Multiscale anisotropic fracturing model of hard rock based on the competitive process of crack propagation

During the excavation of deep engineering, high in situ stress is one prominent feature that often causes instability in the vicinity of underground openings. The propagation and coalescence of cracks in the surrounding rock are characterized by anisotropy under a true triaxial stress state and play a crucial role in the development of stress-induced engineering disasters. Thus, a three-dimensional anisotropic fracturing model of hard rock is proposed to interpret fracturing activities and evaluate the mechanical property deterioration under complex stress conditions. This anisotropic fracturing model is derived from the evolution of microcracks and attributes the inelastic deformation of hard rock to crack propagation and coalescence. Through analyzing the competitive process of crack propagation in different orientations, the stress-induced anisotropic fracturing characteristics and the post-peak brittle-ductile transition could be revealed. Finally, the accuracy and effectiveness of this model are validated. Results show that this proposed anisotropic fracturing model can elucidate the primary characteristics observed in triaxial compression tests, which offers a fresh perspective on comprehending the failure process of hard rock.