Some Improvements of a Visco-Plastic Constitutive Model for Snow

Snow is a peculiar example of a granular and low density geomaterial that exists at environmental conditions very close to its melting point. Once snowflakes deposit onto the ground, they start to evolve under the effect of both temperature and stress conditions (i.e., snow metamorphism): the result is therefore a complex three-phase material where an ice skeleton (i.e., snow microstructure) is encompassed by voids filled with air and liquid water. From a mechanical point of view, seasonal snow is therefore characterized by bonding/degradation processes between grains, large inelastic deformations and rate-sensitivity. Moreover, in nature, snow can be found in different shapes and structures having significant differences in terms of mechanical strength and physical properties. Therefore, the need for a constitutive model that can be representative of different types and conditions of snow is of paramount importance. Snow mechanics is indeed a topic of wide interest for many application fields, such as: design and management of structures and infrastructure in cold environments; study of new materials for winter sports and leisure activities; avalanche forecast, release and propagation, etc. In this work, we report on some improvements to an existing constitutive model for snow that was developed in the framework of the nonlinear theory of elasto-visco-plasticity. The numerical implementation was achieved via a fully implicit integration algorithm and a local nonlinear resolving scheme. Finally, some preliminary results are described referring to literature experimental data on snow.