Reliability analysis of tunnel lining considering soil spatial variability

Abstract

Reliability analysis of the support lining of a shallow circular tunnel excavated in spatially varying soils is presented in the paper. The soil-structure interaction is considered by using a numerical model named the hyperstatic reaction method (HRM). It can provide the internal forces of the tunnel lining in terms of bending moments (M), axial (N) and shear forces (V). The sparse polynomial chaos expansion (SPCE) in combination with the global sensitivity analysis (GSA) is employed to perform the reliability analysis. This method allows reducing the number of the involved input variables according to their sensitivity indices obtained by GSA, and constructing a rational meta-model with limited calls to the mechanical model. Multiple failure modes in the ultimate limit state (ULS) analysis are considered in this study. The individual and system failure probabilities are all provided. The obtained results show that the exceedance of the bending moment resistance is the most probable failure mode, and that the soil spatial variability has a significant influence on the tunnel lining reliability. In addition, the contribution of different soil properties to the variance of the lining forces and the influence of the autocorrelation length on the lining reliability are discussed.