College of Engineering

Earthquake-induced liquefaction typically causes soil settlement which may lead to downdrag in axially loaded piles. The drag load generated may overstress the pile or cause significant foundation settlements. Despite significant research progress on the effects of liquefaction on structures and the seismic response of piles, there is still a knowledge gap in the assessment of liquefaction-induced downdrag. This paper discusses different factors that govern this mechanism and presents a parametric study performed using the AASHTO-recommended neutral plane method using displacement-based t-z spring analyses on a simplified profile where liquefiable layer depth and thickness, reconsolidation strains in dense and loose sand, tip conditions, and pile types (L/D ratios) are varied. The results obtained from this preliminary analysis draw some important conclusions regarding the performance of large, medium, and slender piles and are used to design centrifuge model tests to further investigate and understand the complex mechanisms under more realistic conditions