Numerical study on crack coalescence mechanism of rock specimens containing double parallel cracks

In rock engineering, the propagation and coalescence of cracks significantly impact the stability of the rock mass. To investigate the influence of rock bridge inclination and length on the propagation and coalescence of parallel double cracks, uniaxial compression tests of rock specimens containing parallel double cracks were simulated using the Particle Flow Code (PFC2D). The effects of rock bridge parameters on crack coalescence patterns and the evolution of the displacement field were analyzed. The results indicate that the inclination and length of the rock bridge significantly affect the crack coalescence mechanism. As the rock bridge inclination increases, the stress state for crack coalescence shifts from the post-peak failure stage to the pre-peak unstable crack propagation stage. Additionally, the crack coalescence mode shifts from a shear mode to a tensile mode. Furthermore, a decrease in rock bridge length facilitates crack coalescence.