Liquefaction induced strength loss and deformation: Simulation and design

Estimates of earthquake-induced deformations for geotechnical structures affected by liquefaction can involve significant uncertainties stemming from the uncertainty in the in-situ residual shear strengths and the effects of pore pressure diffusion (or void redistribution) on those shear strengths. The results of physical model tests involving liquefiable sands with lower-permeability interlayers have demonstrated how various factors can influence the degree to which void redistribution can affect shear strength losses and slope deformations. Numerical simulations using a critical-state compatible constitutive model are shown to reproduce the patterns of void redistribution that were observed in two centrifuge model tests. The constitutive model used in these simulations is described, followed by results for each of the centrifuge model tests. Current limitations in our abilities to account for void redistribution in nonlinear deformation analyses are described, followed by a discussion of how this relates to current design practice for estimating residual shear strengths of liquefied soils.