Particle flow simulation of deformation and failure process of defective rock samples under triaxial compression

To study the influence of dip angle of rock bridge on rock mechanical behavior and crack propagation mechanism, the particle parallel bonding model in the PFC^3D code was used to obtain a group of microscopic parameters, which could reflect the macroscopic mechanical properties of intact granite via the trial and error method. A numerical model of the combination of micro-void and parallel fissures ① and ② under different rock bridge angles was established, and the deformation and failure process of the sample in the triaxial compression were analyzed. Results show there was no significant effect on the ratio of the initiation strength to the peak strength; when α=0° and 75°, the crack propagation modes were similar, and wing cracks were initiated at the inner and outer tips of the fissure ① and ②, and then coalesced with the micro-void; when α=15°, 30°, and 90°, the crack propagation mode was relatively close, the wing cracks could be observed at the tips of the fissures ① and ②; when α=45°, 60°, the cracks grew in a similar manner, there were crack coalescence on the shear plane between the fissures ① and ② and the micro-void, and there were shear cracks at the outer tips of the fissures ① and ②. In this case, both the parallel fissures and the micro-void were on the shear plane; the number of shear cracks was far more numerous than that of the tensile cracks, and the micro-cracks extended from the initial damage zone.