An overview is given of the relatively short history, important issues and primary challenges of research on permafrost in cold mountain regions. The systematic application of diverse approaches and technologies contributes to a rapidly growing knowledge base about the existence, characteristics and evolution in time of perennially frozen ground at high altitudes and on steep slopes. These approaches and technologies include (1) drilling, borehole measurement, geophysical sounding, photogrammetry, laser altimetry, GPS/SAR surveying, and miniature temperature data logging in remote areas that are often difficult to access, (2) laboratory investigations (e.g. rheology and stability of ice-rock mixtures), (3) analyses of digital terrain information, (4) numerical simulations (e.g. subsurface thermal conditions under complex topography) and (5) spatial models (e.g. distribution of permafrost where surface and microclimatic conditions are highly variable spatially). A sound knowledge base and improved understanding of governing processes are urgently needed to deal effectively with the consequences of climate change on the evolution of mountain landscapes and, especially, of steep mountain slope hazards as the stabilizing permafrost warms and degrades. Interactions between glaciers and permafrost in cold mountain regions have so far received comparatively little attention and need more systematic investigation.
With the use of creep and constant strain rate (CSR) tests, mathematical formulations were found that describe the thermomechanical behaviour of ice-rich frozen soils. A Glen-type relationship was chosen for the formulation of minimum creep strain rates at temperatures between 4 °C and 1 °C. The shear strength of the material could be described by a MohrCoulomb failure criterion. Furthermore, it was possible to compare the creep behaviour with the strength of similar soils under constant strain rates. The minimum creep strain rate increases proportionally as the temperature approaches the melting point of the ice, which can be attributed to the increasing amount of unfrozen water, which strongly influences the mechanical response. Even though only a few tests could be used for the determination of the angle of friction and the apparent cohesion, the trend showed that the volumetric ice content influences both parameters, but only the latter seems to be influenced by the temperature and the applied compression strain rate.Key words: permafrost, frozen soil, creep, strength.
1 December 2012 in Cold Regions Science and Technology