Combined Effects of Liquefaction-Induced Lateral Spreading and Superstructure Inertial Loads on Pile Foundations-Article

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The study examines how superstructure inertia and liquefaction-induced lateral spreading jointly affect pile foundations. Researchers analyzed a full-scale shake-table test of a 0.25-m-diameter reinforced-concrete pile in ground inclined at 4 degrees, with a nonliquefiable surface crust over saturated sand layers.<br /><br />Large pile strains developed after liquefaction began. At shallow depth within the crust, peak strains were associated with the pile moving upslope under inertial loading while the crust pushed downslope, resisting the motion. These loads were therefore out of phase. At a deeper location, peak strains occurred as inertia pushed the pile downslope, but the crust exerted almost no pressure. Soil displacement had exceeded pile displacement, creating a gap in front of the pile; the pile moved into this gap and outran the soil.<br /><br />The pile later developed a plastic hinge at its base and underwent excessive deformation. The results show that inertial and kinematic loads do not necessarily peak together or combine in a uniform way. Their interaction depends on site and project conditions. Because the findings come from a single test and omit possible crust side-shear effects, they should be treated as one design scenario—not a universal rule—and considered alongside other proposed load-combination approaches.

Keywords

pile foundations

superstructure inertia

liquefaction

lateral spreading

shake-table test

reinforced-concrete pile

pile strains

plastic hinge

kinematic loads

seismic soil-pile interaction