seventies that was Excess Ice Particles Ice without Soil Classification Classification Standard Soil Soil Standard Standard Rock Rock Standard Inclusions related to the exploration of the Northern nat- Well Bonded - Random/Irregular Excess Ice Oriented Ice ural resources, predominantly in North America. Formations Representative Layer Thickness The culture of academic publishing has resulted Stratified/Distinctly th 10 Oriented Ice in a skyrocketing increase at the end of the 20 Formations 1.0 Century. 0.1 Ice Content Layer [m] Layer Based on the number of available publica- 0.01 0.1 1 10 100 1000 Maximum Grain Size [mm] tions, it comes as no surprise that various review and state-of-the-art papers have been published. In 1973, Anderson and Morgenstern [30] pre- sented a review on the mechanics of frozen ground. Their publication summarises the important developments, mainly since 1963, with a special focus on the role of unfrozen water. Two additional thorough reviews were present- ed by Ladanyi in 1981 [31] and 1985 [32].
Load more

Recommended publications
  • Sensors and Measurements Discussion
    “Measurements for Assessment of Hydrate Related Geohazards” Report Type: Topical No: 41330R07 Starting March 2002 Ending September 2004 Edited by: R.L. Kleinberg and Emrys Jones September 2004 DOE Award Number: DE-FC26-01NT41330 Submitting Organization: ChevronTexaco Energy Technology Company 2811 Hayes Road Houston, TX 77082 DISCLAIMER “This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.” ii Abstract Natural gas hydrate deposits are found in deep offshore environments. In some cases these deposits overlay conventional oil and gas reservoirs. There are concerns that the presence of hydrates can compromise the safety of exploration and production operations [Hovland and Gudmestad, 2001]. Serious problems related to the instability of wellbores drilled through hydrate formations have been document by Collett and Dallimore, 2002]. A hydrate-related incident in the deep Gulf of Mexico could potentially damage the environment and have significant economic impacts.
    [Show full text]
  • Managing Winter Injury to Trees and Shrubs
    Publication 426-500 Managing Winter Injury to Trees and Shrubs Diane Relf Extension Specialist, Horticulture, and Bonnie Appleton, Extension Specialist, Horticulture; Virginia Tech Reviewed by David Close, Consumer Horticulture and Master Gardener Specialist, Horticulture, Virginia Tech Introduction evergreen needles or leaves. It is worst on the side facing the wind. This can be particularly serious if plants are It is often necessary to provide extra attention to plants near a white house where the sun’s rays reflect off the in the fall to help them over-winter and start spring in side, causing extra damage. peak condition. Understanding certain principles and cultural practices will significantly reduce winter damage Management: Proper watering can is a critical factor in that can be divided into three categories: desiccation, winterizing. If autumn rains have been insufficient, give freezing, and breakage. plants a deep soaking that will supply water to the entire root system before the ground freezes. This practice is Desiccation especially important for evergreens. Watering when there Desiccation, or drying out, is a significant cause of dam- are warm days during January, February, and March is age, particularly on evergreens. Desiccation occurs when also important. water leaves the plant faster than it is taken up. Several environmental factors can influence desiccation. Needles Also, mulching is an important control for erosion and and leaves of evergreens transpire some moisture even loss of water. A 2-inch layer of mulch will reduce water during the winter months. During severely cold weather, loss and help maintain uniform soil moisture around the ground may freeze to a depth beyond the extent of roots.
    [Show full text]
  • Permafrost Soils and Carbon Cycling
    SOIL, 1, 147–171, 2015 www.soil-journal.net/1/147/2015/ doi:10.5194/soil-1-147-2015 SOIL © Author(s) 2015. CC Attribution 3.0 License. Permafrost soils and carbon cycling C. L. Ping1, J. D. Jastrow2, M. T. Jorgenson3, G. J. Michaelson1, and Y. L. Shur4 1Agricultural and Forestry Experiment Station, Palmer Research Center, University of Alaska Fairbanks, 1509 South Georgeson Road, Palmer, AK 99645, USA 2Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA 3Alaska Ecoscience, Fairbanks, AK 99775, USA 4Department of Civil and Environmental Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA Correspondence to: C. L. Ping ([email protected]) Received: 4 October 2014 – Published in SOIL Discuss.: 30 October 2014 Revised: – – Accepted: 24 December 2014 – Published: 5 February 2015 Abstract. Knowledge of soils in the permafrost region has advanced immensely in recent decades, despite the remoteness and inaccessibility of most of the region and the sampling limitations posed by the severe environ- ment. These efforts significantly increased estimates of the amount of organic carbon stored in permafrost-region soils and improved understanding of how pedogenic processes unique to permafrost environments built enor- mous organic carbon stocks during the Quaternary. This knowledge has also called attention to the importance of permafrost-affected soils to the global carbon cycle and the potential vulnerability of the region’s soil or- ganic carbon (SOC) stocks to changing climatic conditions. In this review, we briefly introduce the permafrost characteristics, ice structures, and cryopedogenic processes that shape the development of permafrost-affected soils, and discuss their effects on soil structures and on organic matter distributions within the soil profile.
    [Show full text]
  • Ground Freezing and Frost Heaving Penner, E
    NRC Publications Archive Archives des publications du CNRC Ground freezing and frost heaving Penner, E. For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous. Publisher’s version / Version de l'éditeur: https://doi.org/10.4224/40000788 Canadian Building Digest, 1962-02 NRC Publications Archive Record / Notice des Archives des publications du CNRC : https://nrc-publications.canada.ca/eng/view/object/?id=15f6f5eb-a070-4327-aec4-71472a903119 https://publications-cnrc.canada.ca/fra/voir/objet/?id=15f6f5eb-a070-4327-aec4-71472a903119 Access and use of this website and the material on it are subject to the Terms and Conditions set forth at https://nrc-publications.canada.ca/eng/copyright READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site https://publications-cnrc.canada.ca/fra/droits LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB. Questions? Contact the NRC Publications Archive team at [email protected]. If you wish to email the authors directly, please see the first page of the publication for their contact information. Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à [email protected]. Canadian Building Digest Division of Building Research, National Research Council Canada CBD 26 Ground Freezing and Frost Heaving Originally published February 1962 E.
    [Show full text]
  • Report No. REC-ERC-82-17, “Frost Action in Soil Foundations And
    REC-ERC-82-17 June 1982 Engineering and Research Center U.S. Department of the Interior Bureau of Reclamation 7-2090 (4-81) . .- water ana Power ~ TECHNICAL RE lPORT STANDARD TITLE PAGE 3. RECIPIENT’S CATALOG NO. 5. REPORT DATE Frost Action in Soil Foundations and June 1982 Control of Surface Structure Heaving 6. PERFORMING ORGANIZATION CODE 7. AUTHORIS) 8. PERFORMING ORGANIZATION C. W. Jones, D. G. Miedema and J. S. Watkins REPORT NO. REC-ERC-B2- 17 9. PERFORMING ORGANIZATION NAME AN0 ADDRESS 10. WORK UNIT NO. Bureau of Reclamation Engineering and Research Center 11. CONTRACT OR GRANT NO. Denver, Colorado 80225 13. TYPE OF REPORT AND PERIOD COVERED 12. SPONSORING AGENCY NAME AND ADDRESS Same 14. SPONSORING AGENCY CODE DIBR IS. SUPPLEMENTARY NOTES Microfiche and/or hard copy available at the Engineering and Research Center, Denver, CO I Ed: ROM 1I6 ABSTRACT This is a report on frost action in soil foundations that may influence the performance of irriga- tion structures. The report provides background information and serves as a general guide for design, construction, and operation and maintenance. It also includes information on the mechanics of frost action, field and laboratory investigations of potential frost problems, case histories of frost damage to hydraulic structures, and measures to control detrimental freezing to avoid damage. The structures mentioned include earth embankment dams with appurte- nant structures, canals with linings, and various other concrete canal structures. 7. KEY WORDS ANO OOCU~~ENT *NALY~IS 3. DESCRIPTORS-- / frost action/ frost heaving/ ice lenses/ frost protection/ foundation dis- placements/ behavior (structural) 5.
    [Show full text]
  • Lecture 1 (Pdf)
    GFD 2006 Lecture 1: Introduction to Ice Grae Worster; notes by Rachel Zammett and Devin Conroy March 15, 2007 1 Introduction Our aim in this course is to understand some of the processes associated with ice in the natural environment. Figure 1 shows the location of some of Earth's ice during the north- ern winter. These ice deposits may be categorized as sea ice, ice sheets and shelves, and permafrost. Figure 1: Satellite image showing the ice cover in the northern hemisphere during northern winter, showing sea ice lying in the Arctic basin, the permanent ice sheet over Greenland and permafrost in the exposed land surface. 2 Ice sheets Firstly, figure 1 shows the ice sheet that covers approximately 80% of Greenland. This is about 105 years old and reaches depths of 2{3 kilometers. On large scales, ice can be treated as a highly viscous, non-Newtonian fluid that can flow because it is a polycrystalline solid and contains a percentage of unfrozen water (figure 2). Looking on a scale of about 100µm, 1 Figure 2: Image of the intersection of four ice grains. Between these grains lie the veins containing liquid water and dissolved impurities. The scale bar on this picture is 100 µm. we can see the ice grain junctions and the veins which lie between them. The liquid water contained in the veins between the ice crystals lubricates the flow, allowing the ice to flow more easily. This water can also transport dissolved impurities, which will therefore move relative to the ice crystals; this is important when analyzing ice cores, for example.
    [Show full text]
  • Frost Heaving – Winter Woes Require Summer Remedies”
    “FROST HEAVING – WINTER WOES REQUIRE SUMMER REMEDIES” As summer months approach, the symptoms of frost heaving that were present during the winter often disappear. This does not mean the cause and possible defects have been eliminated. If evidence of frost heaving was present in and around your dwelling last winter, now is the time to indentify possible causes so that repairs can be made before the next winter season. What is “frost heaving”? Frost heaving is a movement of soil caused by the formation of ice lenses within the ground. It is a natural occurrence in Minnesota and other northern climates during the winter and early springtime. Frost heaving occurs when water in the soil expands as it freezes. Generally, water expands by approximately 9% in volume when frozen. This expansion creates significant forces that can move and destroy what had seemingly appeared to be solid construction. Soil movement can vary from something that is barely visible to displacement that is many inches. Causes and consequences of frost heaving. Three conditions typically exist for frost heaving to occur. These are: 1. A sufficiently cold climate (such as found in Minnesota) so that freezing temperatures penetrate into the ground; 2. A sufficient amount of water in the soil; and 3. A type of soil that is frost susceptible When water in soil freezes, an ice lens is formed. Ice lenses collect nearby water in the soil by capillary action, which increases the size of the lens. The force created by the formation of the ice lens will heave soil and move the surface of the ground upward.
    [Show full text]
  • Genesis and Geometry of the Meiklejohn Peak Lime Mud-Mound
    University of Calgary PRISM: University of Calgary's Digital Repository Science Science Research & Publications 2001-12 Genesis and geometry of the Meiklejohn Peak lime mud-mound, Bare Mountain Quadrangle, Nevada, USA: Ordovician limestone with submarine frost heave structures- a possible response to gas clathrate hydrate evolution Krause, Federico F. Elsevier Krause, Frederico F.. (2001). "Genesis and geometry of the Meiklejohn Peak lime mud-mound, Bare Mountain Quadrangle, Nevada, USA: Ordovician limestone with submarine frost heave structures- a possible response to gas clathrate hydrate evolution". In: Carbonate mounds: Sedimentation, organismal response and diagenesis, D. W. Kopaska-Merkel and D. C. Haywick (editors). Sedimentary Geology, 145: 189-213. http://hdl.handle.net/1880/44457 journal article Downloaded from PRISM: https://prism.ucalgary.ca Sedimentary Geology Sedimentary Geology 145 (2001) 189-213 Genesis and geometry of the Meiklejohn Peak lime mud-mound, Bare Mountain Quadrangle, Nevada, USA: Ordovician limestone with submarine frost heave structures-a possible response to gas clathrate hydrate evolution Federico F. Krause* University qfcalgarv. Department of Geology and Geophysics, 2500 Universiiy Drive N. K, Calgaly, Alberta, Canada T2N IN4 Received 3 August 2000; accepted 15 May 2001 Abstract During the Early Middle Ordovician (Early Whiterockian) the Meiklejohn Peak lime mud-mound, a large whaleback or dolphin back dome, grew on a carbonate ramp tens to hundreds of kilometres offshore. This ramp extended from the northwest margin of Laurentia into the open waters of the ancestral Pacific Ocean to the north. The mound developed in an outer ramp environment, in relatively deep and cold water. A steep northern margin with a slope that exceeds 55' characterizes the mound.
    [Show full text]
  • Frost Action and Foundations Penner, E.; Crawford, C
    NRC Publications Archive Archives des publications du CNRC Frost action and foundations Penner, E.; Crawford, C. B. This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC: https://nrc-publications.canada.ca/eng/view/object/?id=72a0db40-5304-473d-848e-a0f831b43c2e https://publications-cnrc.canada.ca/fra/voir/objet/?id=72a0db40-5304-473d-848e-a0f831b43c2e Access and use of this website and the material on it are subject to the Terms and Conditions set forth at https://nrc-publications.canada.ca/eng/copyright READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site https://publications-cnrc.canada.ca/fra/droits LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB. Questions? Contact the NRC Publications Archive team at [email protected]. If you wish to email the authors directly, please see the first page of the publication for their contact information. Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à [email protected].
    [Show full text]
  • Eastern Siberia) Lara Hughes-Allen, Frédéric Bouchard, Isabelle Laurion, Antoine Séjourné, Christelle Marlin, Christine Hatté, F
    Seasonal patterns in greenhouse gas emissions from different types of thermokarst lakes in Central Yakutia (Eastern Siberia) Lara Hughes-Allen, Frédéric Bouchard, Isabelle Laurion, Antoine Séjourné, Christelle Marlin, Christine Hatté, F. Costard, Alexander Fedorov, Alexey Desyatkin To cite this version: Lara Hughes-Allen, Frédéric Bouchard, Isabelle Laurion, Antoine Séjourné, Christelle Marlin, et al.. Seasonal patterns in greenhouse gas emissions from different types of thermokarst lakes in Central Yakutia (Eastern Siberia). Limnology and Oceanography, Association for the Sciences of Limnology and Oceanography, In press, 10.1002/lno.11665. hal-03086290 HAL Id: hal-03086290 https://hal.archives-ouvertes.fr/hal-03086290 Submitted on 8 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Limnol. Oceanogr. 9999, 2020, 1–19 © 2020 Association for the Sciences of Limnology and Oceanography doi: 10.1002/lno.11665 Seasonal patterns in greenhouse gas emissions from thermokarst lakes in Central Yakutia (Eastern Siberia) Lara Hughes-Allen ,1,2* Frédéric
    [Show full text]
  • Motivation for Frost Heave Author(S): JG Dash Source
    Thermomolecular Pressure in Surface Melting: Motivation for Frost Heave Author(s): J. G. Dash Source: Science, New Series, Vol. 246, No. 4937 (Dec. 22, 1989), pp. 1591-1593 Published by: American Association for the Advancement of Science Stable URL: http://www.jstor.org/stable/1704667 Accessed: 22-11-2015 23:33 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. American Association for the Advancement of Science is collaborating with JSTOR to digitize, preserve and extend access to Science. http://www.jstor.org This content downloaded from 132.174.254.159 on Sun, 22 Nov 2015 23:33:34 UTC All use subject to JSTOR Terms and Conditions increasesthe mass input, and melting has GeophysicalUnion, Washington,DC, 1985), pp. 22. Glacio-isostaticuplift ended 4000 to 5000 yearsago 59-85. (A. Weidick,in Geologyof Greenland,A. Escherand little effect.Below the equilibriumline, in- 9. H. J. Zwally,A. C. Brenner,J. A. Major, R. A. W. S. Watt, Eds. (The GeologicalSurvey of Green- creasesln preclpltatlonreduce t le net sum- Bindschadler,J. G. Marsh, Sciet1ce 246, 1587 land, Denmark,1976), p. 450. Figure 3 in (1) mer ablationand partiallyoiset increasesin (1989).
    [Show full text]
  • Frost Heave Properties Assessment of the Soils for the Road Pavement Design
    Frost Heave Properties Assessment of the Soils for the Road Pavement design Final report Customer: VAS “Latvijas Valsts ceļi” Contractor: SIA “Vides eksperti” Sub-contractors: University of Latvia SIA “Ceļu eksperts” Experts: Māris Krievāns, PhD – University of Latvia Jānis Karušs, PhD – University of Latvia Ivars Pavasars, PhD – SIA “Vides eksperti” Aigars Strežs, MSc– SIA “Ceļu eksperts” Rīga 2019 KOPSAVILKUMS Apstiprinu, ___________________________ (vārds, uzvārds, paraksts) Pētniecības projekta nosaukums: Grunšu sala pacēluma īpašību novērtēšana ceļu segas projektēšanas vajadzībām Līguma numurs LVC2018/1.10/1/AC Līguma slēgšanas datums 2018. gada 7. jūnijs Pētniecības projekta stadija Gala ziņojums Starpziņojumu kopējais skaits Viens Ziņojuma nodošanas datums 2019. gada 18. marts Pētniecības projekta stadijas 2018. gada 12. novembris - 2019. gada 18. marts izstrādes periods Lappušu skaits 138 (neieskaitot pielikumus) Disks vai cits datu nesējs (ir/nav) Ir Eksemplāru skaits 1 Pētniecības programma JAUNU TEHNOLOĢIJU IZPĒTES PROGRAMMA 2017. - 2019. GADAM Pētniecības projekta izpildītāji Grāds,Vārds, Uzvārds Paraksts Pētniecības projekta vadītājs PhD, Ivars Pavasars Pētnieks PhD, Jānis Karušs Pētnieks PhD, Māris Krievāns Pētnieks MSc, Aigars Strežs Projektu finansē VAS ″Latvijas valsts ceļi″ / Satiksmes ministrija SIA “Vides eksperti”, Latvijas Universitāte, SIA “Ceļu Partneri eksperts” Apraksts Darba izstrādes ietvaros ir veikts zinātniskās literatūras apskats un analīze, kas koncentrējas uz sala pacēluma teorētiskajiem aspektiem, kā arī apskatīti un salīdzināti pašreiz pasaulē lietotie izpētes standarti un metodes sasaluma un atkusuma ietekmes novērtēšanai gruntīm. Sniegts vispārējs Latvijas klimatisko apstākļu apskats, tendences un analizēti LVC meteoroloģisko staciju dati. Rezultāti atspoguļoti arī grafiski uz Latvijas kartes. Lai novērtētu dažādu Latvijā sastopamo grunšu sala pacēluma īpašības un konstatētu svarīgākos to noteicošos parametrus, savākti Latvijā raksturīgo dažādu grunšu paraugi aptverot pēc iespējas vairāk dažādus grunšu tipus.
    [Show full text]