Study on tensile-compression damage and fracture of weak interlayers in block rock masses induced by quasi-resonance

When the frequency of external disturbances approaches the natural frequency of a block rock mass, a quasi-resonance phenomenon occurs. This phenomenon results in a sharp change in the strain of the weak interlayers between rock blocks, accelerating the dynamic damage and fracture of these interlayers. To investigate the dynamic tensile-compression damage and fracture patterns of weak interlayers caused by quasi-resonance in block rock masses, the deformation characteristics of weak interlayers under quasi-resonance conditions were analyzed based on a block rock mass model. Combining the rock dynamic damage fracture criteria, a theoretical and computational analysis of the dynamic damage and fracture of weak interlayers under quasi-resonance was conducted, further studying the dynamic failure patterns. Numerical simulations revealed the damage evolution characteristics of weak interlayers in block rock masses under quasi-resonance conditions. The results indicate that during quasi-resonance in block rock masses, the relative displacement between rock blocks sharply increases, significantly enhancing the strain and damage degree of the weak interlayers. The damage degree of the weak interlayers is highest at low-order quasi-resonance frequencies and is influenced by external disturbance forces and system parameters such as the stiffness, viscosity, and thickness of the weak interlayers and the mass of the rock blocks. When quasi-resonance occurs in block rock masses, the fracture stress increases, but the time from fracture to complete failure is significantly shortened, indicating a substantial decline in residual bearing capacity. This study provides a valuable reference for understanding the dynamic fracture behavior of block rock masses.