Instabilities in alpine permafrost: strength and stiffness in a warming regime


Book Description

Alpine permafrost exists at high altitude at lower latitudes, such as in the Swiss Alps. Accelerating climate change, including rising mean annual air temperature and extreme rainfall conditions in alpine regions induces permafrost degradation. The warming of permafrost causes accelerated creep of rock glaciers, due to increased unfrozen water content and higher deformability of the ice phase. Recently, the development of deepening depressions has been observed in several rock glaciers in Switzerland, and the changes in land surface characteristics and drainage systems may initiate slope instabilities in rock glaciers. The main aim of this thesis is to characterise the strength and stiffness of alpine frozen soil in rock glaciers. To this end, the geotechnical response, such as creep and failure of frozen soil was investigated through a triaxial stress path testing programme with novel measurement systems for detecting acoustic emissions and measuring volumetric change. In addition, the resistance to crack initiation and propagation was investigated through a beam bending test programme on rectangular artificially frozen soil specimens, using the acoustic emission measurement system. The evaluation of laboratory tests on artificially frozen soil specimens implied that the development of deep depressions in rock glaciers occurs through differential creep and thermal degradation, and that the rate of deformation has the potential to lead to instabilities in rock glaciers. A comparison of the simulation results with the experimental data demonstrated that the semi-coupled model was successful in simulating the most important aspects of the temperature-dependent stress-strain relationship for the frozen soil behaviour that was measured at the element scale. This thesis contributes to an understanding of the variations in geotechnical response of alpine permafrost, by investigating the behaviour of artificially frozen soil specimens experimentally and numerically with time and temperature under specific stress paths. However, further investigations are necessary to assess the long-term stability of rock glaciers affected by climate change.




Snow and Ice-Related Hazards, Risks, and Disasters


Book Description

Snow and Ice-Related Hazards, Risks, and Disasters provides you with the latest scientific developments in glacier surges and melting, ice shelf collapses, paleo-climate reconstruction, sea level rise, climate change implications, causality, impacts, preparedness, and mitigation. It takes a geo-scientific approach to the topic while also covering current thinking about directly related social scientific issues that can adversely affect ecosystems and global economies. Puts the contributions from expert oceanographers, geologists, geophysicists, environmental scientists, and climatologists selected by a world-renowned editorial board in your hands Presents the latest research on causality, glacial surges, ice-shelf collapses, sea level rise, climate change implications, and more Numerous tables, maps, diagrams, illustrations and photographs of hazardous processes will be included Features new insights into the implications of climate change on increased melting, collapsing, flooding, methane emissions, and sea level rise




Unstable Alpine Permafrost


Book Description




Instabilities in Alpine Permafrost


Book Description

Alpine permafrost exists at high altitude at lower latitudes, such as in the Swiss Alps. Accelerating climate change, including rising mean annual air temperature and extreme rainfall conditions in alpine regions induces permafrost degradation. The warming of permafrost causes accelerated creep of rock glaciers, due to increased unfrozen water content and higher deformability of the ice phase. Recently, the development of deepening depressions has been observed in several rock glaciers in Switzerland, and the changes in land surface characteristics and drainage systems may initiate slope instabilities in rock glaciers. The main aim of this thesis is to characterise the strength and stiffness of alpine frozen soil in rock glaciers. To this end, the geotechnical response, such as creep and failure of frozen soil was investigated through a triaxial stress path testing programme with novel measurement systems for detecting acoustic emissions and measuring volumetric change. In addition, the resistance to crack initiation and propagation was investigated through a beam bending test programme on rectangular artificially frozen soil specimens, using the acoustic emission measurement system.




Snow and Ice-Related Hazards, Risks, and Disasters


Book Description

Snow and Ice-Related Hazards, Risks, and Disasters, Second Edition, provides you with the latest scientific developments in sea level rise, permafrost degradation, rock/ice avalanches, glacier surges, glacial lake outburst floods, ice shelf collapses, climate change implications, causality, impacts, preparedness and mitigation. The book takes a geo-scientific approach to the topic while also covering current thinking about directly related social scientific issues that can affect ecosystems and global economies. Special emphasis is placed on the rapidly progressing effects from global warming on the cryosphere, perspectives for the future and latest scientific advances, and technological developments. - Presents the latest research on causality, glacial surges, ice-shelf collapses, sea level rise, climate change implications, and more - Contains numerous tables, maps, diagrams, illustrations and photographs of hazardous processes - Features new insights on the implications of climate change, including increased melting, collapsing, flooding, methane emissions, and sea level rise







The High-Mountain Cryosphere


Book Description

This book provides a definitive overview of the global drivers of high-mountain cryosphere change and their implications for people across high-mountain regions.




On the role of constitutive behaviour in the response of squeezing ground to tunnelling


Book Description

Squeezing conditions in tunnelling are characterized by the occurrence of large deformations of the opening or high rock pressure that may overstress the lining. Squeezing is associated with poor quality rock. Tunnelling in squeezing ground involves great uncertainties. It is therefore very important to gain a better understanding of the underlying mechanisms. Triaxial testing is the main source of information in order to understand the mechanical features of squeezing ground. Despite the complexity of the squeezing mechanism and the behaviour observed under relatively simple loading conditions, most of previous research work and engineering design practice considers the ground as a linearly elastic, perfectly plastic material obeying the Mohr-Coulomb yield criterion. While the MC model is capable of predicting the final strength and post-failure volumetric behaviour of the squeezing rock, it cannot map some potentially important pre-failure features or the occasionally observed contractant plastic deformation. In addition, the MC model usually leads to an overestimation of the strength under undrained conditions, which is unsafe for tunnel design. The present thesis mainly addresses the influence of constitutive modelling on predictions about the response of squeezing ground to tunnelling in order to provide some general guidelines for basic engineering analysis. This objective is achieved by investigating the behaviour of squeezing rocks theoretically and experimentally, using samples from several tunnel projects, including the Gotthard base tunnel and the planned Gibraltar strait tunnel.




Geographic Information Science and Mountain Geomorphology


Book Description

From the reviews: "Bishop and Schroder (both, Univ. of Nebraska at Omaha) have brought together an impressive group of practitioners in the relatively new application of geographic information science to mountain geomorphology. In doing so, they have produced valuable, first, overall coverage of a high-tech approach to mountain, three-dimensional research. More than 40 contributing authors discuss a wide range of related aspects.... The book is well bound and well produced; each chapter provides an extensive source of references. The numerous line drawings are clearly reproduced, although the mediocre quality of photographic reproduction limits the value of air photographs and satellite images. As is characteristic of many edited collections, there is some variation in chapter quality. Some of the writing is so dense that it requires minute concentration--one chapter, for instance, has 14 pages of references from a total of 43 pages. Nevertheless, this is a vital compendium for a rapidly expanding field of research. Summing Up: Recommended. Upper-division undergraduates through professionals." (J. D. Ives, Choice, March 2005)




Safety and Reliability


Book Description

These proceedings contain two hundred and eighteen papers representing the work of authors from countries across the world. They cover a wide range of research and applications in safety and reliability issues that concern all types of systems, processes and structures.




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