Estimation of Transient Forces in Single Pile Embedded in Liquefiable Soil

During the transient phase of liquefaction, i.e., from the onset of liquefaction to the stage of full liquefaction of soil, intrinsic properties of a soil-pile-structure system change causing a significant modification of the transient forces experienced by the pile foundation. However, adequate estimation of transient forces of pile foundation in liquefiable soils for different strong ground motions is not well established. Three-dimensional fully coupled dynamic analyses have been carried out using software OpenSees for piles embedded in single and two-layer soil profiles. Variable permeability of saturated sand has been implemented for higher accuracy in the simulation of cyclic behavior of sand during liquefaction. It was observed that maximum forces in the pile section occur in the transient phase with excess pore pressure ratio in the range of 0.50-0.75 for uniform soil and 0.60-0.90 for layered soil profiles for earthquake motions considered. This study presents the maximum transient forces expected in the pile section in nondimensional forms for a wide range of strong motion parameters, for example, predominant frequency, peak ground acceleration, bracketed duration, and Arias intensity.