Study on the damage mechanism of granite containing prefabricated non-through joints

This study conducts uniaxial compression tests on granite samples with prefabricated fissures to investigate the damage mechanism of granite containing non-penetrating joints. These tests combine indoor experiments with three-dimensional discrete element numerical simulations. Stress–strain curves for the rock specimens and the microscopic crack extension mechanism are obtained under varying nodal configurations and by adjusting the inclination angle, penetration, and the number of prefabricated fissures. Results indicated that jointed rocks exhibit a more pronounced plastic deformation capacity than intact rocks when subjected to uniaxial compression. For rock mass strength, the strength of the jointed rock displays a parabolic trend, first decreasing and then increasing, with the increase in joint inclination angle. The minimum value is observed at an inclination angle of 20°–40°. In contrast, the strength of the jointed rock shows a consistent decline with the increasing joint penetration degree and joint count. For rock damage patterns, rock specimens with a nodal inclination angle of 0° primarily experience vertical shear and splitting tensile damage. As the inclination angle increases (0° < α < 90°), the specimens shift towards coplanar shear damage. However, when the joint inclination angle reaches 90°, the mode of failure shifts to a pure form of splitting tensile damage. Specimens with greater penetration lean more towards coplanar shear damage. As the number of nodal joints increases, the rocks transition from shear damage to mixed tensile-shear damage.