Probabilistic stability analyses of layered excavated slopes

Abstract

The random finite-element method (RFEM) is employed to study the effect of vertical spatial soil variability on the stability of layered excavated slopes. Particular emphasis of the paper is on the critical or ‘worst-case’ vertical spatial correlation length, at which the probability of slope failure reaches a maximum. The RFEM results indicate that layered slopes with a relatively low mean factor of safety or a relatively high coefficient of variation of soil strength are most likely to display the ‘worst-case’ phenomenon. The ‘worst-case’ phenomenon is explained by observing the failure mechanisms in layered soils where the critical spatial correlation length optimises the number of horizontal paths of weaker soil available for the mechanism to pass through.