Displacement-based Design of Shield Tunnel Lining Considering Mobilized Strength of Undrained Clay

Abstract

This paper presents a displacement-performance design method for the shield tunnel based on the mobilized strength design (MSD) theory. Firstly, the nonlinear relationship between the ground volume loss caused by tunnel excavation and the earth pressure was constructed to obtain the real earth pressure on the tunnel lining. Secondly, the nonlinear relationship between the convergence displacement of the lining and the ground resistance was built to acquire the subgrade reaction working on the tunnel lining. Finally, the proposed method was verified by orthogonal numerical experiments and compared with the finite element method (FEM) results. Compared with the FEM, the average deviation of the bending moment and the axial force are about 9% and 1%. The average variation of the bending moment can be reduced to 1% after calibration. The results calculated by this developed method are better than the traditional beam-spring model. Its accuracy is close to the FEM based on the strata-structure concept. Therefore, the proposed method based on MSD theory in this paper has the characteristics of high efficiency and simplicity, which provides a new auxiliary design approach for the structural design of shield tunnels in clay areas.