Micromechanical approach to the failure criterion of granular media

The strength of granular media is characterized by the influence of the mean stress which is typical of frictional materials. The aim of the paper is to link the strength of the interfaces between grains and the strength of the granular assembly. The later is viewed as a porous polycrystal. A generalized self-consistent scheme in which the grain is represented by a rigid core surrounded by a deformable interface is developed. First, the linear elastic effective behavior is considered. Then, assuming that the failure of the interfaces is ductile, the effective strength is determined by means of non-linear homogenization techniques. Finally, the case of brittle interfaces is also considered. It is shown that the nature of failure is controlled by the porosity.