Reliability evaluation of segment joint in metro tunnel using MCMC techniques and Bayesian inferential structure

摘要

Shield tunnel is widely used in Shanghai metro system which has numerous joints and buried in saturated soft soil. Therefore, seepage is the most common failure event of tunnel structure. In the present work, a methodology to estimate the reliability of shield tunnel joint was proposed. This methodology contains a two levels hierarchical reliability evaluation. The first level estimation can give the probability distribution function of the seepage frequency as well as the interval estimation of the distribution parameters using MCMC technique and bootstrap based on prior information of tunnel performance so that the epistemic uncertainty can be taken into consideration. The second level estimation can provide the reliability index of the tunnel joint at a specified location along the tunnel structure. To have a more realistic estimation of reliability index, advanced first order reliability method combined with Bayesian inferential structure was employed, in which the longitudinal curvature radius of tunnel structure was considered as posterior information. The proposed approach has also been validated with data extracted from Shanghai metro system with direct inspection and measurement.