Probabilistic Analysis of Shallow Passive Trapdoor in Cohesive Soil

Abstract

This technical note used the random finite-element method (RFEM) to investigate the influence of soil strength variability on the limit load of a shallow passive trapdoor embedded in cohesive soil. The mean undrained shear strength was held constant while the coefficient of variation and spatial correlation length were varied systematically. For trapdoors against soils with low values of the coefficient of variation, the mean limit load agreed well with the results from a uniform deterministic analysis. For higher values of the coefficient of variation, the mean limit load decreased. By interpreting the Monte Carlo simulations in a probabilistic context, the probability of failure was assessed as a function of the factor of safety based on the mean and the spatial variability of the soil. It was found, for example, that a factor of safety of 2.5 is required to avoid the probability of failure exceeding 5% for soils with strength variability within typical ranges.