Impact of spatial variability in undrained shear strength on active lateral force in clay

• We explore the mechanisms for the active lateral forces in spatially variable soils.
• We quantify the behavior of seeking the favorable failure path using few key parameters.
• We develop a probabilistic model to simulate the active lateral force.
• The simulated active lateral force behaves similarly to that simulated by limit equilibrium method.

This study explores the mechanism of the active lateral force (Pa) in clay when there is spatial variability in the undrained shear strength. It is shown that the effect of such spatial variability cannot be fully explained by considering the spatial averaging over a prescribed area or line only; the mechanism to seek the favorable failure path is also important. Ignoring this important mechanism is risky, rendering the Pa estimate smaller than the actual Pa value. The mechanism of seeking the favorable failure path is explored, and a probability distribution model for Pa is proposed to characterize this sophisticated mechanism. Furthermore, a simplified procedure is proposed to simulate the Pa samples without the use of the finite element method or limit equilibrium method.