ABSTRACT
This paper presents the results of a numerical simulation of avalanches performed on a model heap numbering four thousands particles, and using a 2D Contact Dynamics algorithm. The evolution towards instability and the mobilization at the onset of the avalanches are investigated at the scale of a few particle diameters in terms of friction and mobilization of contacts. The density of frictional contacts is shown to be inversely correlated with the total density of contacts. Both of them vary according to the distance to the free surface during avalanches. A large fraction of the weak contact network is composed of frictional contacts even though the induced dissipated energy is smaller than that induced by the strong network. The friction is mobilized during quasi-static periods preceeding destabilization, preluding incoming avalanches.
