Modelling the dynamic failure of brittle rocks using a hybrid continuum-discrete element method with a mixed-mode cohesive fracture model

•Micromechanical simulation of dynamic fracture in rock.•A mixed-mode cohesive fracture constitutive model.•A hybrid continuum-discrete element numerical approach.•Rate dependent behaviour of rock is a consequence of micro-inertia effects on dynamic micro-cracking and fracture.

A cohesive fracture model that combines tension, compression and shear material behaviour is implemented into the hybrid continuum-discrete element method, i.e. Universal Distinct Element Code (UDEC), to simulate fracturing process in rock dynamic tests. The fracture model considers both elastic and inelastic (decomposed to fracture and plastic) displacements, with the norm of the effective inelastic displacement used to control the fracture behaviour. Two numerical examples, including notched semi-circular bending and Brazilian disc tests, are conducted to verify the applicability of the model in simulating the dynamic failure of rocks. Results show that the proposed approach is capable of realistically simulating the load rate effects on the mechanical behaviour of rock materials subjected to dynamic loads.