Probabilistic analysis of tunneling-induced ground movements in undrained clay: empirical methods revisited

Ground movements resulting from tunnel excavation may cause damage to existing infrastructures in urban areas. Ground response to tunneling has been extensively studied, but the effect of soil stiffness variability on the ground movements remains unclear. This paper presents a probabilistic analysis of greenfield ground movements caused by tunneling in undrained clay. A finite element analysis combined with random field theory in a framework of Monte-Carlo simulations is applied to obtain the stochastic ground movement profiles above tunnels with different depths in clays with spatial variability of undrained stiffness. It is shown that the spatial variation in clay stiffness increases the ground movements, particularly for shallow tunnels. Using the computed results and compiled case history data, the parameters related to the distribution and magnitude of the ground movements are reevaluated with existing empirical predictive methods. The system failure probability, defined as the probability that the maximum ground movements will exceed allowable values, is provided.