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The application of geotechnical testing methods in snow research has a long tradition. The aim of this joint research project between the IGT and the Swiss Federal Institute for Snow and Avalanche Research (SLF) Davos is to develop a special purpose triaxial apparatus, to determine the mechanical behavior of snow under low stain rates and to investigate the stess-strain behavior of snow as a basis for newly designed numerical methods in snow engineering. During the first year of this three year project, the triaxial testing device was designed and constructed in the IGT workshops. The apparatus was then transported to the cold rooms of the SLF, Weissfluhjoch Davos, where the snow- samples were gathered and the tests performed. Deformation controlled creep tests with different snow types (from 200 to 400 kg/m3), different confining pressures (from 0 to 30 kPa) and different strain rates (from 10-5 to 10-7 s-1) have been carried out. The visco-elastic material response has been measured and used to calibrate simple spring-dashpot-models (Maxwell, Kelvin and Burger's model). In the next step the test results will be used to develop numerical models, which include stress-history effects and tension-compression asymmetries. In the final step the newly developed consti- tutive laws will be used in practical snow engineering calculations (e.g. de- termination of snow pressures on avalanche defence structures). Later on the knowledge obtained during this project will be used to make progress in the understanding of snow avalanche formation.
Authors:von Moos, Markus and Bucher, Felix and Amann, Peter