Numerical implementation of a new rheological law for argilites

This article presents the numerical implementation of an elastoplastic behavior model suitable for estimating the damage produced when excavating galleries in deep argilite layers. The main rheological features of the model are related to post-peak behavior, brittle fracture, softening and dilatancy effects. Damage of the rock may increase significantly the hydraulic permeability and vice versa. We focus on numerical difficulties such as suitable calculations for plastic flow at very low confinement levels and those resulting from following the confinement factor in such a way that the algorithms converge until physical collapse. The numerical results obtained with a 2D simulation are in good agreement with generally observed phenomena. Dilatancy produces instantaneous cohesion, which disappears with time. Increasing permeability speeds up this tendency.