Three-dimensional face stability and deformation analysis of tunneling with TBMs

Abstract

This paper presents three-dimensional (3D) face stability and deformation analysis of the Earth Pressure Balance (EPB) shield tunneling utilized in the construction of Shiraz subway twin-tunnels in Iran by analytical and finite element (FEM) simulation approaches. A FEM program, PLAXIS 3-D Tunnel is used to simulate step-by-step excavation and tunnel construction processes by tunnel boring machine (TBM). The result of FEM in terms of required face stability pressure is compared with analytical calculation using 3-D wedge stability model which is set up based on the limit equilibrium analysis. Heterogeneity of soil layers and 3-D soil arching effect are considered in this model. The results of wedge stability model and FEM simulations are in good agreement with Shiraz subway actual measurements. The numerical finite element procedure is found to be an effective approach for predicting the face stability pressure as well as the deformations and settlements due to EPB shield tunneling.