Abstract：Because of the significant contact nonlinearity of the joint in shield tunnel, the mechanical analysis of joint has been one difficulty in the structural analysis of shield tunnel. In this paper, the nonlinear deformation of segment joints under the actions of axial force and bending moment is studied, and a new idea of joint mechanical analysis is put forward. By introducing the rigid surface assumption, displacement-based mechanical modeling method of joint and inverse square root filtration function, the normal contact nonlinear mechanical model of joint is established. The results show that: there are several contact states in the joint, and the inverse square root filter function can effectively reflect the normal contact nonlinearity. The mechanical properties of segment joints can be described in the two parts of segment concrete and bolt. The deformation properties of segment concrete are related to displacement eccentricity, and the bolt are related to pretightening force. According to the comparison of the test data of Shiziyang Shield Tunnel and Nanjing Yangtze River Shield Tunnel, The nonlinear joint mechanical model established in this paper is reasonable, and it is consistent with the joint test results.
