Effect of Physical and Mechanical Properties on Crack Propagation and Dynamic Strength of Rocks with Multiscale Cracks

Abstract

The physical and mechanical properties of rocks significantly affect their deformation and fracture. Currently, the correlation between the physical and mechanical properties and the dynamic deformation and fracture in rocks lacks investigation. When a brittle solid is loaded to failure, it does so by the activation and propagation of cracks in it. The dynamic fracture process in solid materials determines their dynamic properties. The dynamic strength of solid materials is a conditional term that describes the overloading that is due to the delay, which is induced by the kinetics of the dynamic fracture (i.e., the initiation, propagation, and coalescence of cracks). Rock contains complex multiscale internal structures, and the interaction between the multiscale cracks significantly affects the macroscopic mechanical behavior of rocks. Therefore, an analytical model was developed that contains cracks of three scale levels that consider crack propagation, the interaction between the same and different scale level cracks, the degradation of the material properties, and the inertia effect. By adopting this model, the effect of Young’s modulus, Poisson’s ratio, and branching velocity of the crack on the crack propagation and the dynamic strength have been investigated numerically. Young’s modulus, Poisson’s ratio, and the branching velocity of the crack significantly influence the dynamic behavior of rocks.