Another look at the stability of slopes with linearly increasing undrained strength

Abstract

The paper presents a new look at the stability of slopes with linearly increasing undrained strength with depth. Particular emphasis in the current work is focused on the influence of a firm stratum on the factor of safety and the location of the critical failure surface. Solutions have been obtained by the application of standard optimisation software with some independent finite-element checks. Results are presented in the form of improved charts that give the stability number, and hence the factor of safety, as a function of the depth ratio, strength gradient and slope angle. It is shown that when the strength at the crest is greater than zero, previously published results can greatly underestimate the factor of safety, as the depth to a firm stratum is reduced.