Behavior of Single Pile in Liquefied Deposits during Earthquakes

Analysis of pile foundations for earthquake loads requires the consideration of inertial loads that result from the soil-pile-superstructure interaction, as well as the evaluation of kinematic interactions that result from the movement of the surrounding soil and the pile. Such soil-pile interaction analyses must consider the stiffness degradation that results from earthquake loading. In the current study, the soil-pile interaction analysis considers stiffness degradation effects for a range of earthquakes with different amplitudes [maximum horizontal acceleration (MHA)], mean time periods, and different durations of earthquakes. Effects of both kinematic and inertial interactions are evaluated using a seismic-deformation method. A computer program was developed using MATLAB for the analysis. Results of a ground-response analysis obtained from a separate study were used for the soil-pile interaction analysis. Pile response for kinematic interactions were validated with the available theoretical solutions in the literature. In addition, kinematic pile response was compared with field observations for an actual earthquake, and the results are presented. Parametric studies were carried out to understand the effect of the presence of a liquefying soil layer, depth of the liquefying layer, etc., and the results are presented. The results indicate that the effect of the depth of the liquefying layer has a significant influence on the pile-bending response and that the peak bending moment occurs at the interface of the liquefying and nonliquefying layers. (C) 2013 American Society of Civil Engineers