Dynamic Response of Segment Lining of Overlapped Shield Tunnels Under Train-Induced Vibration Loads

The dynamic response of the overlapped shield tunnels subjected to the train-induced vibration is studied using a nonlinear finite element software. A three-dimensional numerical model is established, and the fabricated segment linings which contain steel bars are used to simulate the shield tunnel. The interaction behaviors, i.e., tensile, shear, and bending, between segment linings are successfully captured by defining the segment lining circumference interface and the joint bolt model. The results show that the dynamic response of the segment linings of the overlapped shield tunnels is affected by the vibration loads caused by the running trains. The additional internal forces generated in the shield tunnels with the fabricated segment linings (joint interfaces are explicitly represented) are larger than those of tunnels which use homogeneous equivalent stiffness model. The opening and staggered deformation response of the joint interfaces is related to the train locations. The axial force and shear response of the bolt under the dynamic load of the train are closely associated with the opening and staggered deformation of joints. The steel spring floating slab can greatly reduce the vertical acceleration and the displacement at the arch bottom of the lower tunnel. The vertical acceleration and the displacement of the bottom arch at the L-III segment lining with the steel spring floating plates are 0.65 times and 0.78 times of the tunnels without the steel spring floating plates, respectively. This study reveals the vibration response features of the overlapped shield tunnels under the train-induced vibration loads, which will help improve the waterproofing capacity and stability of shield tunnels.