Simplified numerical simulation method for segment joints of shield tunnels

The distribution of the lining stiffness of shield tunnels is uneven for the lining structure composed of several segments and joints, and the weak links are at the segment joints. The correct determination of the segment joint stiffness is crucial for the simulation of construction process of the shield tunnels, the determination of the surface settlement trough and the accurate estimation of ground loss. A simplified method, district modified stiffness method (DMSM), is proposed for simulating segment joints based on the stress and structure of segment joints, which corrects the stiffness at the place of joints and the nearby areas and maintains the stiffness of the rest segment regions. A formula for determing the segment joint stiffness is deduced, and a method for determing the relevant parameters is proposed based on the Saint-Venant principle and the variable stiffness beam theory. The numerical simulation and comparable analysis of deformations of segment joints caused by positive and negative bending moments are performed based on laboratory full-scale tests on segment joints. The results show that the proposed method can simulate the mechanical behaviors of the segment joint well, and is helpful for refined three-dimensional analysis of construction process of the shield tunnels.