ABSTRACT
Modelling the behaviour of granular materials (sand, gravel, rockfill, etc.) is a complex problem which has not yet received a completely satisfactory solution. This might appear paradoxical because the microstructure of such materials is very simple: particles are sliding over each other and a simulation taking into account a structure made of elastic spheres with friction between them is representative. Nevertheless, this simple microstructure gives rise to a very complex macroscopic behaviour, the description of which is not yet completely satisfactory. In fact, in most normal geotechnical problems, the two basic approximations, linear elasticity and plasticity with the Mohr-Coulomb criterion, are enough to give engineers adequate answers, but it is necessary to go further, to give adequate realistic answers in complex cases.
