ABSTRACT
Granular materials consist of grains in contacts and the surrounding voids. The micromechnical behaviour of granular materials is, therefore, inherently discontinuous and heterogeneous. The macroscopic (overall or averaged) behaviour of granular materials is determined not only by how discrete grains are arranged in space, but also by the interactions between them. A constitutive model for granular media based on the continuum approach usually includes a number of material constants, which sometimes have no clear physical meaning. The ambiguous characters of the material constants based on continuum approaches may have their origin in the implicit expressions of the geometry of a packed assembly of particles. Thus, we could expect to analyse granular materials in a more rational manner if we were to make use of discrete element approaches in which the particle arrangement would be modeled explicitly.
