Experimental investigations for the modelling of anhydritic swelling claystones

On the variability of squeezing behaviour in tunnelling

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.

Validation of Dynamic Analyses of Dams and Their Equipment is the outcome of a three year cooperation program between CFBR (Comite Francais des Barrages et Reservoirs or French Committee on Large dams) and JCOLD (Japan Commission on Large Dams), and focusses on the dynamic behavior of concrete and embankment dams analyzed based on acceleration records of the JCOLD data base. The book covers a broad range of topics, including simplified and detailed methods of dynamic analysis for the seismic response of concrete and embankment dams compared with measured behavior. The response of embankment dams subjected to a 1.0 g foundation acceleration time history is computed by several analytical methods and compared. The modelling of stress-strain behavior of compacted soils for seismic stability analysis of earth-fill dams and its application for a failed earthfill dam is described. The cracking of the face slab of four faced rockfill dams during earthquakes is analyzed. The seismic behavior of concrete arch dams is discussed by the comparison of numerical and experimental results. Displacement-based seismic assessment of concrete dams is presented. Finally the book contains a comparison between the Japanese and French design criteria of gates and a comparison of the analysis of gates and field measurements. Validation of Dynamic Analyses of Dams and Their Equipment will be useful to professional and academics involved or interested in dam engineering.

Subject index to various sections of Geo abstracts.