Study on the Joint Bending Stiffness of Large-Diameter Shield Tunnel: A Case Study: Fid-Bau Portal

Study on the Joint Bending Stiffness of Large-Diameter Shield Tunnel: A Case Study

Liang, Yu / Huang, Linchong

Abstract Large-diameter shield tunnel is wildly adopted to accommodate the increasing traffic demands in China. As the diameter of the tunnel segmental lining increases, the external loading condition also becomes more complicated, resulting in highly non-uniform and nonlinear internal forces. Depend on the loading condition, the segments joints exhibit different mechanical behaviors. To obtain an accurate evaluation of the internal forces in the segmental lining, it is of great importance to precisely characterize the joint stiffness in prior. In this paper, the internal forces of the tunnel segments, as functions of the joint stiffness, are derived based on force method. Various types of external loading, including the grout buoyancy force, are considered in the derivation. Based on the evaluated loading condition, the mechanical behaviors of the joints are categorized into different cases, in which the effective bending stiffness of the joints is derived accordingly. The coupled nonlinear equations of the joint stiffness and internal forces are solved via fixed-point iteration method. The approach proposed in this work is applied on a large-diameter road tunnel project in China. The calculation results show a good agreement with field measured data and numerical results. It is found that the joint bending stiffness differs from each other greatly at different locations, which is influenced significantly by outer loads. The joint bending stiffness of tunnel can be quickly obtained with this method mentioned in this work.