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Accidental surcharges caused by unauthorized damped waste are the most serious hazard threatening the serviceability and structural safety of shield tunnels in Shanghai, China. It is highly desirable to assess the effect of such accidental surcharges on the performance of shield tunnels. Nevertheless, the occurrence and magnitude of the accidental surcharges are both highly uncertain. In this paper, a probabilistic method is suggested to evaluate the performance of shield tunnels subjected to accidental surcharges, which can systematically consider the uncertainty in the soil properties, the uncertainty in the magnitude of the accidental surcharges, and the uncertainty of the occurrence of the accidental surcharges. The suggested method is used to analyse the potential effect of accidental surcharges on the safety of tunnels in Shanghai. It is found that the maximum height of the surcharges and the mean rate of the surcharges can significantly affect the performance of shield tunnels. Considering the past performance of shield tunnels can increase our confidence in the future performance of the tunnels. The suggested method provides a practical means to quantify the risk posed by the accidental surcharges to the performance of the shield tunnels. [ABSTRACT FROM AUTHOR]

Summary: As numerical models are increasingly used as a design tool in geotechnical engineering, it is highly desirable if geotechnical reliability analysis can be conducted based on numeral models. Currently, the practical use of geotechnical reliability analysis‐based numerical models is still quite limited. In this study, an easy to access method is derived to conduct geotechnical reliability analysis based on numerical models. To facilitate its application, a procedure is outlined to implement the suggested method such that geotechnical reliability analysis can be automated using existing geotechnical numerical packages. The procedure is illustrated in detail with an example, and the source codes provided can be easily adapted to analyze other similar problems. The method described in this paper is used to study the reliability of a deteriorating reinforced concrete drainage culvert in Shanghai, China. The suggested method provides a convenient means for reliability analysis of complex geotechnical problems. [ABSTRACT FROM AUTHOR]