Importance of Lower-Bound Shear Strengths in the Reliability of Spatially Random Clayey Slopes

The random finite element method is used to investigate the effect of including a lower-bound shear strength on the reliability of undrained slopes. The lower bound is represented by the remolded undrained shear strength, which is determined using information about the sensitivity of the clay. This lower-bound strength is used to truncate the left-hand tail of the undrained strength probability distribution. Results indicate that for clayey slopes, the probability of failure is reduced when the lower-bound strength is incorporated in the random field. This reduction allows for reducing the design factor of safety while maintaining the same risk level in the slope design.