Study on mechanics damage mechanism of arch surround reinforced structure under loose load

Abstract

Lining crack is a typical disease of highway tunnels in operation, which affects the long-term operation safety of tunnels. The arch surround is suitable for strengthening tunnel projects with serious cracks due to its characteristics of significantly increasing structural bearing capacity and prolonging service life. However, at present, the damage evolution mechanism of arch surround reinforcement structures under loose loads based on the secondary stress mode is not well understood. Aiming at the above problems, in this paper, based on the load structure method, indoor 1:10 model test of arch surround reinforcement for Grade VI surrounding rock and damaged lining structure is carried out and the stress and deformation law, failure mode and ultimate bearing capacity of tunnel after arch surround reinforcement is explored. On this basis, finite element software is used to simulate the whole process of damage evolution of arch surround reinforced the structure, and to explore the mechanism of mechanical damage evolution of arch surround structure after reinforcement. The results show that the arch surround reinforcement can effectively repair the damaged tunnel and greatly improve its bearing capacity. When the residual bearing capacity of lining is 48.4%, the bearing capacity is increased by 164%. The original structure of the second lining and the reinforced structure of the arch surround are both in large eccentric compression failure. The main damaged parts are the vault and the haunch. The failure of the reinforcing structure of the arch surround is caused by the slip cracking of the combined surface between the second lining and the arch surround. Anchor bolts should be added to improve the shear bearing capacity of the combined surface.