Simplified procedure for finite element analysis of the longitudinal performance of shield tunnels considering spatial soil variability in longitudinal direction

A simplified procedure based on finite element method (FEM) is developed in this paper for analyzing the longitudinal performance of shield tunnels considering the longitudinal variation of geotechnical parameters. Herein, the spatial variation of soil properties of the ground under the tunnel is explicitly considered. The validity of the FEM solution is verified by analytical solutions and model tests with various assumed scenarios. The random field theory is employed to model the spatial variation (in the longitudinal domain) of the subgrade reaction coefficient, which is a key soil parameter for FEM analysis of the longitudinal performance of shield tunnels. A hypothetical example is presented to demonstrate the capability of the simplified FEM procedure in analyzing the longitudinal performance of a shield tunnel with spatial soil variability. The results show that the overall settlement of the tunnel is mainly affected by the mean of soil properties, while the extent of the tunnel differential settlement is significantly affected by the variation and scale of fluctuation of soil properties.