ANALYSIS OF PILES IN LIQUEFIABLE SOILS USING SPRING APPROACH

Abstract

One of the most important elements determining the behaviour of piles built in seismically active areas is soil liquefaction. The models used in this study consider the effect of reduction in soil strength and also in stiffness which is due to the development of pore pressure which leads to soil liquefaction, as well as material nonlinearity. The results from the models are in similar with the observed pile behaviour when compared to standard centrifuge test. From this study it can be concluded that pile behaviour in liquefied soil is influenced by the Arias intensity and, frequency and amplitude of the earthquakes. When the nonlinear behaviour of the soil and the impacts of pore pressure generation are significant, precise ending moments are required. In practise, a "Beam on Non-linear Winkler Foundation technique" is used to analyse laterally loaded piles,in.which.the.lateral.pile-soil.interaction.is.described.as.a.collection of non-linear springs.known.as.p-y.curves.. Load deflection curve or better known as P-Y.curves is of convex shape the slope of which is steep initially and gradually decreases due to increment in soil pile relative displacement. According to recent research, the p-y curve for liquefied soil has a different shape, namely, it is upward concave with practically zero initial.stiffness up to a certain displacement due to the loss of particle-to-particle contact, after which the stiffness increases due to the reengaging.of.the.sand.particles. The purpose of this report is to present a practical method for constructing the.newly.proposed.p-y curves.