Stability Analysis of Shield Tunnel Face Considering Spatial Variability of Shear Strength of Argillaceous Siltstone

The traditional research methods used to analyze the stability of shield tunnel face are mostly based on the assumption that the rock mass is homogeneous and isotropic material, which ignores the influence of heterogeneity and discontinuity of rock mass. Therefore, the influence of spatial variability of rock shear strength parameters on the stability of shield tunnel face should be studied. In this study, a random field method was used to establish the numerical model of heterogeneous rock mass, and FEM was used to analyze the failure mechanism and critical face pressure of the shield tunnel face. The influence of autocorrelation length of internal friction angle was analyzed. Failure mechanism and critical face pressure with different variability levels were recorded. Moreover, the reliability method was used to analyze the failure probability of shield tunnel face under different shield pressures, and the suggested face pressure under each variability level was studied. Finally, the failure analysis model was used to analyze the shield tunnel face collapse risk of section B3 of the Pearl River Delta Water Allocation Project. The results showed that the variability level of f has a significant influence on the failure mechanism of the tunnel face. The stratum of high autocorrelation length refers to high suggested face pressure.

Keywords: Tunnel face failure, Shield tunnel, Random field, Autocorrelation Length.