Lateral spreading near deep foundations and influence of soil permeability

Abstract

A three-dimensional finite element (FE) model is calibrated based on a large-scale (1g) shake-table experiment. In this experiment, single piles were subjected to liquefaction-induced lateral spreading. The testing configuration, experimental results, and FE framework are presented and discussed. The presence of piles in this fully saturated ground model caused a significant reduction in the extent of accumulated lateral soil deformation. In this regard, high shear strains, additional to those in the free field, occur as the soil moves around the piles in the downslope direction. The associated shear-induced tendency for dilation increases the effective confinement, and reduces the resulting downslope deformations. As such, an FE parametric study is undertaken to investigate the effect of soil permeability on this observed liquefaction-induced lateral response. As the prescribed soil permeability increased (in the silt–sand range), higher levels of ground lateral deformation occured, albeit with a lower pile head displacement and lateral load. Eventually, high permeability (in the gravels range) precluded the accumulation of significant excess pore pressure, with low levels of both soil and pile lateral displacement. On this basis, permeability is highlighted as a critical potentially primary parameter in dictating the effects of liquefaction-induced lateral load on embedded foundation systems.