Constitutive modelling of snow as a cohesive-granular material

Snow material is an example of a geomaterial whose micro-structure plays a significant role in its overall constitutive behaviour. A snow sample can be regarded at the microscopic level as a cohesive granular assembly; the behaviour of ice bonds at the interface of each pair of grains in contact, which has a substantial influence on the overall behaviour, can be expressed in a straightforward manner. This paper derives the constitutive behaviour of the snowpack on the macroscopic level from a microscopic-scale description, taking into account a statistical description of the fabrics. In this approach, the location of each particle does not play a role, but the probability of a grain bond existing in a given direction is investigated. Modelling the creation or the failure of contacts in given directions makes it possible to analyse how the probability density of having contacts in these directions evolves. As an example, the relevance of this constitutive approach is examined using the standard creeping and triaxial tests.