Anisotropic behavior of excavated layered rock mass subjected to compression considering the joint roughness

The failure mode of the surrounding rock disturbed by the excavation of layered fractured rock is dominated by the spatial distribution of the layered rock. The influence of joint roughness was thoroughly investigated by comparing failure modes, stress-strain curves, and acoustic emission between linear and fractal layered rock models during excavation using numerical simulations. The relationship between the excavation radius and the corresponding peak rock mass strength was discussed. The results show that the deformation modulus and strength of the layered rock mass model gradually decreased with the increase of the excavation size. The rock strength under the effect of excavation size showed that the minimum value was in the range of 45 similar to 60 degrees in the bedding direction. The larger the excavation size of the center of the layered rock mass was, the more unstable the internal structure and the more significant the anisotropic mechanical properties became. The main fracture direction of the layered rock mass was approximately perpendicular to the bedding direction when the surrounding rock was damaged. The spatial directionality of the surrounding rock deformation became more pronounced as the excavation size increased. A significant linear correlation is obtained between the excavation size and the corresponding strength of the layered rock mass.