Comparing model and full-scale experiments on snow avalanche dynamics

Abstract

The paper is a part of a Japanese - Norwegian collaboration on snow avalanche dynamics. The results of model experiments carried out at the Institute of Low Temperature Science, Sapporo are compared with full-scale experiments and theoretical models made by NGI. Avalanching snow is modelled as the flow of granular materials having viscoplastic behaviour. The model experiments indicates that a slip velocity is only found for smooth boundary conditions and there is a distinct velocity gradient at all heights above the bed. The friction at the bed is caused by a Coulomb-friction and a dynamic-friction part, of which the first seems to be most important. The backcalculation of real avalanches also indicates that the Coulomb-friction represents the major energy dissipation. The backcalculated values for the viscosities fits fairly well into existing theories and the results of the model experiments.