Experimental and simulation study on compressive failure of rock with pre-Y-shaped cracks

A large number of joints and fissures are prevalent in the rock mass, which has an important influence on the mechanical properties of the rock mass. To study the failure mechanical characteristics of Y-cracked rocks, the paper analyzes the influence of different angles of prefabricated Y-cracked rocks on the mechanical strength characteristics of the rocks and the crack extension evolution through uniaxial compression indoor tests and discrete element PFC2D numerical simulation. The results indicate that the stress-strain curves of rocks containing prefabricated cracks exhibit five stages: the initial pore-fracture compaction stage, the elastic stage, the crack stable development stage, the crack unstable development stage, and the post-peak rupture. The peak strength of the specimen shows an evolutionary process of decreasing, then increasing, and then decreasing with the increase of the Y-shaped crack angle. The failure of the sample is mainly caused by the shear crack expansion at the crack tip. The different Angle cracks directly affect the mechanical properties of the sample and the generation and evolution of new cracks. The final failure of rock is mainly the result of microcrack propagation, convergence and penetration to form macroscopic damage zone. Finally, combined with PFC numerical simulation, the distribution of micro-cracks and the damage pattern of rock damage are compared and analyzed, and it is found that the two are in good agreement, which reflects the rationality of the model.