Research on the Stability and Failure Mechanism of Horizontal Layered Surrounding Rock Tunnel

Research purposes: The construction stability of the tunnel surrounding rock of horizontal layered sandy slate is a difficult point. In order to study the safety and stability of tunnel with surrounding rock of horizontal layered sandy slate under different influence factors, based on the Tongmashan tunnel project, this paper studied stability and failure mechanism of the tunnel surrounding rock of horizontal layered sandy slate. Research conclusions: (1)With the decrease of rock thickness, the difficulty of cavern forming after the blasting is increased, and the collapse extent of the vault increases, and the degree of fragmentation of the side wall and vault increases. (2) With the decrease of hardness of the rock mass and the bonding degree of rock bedding plane, it is difficult to form the cavity from slight damage of the side wall to the whole larger deformation, the most important influence in bedding plane on tunnel cavern formation is fractured zone and overbreak zone. (3) The instability and failure of cavern is the result of interaction between surrounding rock pressure and blasting dynamic load, vault and side wall are most prone to damage, and the failure degree at the vault is the largest, followed by the side wall and the smallest damage at the arch waist. (4)The research results can provide reference for the construction of tunnel with surrounding rock of horizontal layered sandy slate. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.