Failure mechanisms and energy evolution of jointed rock-like materials under triaxial compression: experimental and numerical simulation study.

To investigate the failure mechanisms and energy evolution of jointed rock under triaxial compression, triaxial compression tests were conducted on rock-like jointed specimens with different joint roughnesses and dip angles under various confining pressures. Based on the particle flow code (PFC), a jointed rock model was established to reveal the mesoscopic failure process of the specimens. The results indicate that increasing joint roughness and confining pressure significantly enhances specimen strength and reduces the anisotropy index, while the peak deviatoric stress strength exhibits a distinct "U-shaped" trend with varying dip angles. Joint-surface characteristics significantly affect key energy components during the failure process, including elastic energy and dissipated energy, and a critical energy value was proposed to distinguish the brittleness–ductility transition. Matrix failure, combination failure, and joint shear failure are the three primary modes of jointed rock failure. Damage typically initiates at the joint surface, subsequently propagates into the matrix, and transitions from tensile microcracks to shear microcracks. The research findings provide a theoretical reference for the stability control of underground engineering.