A model for the transmission of contact forces in granular piles

Abstract

Granular matter is fundamentally different from other, more conventional, phases of matter, such as solids and simple liquids. We propose a simple scalar model to study the distribution of weight and the formation of arches in a granular pile subject to gravity. This model simulates dense packaging conditions and introduces the usual heterogeneity observed in these systems. So far, this model was used to study grains in a silo. Here we focus our attention on granular piles in order to avoid the effects of walls and boundary conditions on the contact force distributions. In this pile geometry we can clearly identify a second order phase transition for a given value of the parameter that simulates the presence of slip events in the granular pile. This second order transition is akin to a percolation transition, since some of the critical exponents computed are similar to critical percolation exponents. Similar phenomena were observed in the model of a silo, but in this case wall effects appeared to have signifficant consequences for the behaviour of weight and slip uctuations.