Face Stability Analysis of Shield Tunnels in Homogeneous Soil Overlaid by Multilayered Cohesive-Frictional Soils

Abstract

In order to better interpret failure features of the failure of soil in front of tunnel face, a new three-dimensional failure mechanism is proposed to analyze the limit support pressure of the tunnel face in multilayered cohesive-frictional soils. The new failure mechanism is composed of two truncated cones that represent the shear failure band and a distributed force acting on the truncated cones that represents the pressure arch effect. By introducing the concept of Terzaghi earth pressure theory, approximation of limit support pressures is calculated using the limit analysis methods. Then the limit support pressures obtained from the new failure mechanism and the existing approaches are compared, which show that the results obtained from the new mechanism in this paper provide relatively satisfactory results.

Rotational Failure Mechanism for Face Stability of Circular Shield Tunnels in Frictional Soils

“…In the search for the maximum value of σ tc , the optimization procedure is carried out until the band widths of the angles reduce to 0.01°. In addition, the coefficient η defined in equation (10) is selected as η � 10 in the calculations.…”

“…Leca and Dormieux [7] proposed a 3D failure mechanism consisting of one or two conical blocks, and then Mollon et al [8,9] modified it using a multiblock model to obtain more critical support pressures. Many researchers [10][11][12][13][14][15][16][17][18][19][20][21] further developed the mechanism and investigated some effects, such as seepage forces, reinforcement, nonhomogeneous soils, and longitudinal gradient of tunnels. However, these mechanisms are limited to translational failures in frictional soils.…”

Prediction of the Required Supporting Pressure for a Shallow Tunnel in Layered Rock Strata Based on 2D and 3D Upper Bound Limit Analysis

“…Zhang et al [8] investigated the 3D failure characteristics of shallow circular tunnel faces in cohesivefrictional soils. Han et al [9] and Li et al [10,11] investigated the influence of nonhomogeneity and anisotropy of soil masses on the face stability of shallow tunnels. In the abovementioned works, the soils or rocks in the strata are all regarded as the traditional Mohr-Coulomb materials.…”

Numerical Study and Field Monitoring of the Ground Deformation Induced by Large Slurry Shield Tunnelling in Sandy Cobble Ground

“…Ground deformation is inevitably induced by the excavation of the slurry shield tunnel in urban areas, which is negative to the existing structures and pipelines. As a result, a great deal of attention has been attracted all over the world [2,3]. Several approaches, such as the empirical method, model test, numerical simulation, and field monitoring, have been used to estimate the ground deformation during the shield tunnelling.…”