Micromechanical modeling of dynamic compressive responses of mesoscopic heterogenous brittle rock

A micromechanical model is developed to investigate microcrack damage mechanism and shear localization of brittle rock subjected to dynamic compressive loads, in which the probability density function describing the distribution of orientations and sizes is assumed to follow the Weibull distribution. To investigate microcracks nucleation and propagation and coalescence, a frictional sliding crack model and the strain energy density factor approach, which is related to crack growth velocity and dynamic fracture toughness of rock material, are applied to provide important insights into how different attributes of the microstructure and strain rate may influence the progressive development of rock shear failure subjected to dynamic compressive loads. It is verified from numerical results that the effect of strain rate on fracture strength of brittle rock is independent of confinement pressure in a certain range of strain rate. The microstructural data indicate that strength heterogeneity increases with an increase in the length of crack, strength decreases with increasing the length of crack. (c) 2007 Elsevier Ltd. All rights reserved.