A Three-Dimensional Model of Shield Tunnel considering Interaction of Soil and Lining

The interaction between soil and tunnel lining is an important factor affecting the performance of the tunnel longitudinal structure. In this paper, a three-dimensional model (Model 1) considering the interaction between soil and lining by interface element is built to analyze the response of shield tunnel lining to local surcharge loading. In order to do a comparison, the other model (Model 2) is established without an interface element too. The parametric study of the interface element in Model 1 is carried out, in which parameters such as cohesion, friction angle, normal stiffness, and tangential stiffness are considered. The numerical models are calibrated with experimental results of the model test in the lab obtained from the literature. It is concluded that, among the parameters of the interface element, the changes of cohesion and friction angle have little influence on soil-lining interaction, and the values of normal stiffness and tangential stiffness are more important in simulating soil-lining interaction. The maximum settlement of the tunnel is generally located in the center of the load, and the settlement is symmetric about the center of the load. With the increase of stiffness of soil, the trend of the longitudinal settlement of tunnel is similar, and the maximum settlement of tunnel decreases gradually. The result of Model 1 is much closer to experiment results than Model 2. The general deformation in Model 1 is smaller than the one in Model 2, and the slippage between the soil and lining can be found clearly in Model 1. Because of the interface element in Model 1, the restrain of soil around the lining can be simulated better. Through an engineering project, it can be found that the tunnel deformation can be predicted by the three-dimensional model considering the interaction between soil and lining by interface element well.