Probabilistic assessment of groundwater leakage in diaphragm wall joints for deep excavations

A probabilistic method is proposed for conducting groundwater-related hazard assessments that are useful for the risk management of deep excavations in saturated soils in urban areas. The design of deep excavations, construction procedures and execution methods aimed at realizing underground infrastructure are characterized by major uncertainties related to soil properties, construction imperfections and hydrogeological site conditions. During the construction stages, geometrical imperfections and ineffective technologies to control wall seepage can strongly affect the level of risk to the adjacent built environment, leading to severe damages. The aim of this study is to provide an assessment of the leakage probability in reinforced concrete (RC) retaining walls. We model the main geo-structural factors that influence trench stability and the key geometric and technological parameters that affect construction imperfections as relevant random variables. Moreover, through Bayesian updating, useful recommendations are provided regarding the effectiveness and influence of the monitoring phase on reducing the failure probability.