Experiment and particle flow simulation on mechanical properties and crack evolution mechanism of Brazilian discs containing two flaws

The mechanical behavior of fractured rock in tensile stress environment is a hot topic in underground mining engineering. Here, real surrounding rock of coal mine roadway was simulated by using rock-like materials and the tensile failure behavior of Brazilian discs with intermittent double fissures was investigated experimentally. The deformation response, fracture evolution, and failure mode of rock were analyzed. The fissured disc specimen's discrete element model was proposed in particle flow code (PFC2D). The microforce field, crack, and energy evolution processes of model specimens were discussed. The results showed that the load-displacement curves exhibit single-peak and double-peak types, corresponding to the splitting penetration and wing crack penetration damage modes of the specimen. The fissure angle or rock bridge angle showed a great influence on the evolution of main cracks and secondary cracks. The double-fissured Brazilian disc failed due to the initiation and transfer of microcracks in the stress concentration zone, combined with the continuous propagation and convergence of those microcracks. The splitting failure of the Brazilian disc is a continuous process of strain energy accumulation from the early stage of loading and instantaneous release of strain energy after obtaining the peak strength as the dissipative energy sharply rises.