Numerical study on dynamic response and failure mechanism of jointed rock with different holes subjected to impact loading

This study employed numerical simulation methods to explore the influence of hole shape, joint spatial position, and confining pressure on the dynamic response and fracturing mode of jointed rock samples subjected to impact loading. The results indicate that hole shape and joint position importantly affects the dynamic strength of the specimens: The jointed rock with straight-wall arched holes show the weakest dynamic strength, while those with hexagonal holes demonstrate the strongest; specimens containing joints J1 and J4 yield the lowest peak strength. However, neither hole shape nor joint position exerts a evident influence on the average elastic modulus of the samples. Joints remarkably alter the crack propagation path and damage process by modifying the refraction effect of stress waves. Joints adjacent to the hole exacerbate damage to the hole chamber, and the directional relationship between joints and stress waves determines the damage sequence and scope of the specimens. When lateral confinement is below a critical threshold, it enhances the mechanical properties of the jointed rock; beyond this threshold, it leads to a reduction in strength. This study provides data support for clarifying the dynamic fracture mechanism of joint-hole combinations and offers a theoretical reference for the stability assessment of defective rocks in engineering practices.