Multiscale modeling of cohesive geomaterials with a polycrystalline approach

• A polycrystalline model is proposed for heterogeneous geomaterials.
• Pressure sensitivity and plastic volumetric strain are taken into account.
• An improved robust algorithm is proposed for numerical implementation.
• Validation of the model is presented by comparing numerical and experimental results.

The main objective of this paper is to investigate the macroscopic elastic–plastic behaviors of a class of cohesive geomaterials with the aid of classical polycrystalline schemes. Specific local constitutive equations are proposed to describe the typical features of geomaterials. The local yield criterion for crystallographic sliding systems takes into account the pressure sensitivity and a non-associated plastic potential is introduced to properly describe the plastic dilatancy. Consequently, the concentration law is also modified in order to establish the relationship between the macroscopic stress tensor and the local stress tensor in each mineral grain. Computational aspects associated with the numerical implementation of polycrystalline model are revisited and discussed. The proposed model is applied to a typical polycrystalline rock, granite. After the identification of material parameters, its validity is verified through comparisons between model’s predictions and experimental data on both conventional and true triaxial compression tests.