Title: EFFECTS OF LIQUEFACTION-INDUCED GROUND DISPLACEMENTS ON PILE PERFORMANCE IN THE 1995 HYOGOKEN-NAMBU EARTHQUAKE
Abstract: The field performance of various pile foundations that experienced soil liquefaction and lateral spreading in the 1995 Hyogoken-Nambu earthquake are summarized. It is found that (1) damage tends to occur in non-ductile piles and at the interface between liquefied and nonliquefied layers; (2) the piles of a building near the waterfront show different failure modes in the direction perpendicular to the waterfront, while those away from the waterfront show similar deformation patterns. Cyclic and permanent ground displacements during and after earthquakes are estimated from field and aerial photographic surveys as well as analyses of strong motion records, and a simplified method for evaluating those displacements is presented. Pseudo-static analyses using p-y curves are conducted for well-documented case histories of pile foundations on which ground displacements estimated from the proposed method are imposed together with inertial forces from superstructures. The computed results agree reasonably well with the field performance of various pile foundations subjected to different ground movements. These findings confirm that the kinematic forces from cyclic and permanent ground displacements together with their spatial variation could have significant effects on pile damage. The proposed model could be effectively used to estimate deformation and stresses in piles subjected to ground movements.