Reliability Assessment of Diaphragm Wall Deflections in Soft Clays

Abstract

For excavations in built-up areas with deep deposits of soft clays, it is essential to control ground movements to minimize damage to adjacent structures and facilities. This is commonly carried out by controlling the deflections of the retaining wall system. The limiting wall deflection or serviceability limit state is typically taken to be a percentage of the excavation height. In this study, extensive plane strain finite element analyses have been carried out to examine the excavation-induced wall deflections for a deep deposit of soft clay supported by diaphragm walls and bracing. Based on the numerical results, two polynomial regression approaches were used to develop the equations for estimating the maximum wall deflection. This paper describes how the developed equations can be used to perform reliability analysis of the diaphragm wall serviceability limit state to estimate the probability of exceeding the limiting wall deflection.