Study On P-y Curves Of Soil-Pile Interactions In Liquefied Soils

Since the end of last century, some methods to determine the resistance p of soil-pile interactions in liquefied soils have been proposed. Field tests, scale dynamic centrifuge tests and scale shake table tests were conducted to study soil-pile interactions in liquefied soils. As studies on the degradation of cyclic p-y curves during the liquefaction process and soil-pile interactions in the degradation state were few, following researches were done:Generally, the beam on nonlinear Winkler foundation was used to represent soil-pile interactions. Methods to determine the resistance p of soil-pile interactions included the polynomial interpolation, the cubic spilne interpolation and the integral equation etc. As these methods had some shortages, the method to determine the resistance p in liquefied soils was developed based on the weighted residual principle. The method not only avoided the numerical differential, but also could be used to analyse soil-pile interactions in liquefied soils effectively.Shake table test results of soil-pile interactions were analyzed to study the degradation of cyclic p-y curves during the liquefaction process, and calculated cyclic p-y curves were compared with the pseudo static degradation p-y curve. The results showed that the p-multiplier depended not only on the initial relative density, but also on the depth of strata if the pseudo static degradation p-y curve was determined using the p-multiplier method.The greatest bending moment generally located at the upside of the pile in the static lateral bearing capacity of pile model tests, and the bending moment gradually decreased along the pile. Even if the pressure loaded on the stratum surface was different, the distributed bending moment along the pile kept invariability, and the difference was that the bending moment increased with the pressure increasing. When the pressure loaded on the stratum surface was same, the bending moment along the laterally loaded pile was different with the pore water pressure. The topsoil around the pile was destroyed possibly during the liquefaction process, but the subsoil was destroyed impossibly due to the limited stiffness of the pile.