On the mechanics of snow slab release

Abstract

The mechanics of snow slab release is considered from the viewpoint of mechanics of continua. Its result shows that snow cannot fracture until a critical strain rate and a critical fracture strain is reached in a weak layer of the snowpack. To achieve these conditions, the existence of a “super-weak' zone — where shear stresses from the overburden snow can only insufficiently be transmitted — must be stated. Such super-weak zones interrupt the weak layer and cause stress and strain rate concentrations, making failure possible, which is not the case in homogeneous weak layers. In the first part numerical and analytical investigations are made about stress and strain rate distribution in a snowpack on a uniform slope, containing an initial crack expanding infinitely across the slope. In the second part, starting from the above distributions, the conditions and speed of fracture propagation are considered.