Multiscale failure modeling in granular soils

Solving boundary value problems requires sufficiently robust constitutive models to be implemented. In this context, this presentation focuses on slope stability. For this purpose, an advanced micromechanical model for granular soils is presented.This model introduces an intermediate scale made up of elementary hexagonal patterns of adjoining particles. This is a breakthrough with respect to current micromechanical models that generally describe the material by a single distribution of contacts. It is shown how specific degradation laws influence the existence of a bifurcation domain, detected by the vanishing of the determinant of the symmetric part of the constitutive tensor. The bifurcation domain, located inside the plastic limit surface, gathers all mechanical states at which a failure may occur, depending on the incremental loading applied. This basic notion is proved to be fundamental in order to predict the occurrence of large, catastrophic landslides.