Articles | Volume 9, issue 5
The Cryosphere, 9, 1969–1982, 2015
The Cryosphere, 9, 1969–1982, 2015

Research article 20 Oct 2015

Research article | 20 Oct 2015

Microstructure-based modeling of snow mechanics: a discrete element approach

P. Hagenmuller1,2,3, G. Chambon2,3, and M. Naaim2,3 P. Hagenmuller et al.
  • 1Météo-France – CNRS, CNRM-GAME, UMR 3589, CEN, 38400 Saint Martin d'Hères, France
  • 2Irstea, UR ETGR Erosion torrentielle, neige et avalanches, 38402 Saint Martin d'Hères, France
  • 3Université Grenoble Alpes, 38000 Grenoble, France

Abstract. Rapid and large deformations of snow are mainly controlled by grain rearrangements, which occur through the failure of cohesive bonds and the creation of new contacts. We exploit a granular description of snow to develop a discrete element model based on the full 3-D microstructure captured by microtomography. The model assumes that snow is composed of rigid grains interacting through localized contacts accounting for cohesion and friction. The geometry of the grains and of the intergranular bonding system are explicitly defined from microtomographic data using geometrical criteria based on curvature and contiguity. Single grains are represented as rigid clumps of spheres. The model is applied to different snow samples subjected to confined compression tests. A detailed sensitivity analysis shows that artifacts introduced by the modeling approach and the influence of numerical parameters are limited compared to variations due to the geometry of the microstructure. The model shows that the compression behavior of snow is mainly controlled by the density of the samples, but that deviations from a pure density parameterization are not insignificant during the first phase of deformation. In particular, the model correctly predicts that, for a given density, faceted crystals are less resistant to compression than rounded grains or decomposed snow. For larger compression strains, no clear differences between snow types are observed.

Short summary
This paper deals with a mechanical model that exploits a granular description of the snow microstructure. Its originality is that the geometry of the snow grains and of the inter-granular bonding system are explicitly defined from microtomographic data. It enables to model large deformations controlled by grain-rearrangements, which is of particular interest to study the collapse of weak layers or the characterization of the snowpack with an indenter.