Response of Pile Foundation in Alternate Liquefying and Non-liquefying Layers in Spreading Ground

Abstract

Pile foundations are often preferred in high seismic zones; however, even having high factor of safety against bending strength many historic evidences showed that pile foundations are vulnerable during earthquakes, especially when liquefaction occurs. Major code specification treats pile as beam element subjected to lateral loading, and no definitive provisions are available on analysis method for pile foundation embedded in alternate liquefiable and non-liquefiable soil. The present study is conducted to model layered liquefiable soils for pile foundation response considering state-of-the-art understating along with available code recommendations. Both force-based and displacement-based approaches for typical layered soil profile were chosen in this study. The soil liquefaction depth of the middle layer was varied to understand the behavior during successive stages of liquefaction. The pile-soil interaction was modeled through p-y lateral springs, and suitable reduction was made for the p-y springs which represent liquefaction by various methods available in literature. The static nonlinear analysis was carried out for various models, and the response such as bending moment, shear force, and displacement have been studied. A great variability was seen among the results of pile response for any typical layered soil profile, when different analysis approaches have been adopted.