A Discrete Element Framework for Modeling the Mechanical Behaviour of Snow PART I: Mechanical Behaviour and Numerical Model

A framework for investigating the mechanics of snow is proposed based on an advanced
micro-scale approach. Varying strain rates, densities and temperatures are taken into account. Natural hazards i.e. snow avalanches are triggered by snow deforming at low rates, while a large group of industrial applications concerning driving safety or winter sport activities require an understanding of snow behaviour under high deformation rates. On the
micro-scale, snow is considered to consist of ice grains joined by ice bonds to build a porous
structure. Deformation and failure of bonds and the inter-granular collisions of ice grains
determine the macroscopic response under mechanical load. Therefore, this study proposes
an inter-granular bond and collision model for snow based on the discrete element method
(DEM) to describe interaction on a grain-scale. It aims at predicting the mechanical behaviour of ice particles under different strain rates using a unified approach. Thus, the proposed algorithm predicts the displacement of each individual grains due to inter-granular forces and torques that derive from bond deformation and grain collision. For this purpose, the inter-granular characteristics are approximated by an elastic viscous-plastic material law which is based on the temperature-dependent properties of poly-crystalline ice Ih.