Safety Analysis of the Secondary Lining Structure of Existing Tunnel with Cracks

Because cracking of the secondary lining is one of the most common diseases in road tunnel, it is of great practical significance and theoretical value to analysis and research on the safety of lining structure of existing tunnel with cracks. Based on crack models of fracture mechanics, the calculation method of safety evaluation for the secondary lining structure of existing tunnel with cracks was discussed through numerical analysis. The bearing capacity of non - destructive lining and cracked lining was analyzed and compared by model tests. Results showed: (1) the finite element method of fracture mechanics could be used to evaluate the safety of the secondary lining structure of existing tunnel with cracks. (2) The size order of the required load when the cracks occurred in the different parts; The arch foot is smaller than the vault; the vault is smaller than the haunch; the haunch is smaller than the invert. (3) When the crack was located at the crown and arch foot, it had the most significant influence on the safety of lining structure. (4) The bearing capacity of the lining structure declined because of cracks, and it decreased by 37.5% when there was longitudinal crack at the bottom of the inverted arch of tunnel.