Study on Shear Mechanical Properties and Microscopic Failure Mechanism of Dentate Joints Based on DEM and Laboratory Tests

The stability control of the surrounding rock is greatly influenced by the rock joint's shear mechanical characteristics and deformation failure mechanism. A numerical model of the dentate joints was created using a particle flow discrete element method (DEM). To study the shear mechanical behavior and damage evolution characteristics of the joints, a numerical simulation of the joints shear test under the same normal stress was conducted. Additionally, the joints' shear failure mechanism and failure mode were investigated from a microscopic perspective in conjunction with laboratory tests. The results show that the shear strength steadily increases as the roughness of the rock joints increases and that it rapidly decreases after reaching its peak shear strength, indicating an obvious brittle failure. Varied rock joints exhibit significantly different micro-crack evolution, with rougher rock joints (r = 0.30, r = 0.37) exhibiting greater micro-crack production and crack extension into the model's interior. Rock joint specimens with lower roughness (r = 0.17) had less concentration and fewer areas of contact force concentration. The shear failure mode of the rock joints gradually shifts from abrasion failure mode to snip failure mode as the roughness rises, which is largely compatible with the failure characteristics shown in the laboratory testing. The pattern of micro-crack development within the model specimen and the failure characteristics of the laboratory tests are in good agreement with the distribution characteristics of contact force on the rock joints.