Kinematic response of single vertical and batter piles to bidirectional ground motions in liquefiable soil

Abstract

Kinematic responses of single fixed head vertical and batter piles in liquefiable soil under bidirectional ground motions have been studied with fully-coupled three-dimensional nonlinear dynamic analyses. Pressure dependent multi-yield constitutive model has been adopted for modeling the liquefiable sand behavior. The variable permeability of saturated sand during the process of liquefaction process has also been considered. The analyses are carried out for combinations of bidirectional earthquake loading conditions. For this, combination of longitudinal and transverse ground motions as well as combination of longitudinal and vertical motions are considered. The responses of the soil-pile systems under liquefying ground conditions, subjected to these bidirectional ground motions, are compared with the unidirectional loading conditions. Further, the effect of sloping ground on the response of the piles under bidirectional ground motions is also investigated. The developed sectional forces in both vertical and batter piles are lesser under bidirectional motions in comparison to unidirectional ground motion in both level and sloping grounds. However, the pile displacement is more in case of sloping ground under bidirectional ground motions comparing to unidirectional motion.