A three-dimensional micromechanically based model

Granular materials react with complicated mechanical responses when subjected to external loading paths. This leads to sophisticated constitutive formulations requiring large numbers of parameters. A powerful and straightforward way consists in developing micro-mechanical models embedding both micro-scale and meso-scale. This paper proposes a 3D micro-mechanical model taking into account an intermediate scale (meso-scale) that makes it possible to describe a variety of constitutive features in a natural way. The comparison between experimental tests and numerical simulations reveals the predictive capability of this model. Particularly, several simulations are carried out with different confining pressures and initial void ratios, based on the fact that the critical state is quantitatively described without requiring any critical state formulations and parameter. The model mechanism is also analyzed from a microscopic view, wherein the evolution of some key microscopic parameters is investigated.