ABSTRACT
Composite rock stratum is commonly encountered during tunnel excavation, where the structural planes can easily cause large squeezing deformation, rock burst and other major disasters. Therefore, in order to reduce the risk of tunnel excavation, the discrete element method (DEM) with a new size-dependent contact model is employed to simulate the failure process of composite rock induced by tunnel excavation. Seven inclinations of structural plane are considered. The bond breakage, distribution of maximum principal stress, area ratio of surrounding rock disturbance area, and bond breakage ratio are analyzed. The results show that the bond breakage ratio decreases with the increase of inclination of the soft-hard interbedded rock structural planes. When the angle of the soft-hard interbedded rock structural plane is 0°, the tunnel excavation is found of the most risk.
