Numerical Analysis of Large-Diameter Shield Tunneling Disturbance Considering Stratum Strength Anisotropy

The anisotropic characteristics of natural strata could have a significant effect on the tunneling disturbance of shield tunnels. A shield tunneling disturbance simulation method considering the effect of stratum strength anisotropy is proposed in this study. The proposed method adopts the microstructure tensor theory to characterize the anisotropy effects of the stratum material cohesion c and the internal friction angle φ, and finely simulates the shield tunneling processes, including the shield shell advancement, the lining installation, and the shield tail grouting. The shield tunneling refined simulation method is validated by simulating the tunneling process in a certain section of a super-large-diameter shield tunnel in Wuhu City, Anhui Province, China, with good agreement between the simulated surface settlements on the axial and transverse profiles of the excavated tunnel after tunneling to different lining-ring numbers and the monitoring data. On this basis, according to the anisotropic compression strength property of the layered stratum in other sections, the effect of the stratum shear strength anisotropy on the shield tunneling disturbance is analyzed. The shield tunneling-induced surface settlement under the case considering stratum shear strength parameters anisotropy is obviously greater than that without accounting for the anisotropy, demonstrating the importance of considering strata anisotropy caused by geological structures during shield tunneling disturbance modeling.