资源环境科技发展态势分析平台

The mechanical response of snow to mixed-mode shear and normal loading is the key ingredient for snow avalanche modeling and strongly depends on microstructural characteristics. A discrete element numerical model was developed, which enables the simulation of large-strain response of snow samples directly described by their full microstructure obtained through X-ray microtomography. The model offers new insights into the failure mechanism as well as postfailure response of snow in mixed-mode loading. Three distinct failure modes are identified, depending on the value of applied normal stress. Above a certain threshold normal stress, the failure is characterized by a structural collapse that decomposes the snow sample into a set of cohesionless grains. It is shown that the collapse is a dynamic process, which, once initiated, develops independently of shearing. This behavior was consistently observed for different snow types, including faceted crystals typically composing weak layers.

Plain Language Summary Snow avalanches are a major natural hazard in mountainous areas due to their destructive power and seemingly unpredictable occurrence. The increase in computing power and development of computation tools in the recent years have opened the prospect of using large-scale computer simulations in order to better understand these catastrophic events. The reliability of a snow avalanche simulation heavily depends on the accuracy of constitutive models used to describe the mechanical behaviour of snow. Snow is, however, a highly complex material, and our understanding of its mechanical behavior is still very limited. Performing systematic mechanical experiments on snow is extremely difficult due to its fragile character. As an alternative, numerical experiments have been developed in the scope of this study to investigate the response of snow to mechanical loading. The obtained results have revealed that snow can fail in different modes. Depending on the level of applied loading, a dramatic collapse of the internal microstructure is observed. Moreover, consistent mechanical behavior was observed for different types of snow, including faceted crystals and rounded grains. The understanding of snow failure mechanisms resulting from this study thus represents a crucial ingredient for the development of large-scale snow avalanche simulations.