Combined Anisotropic Viscodamage-Viscoplasticity Model for Rock Under Dynamic Loading

This paper deals with numerical modelling of rock fracture under dynamic loading. For this end, an anisotropic viscodamage-viscoplasticity model for rock is developed. In the viscodamage part of the model, the Rankine criterion indicates the tensile stress states leading to rate-dependent anisotropic damaging. The anisotropy of damage is based on the compliance damage tensor given by the dyadic product of the gradient of the Rankine criterion with itself. In compression, the inelastic deformation and compressive strength degradation is governed by a Mohr-Coulomb viscoplasticity model. The model performance is first demonstrated at the material point level using a two-element model. Then, the dynamic Brazilian disc test, involving both shear and tensile fracture types along with strain rate hardening, on rock is simulated as a laboratory sample level problem.