Undrained Bearing Capacity of Strip Footing near Slopes Considering the Orientation of Strength Increase

The effect of undrained shear strength profile is an important practical consideration for estimating the bearing capacity of a strip footing placed near slopes or excavations. Previous studies generally assume that the soil strength (c(u)) is uniform or increases linearly with depth but does not vary in a horizontal direction. However, the horizontal variation in soil strength is also commonly found in practice, which is usually caused by various depositional and postdepositional factors. A modified formulation of shear strength profile was defined to characterize this strength variation and was embedded in upper and lower bound finite-element limit analysis (FELA). Seven principal failure modes were revealed and discussed. A comprehensive parametric study was performed to assess the bearing capacity and failure mechanism accounting for the orientation of strength increase. It was found that strength variation in horizontal direction significantly influences the bearing capacity and its associated failure mode. Some novel variation trends of the bearing capacity and the rotation of strip footings were found as well.