Mechanical behaviour of shield tunnel linings strengthened by steel plates spanning circumferential joints

Shield tunnel is susceptible to nearby disturbances, resulting in excessive longitudinal differential deformation, which severely affects the structural performance of the tunnel. Reinforcing the tunnel with steel plates spanning circumferential joints was recently proposed to control the longitudinal differential deformation of the tunnel. However, the acting mechanism and strengthening effects of the steel plates need to be further investigated. Firstly, a multi-scale solid ring-spring numerical model was proposed in the ABAQUS software and validated by available field data. Next, the behaviour of shield tunnel linings reinforced with steel plates in the rings (in-ring scheme) and spanning the rings (across-ring scheme) was compared in detail. Results indicate that the stiffness of circumferential joints can be greatly improved by the across-ring scheme, thereby effectively controlling the longitudinal differential settlement and dislocation. Even when the coupling effect of longitudinal and lateral deformation is present, the across-ring scheme can control lateral deformation more effectively than the in-ring one. Overall, the across-ring scheme is more effective in controlling the deformation of shield tunnels, whether it be longitudinal differential deformation, dislocation, or lateral deformation. This research can provide helpful guidance on deformation control of shield tunnels. In addition, it could be broadly applied in engineering.