The damage evolution mechanism of stratified surrounding rocks in deep tunnels is of great significance for disaster early warning. To investigate this mechanism，MatDEM software was employed to construct numerical models that simulate the overloading failure of rock samples under different deep stress conditions. Numerical analysis was conducted on the damage evolution process during mechanical overloading. From three aspects—triaxial stress response characteristics，fracture propagation patterns，and velocity field distribution related to rockburst—the influences of structural effects and confining pressure effects were systematically examined. The results demonstrate that the primary failure consistently initiates at the regions with maximum stress concentration. The fracture evolution process is found to effectively distinguish between tensile cracks and shear cracks. The research results provide a theoretical basis for the process control and short-term warning of collapse disasters in deep-buried tunnel engineering.