A theory of snow slab failure

Abstract

Existing theories of snow slab failure emphasize failure either in the tensile zone of the slab or along the slab base. The tensile zone theories do not explain measured fracture angles or the observed fact that a necessary condition for extensive fracturing is weakness in the basal plane. On the other hand, the basal theories do not explain where the tensile stress originates and why brittle failure commences in the tensile zone and propagates into the basal plane. A new model is proposed wherein the critical value of the maximum principal stress evaluated at the tensile zone is coupled to the inability of the slab to sustain basal stress. A scale analysis of the equilibrium equations shows that this model predicts the measured fracture angles and large values for the maximum principal stress.