Abstract: Evolution mechanisms of tunnel surrounding rock loose circle in no layered rock mass and layered rock mass were simulated. Tunnel surrounding rock damage softening and crack initiation, propagation and coalescence until chamber destroyed and became unstable process in layered rock mass of bedding angle were obtained. From the point of view of numerical simulation, engineering stability issue of layered rock mass was qualitatively analyzed.

Key words: No layered rock, Layered rock, Surrounding rock loose circle