| The lining of a shield tunnel is made by assembling prefabricated lining pieces which are connected in both the cross-sectional and longitudinal directions. Having the nonlinear structural characteristics, segment joint is the important part of assembled lining pieces structure. The decrease of the lining structural rigidity caused by the joints is one of the important factors which should be considered in the design on the lining of a shield tunnel. The joint stiffness is the important parameter of describing the joint's deformation and mechanical characteristics, which has great effect on the mechanical properties and deformation of tunnel structures. Therefore, it is necessary to analyze the joint's mechanical characteristics and the influence on the lining of the shield tunnel.In this paper, the numeric analysis method is adopted to analyze the mechanical model of the segment joint of the shield tunnel. The jobs described as follows as below:(1) Based on the theoretical analysis on the mechanical behaviors of the segment joint, the mechanical models are built. By using the classical strip method, a program is developed to analyze the segment joint of the shield tunnel.(2) Several FEM models of segment joint are built to simulate the nonlinear mechanical behaviors of segment joint. Some examples show that the 2D/3D FEM model proposed in this paper can satisfy the basic need of the segment joint analysis.(3) Using FEM software, the mechanical characteristics of segment joints are simulated to analyze the important influence factors such as the dimension of segments, the magnitude of loads, the position of bolts, the material propriety of gasket, etc. The joint stiffness, the opening of joints and the stress situation in segments are also deduced.(4) An practical engineering example are calculated to analyze the influence effect of segment joints stiffness on the internal force distribution and structural deformation, which can be referred to the design of lining structures.
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