Etude des laves torrentielles sur modèle réduit en similitude des phénomènes naturels

Debris flow small-scale study in similarity with natural events

CEMAGREF, Division Protection contre les Erosions, Domaine Universitaire, B.P. 76, 38402 St-Martin-d'Hères, France

Abstract

Small-scale study of complex debris flows are useful to solve many practical problems. It is hard to carry out a complete similarity between small-scale jlows and natural events. Indeed the material is heterogeneous and upstream discharge is a priori unknown. Here we propose a practical solution : it consists in representing separately the debris flow body using a similar fluid (fine mud), and the front by dispersing coarse particles upon the channel bed. These particles are dragged and pushed by the flood so that they finally form a front with global characteristics analogous to those of natural fronts (larger yield stress than the rest of the fluid, unstable behaviour). Then, analyzing our experimental results concerning such flows, we discuss the conditions to respect for a global similarily.