9223092 Brown During an earthquake, a structure must be provided with some lateral restraint by the foundation because of the horizontal accelerations involved. For piles embedded in liquefaction-susceptible soils, this lateral support requirement can dominate the design of the foundation. The objective of this project is to evaluate the lateral soil resistance exerted on a deep foundation during a strong earthquake which causes the cohesionless soil to liquefy. The aim is to improve the understanding, and provide a better estimate, of the lateral support provided by liquefied soil: currently the lateral resistance of liquefied soil is completely neglected in design, leading to a conservative and therefore more expensive building foundation. Preliminary studies show that even small amounts of soil resistance result in a more economic design. Therefore the lateral soil resistance -- although it is expected to be low -- should be quantified and included in the design. This research project includes a large-scale (nearly full scale) experimental study under laboratory controlled conditions. It consists of a large sand-filled liquefaction tank, in which the sand in liquefied, and an instrumented shaft is accelerated horizontally to measure the lateral resistance of the liquefied soil. This experiment does not attempt to model the complete pile behavior. The complete lateral behavior is modeled numerically once the correct lateral soil resistance in the liquefied zone is measured and understood. ***