ABSTRACT
This paper presents a numerical study on the strain-rate effects of rock using a meso-mechanical model based on rate-dependent embedded discontinuity finite elements. The model describes the rock microstructure as cluster of grains represented by Voronoi cells meshed with the standard 3-node triangle elements. The grain boundaries, and thereby the inter-granular fractures, are described by discontinuities pre-embedded into the elements adjacent to the edges of the Voronoi cells. The intra-granular fracture is accounted for by inserting new discontinuities, during the analysis, inside the grains according to the first principal stress criterion. Numerical 2D simulations of uniaxial compression test demonstrate that samples with lower L/D (length/diameter) ratio do have more pronounced strain-rate hardening effect. Therefore, the study corroborates the lateral inertia hypothesis. On the other hand, the numerical simulations of uniaxial tension test show that the rate-dependency is required in the model in order to predict experimentally observed dynamic tensile strength.
