A Three-dimensional Finite Element Study to Obtain P-y Curves for Sand

For pile foundations subjected to lateral loads, an analysis method should account for the response of the combined soil-pile system. Current practice for pile-soil interaction analysis usually employs a series of springs to model the lateral behavior of soil-pile interaction. In this method, the force (p) – deformation (y) function, widely known as p-y curve, of the spring characterizes the pile-soil interaction mechanism. For sand, traditional p-y curves are independent of loading conditions with an initial slope assumed to vary linearly with depth. This paper presents a framework using three-dimensional finite element method (3D FEM) nonlinear analysis to estimate the p-y curves response characteristics for sand. A linear analysis was first conducted as a routine check on laterally loaded piles using the 3D FEM. A nonlinear 3D FEM was then carried out to model full-scale field lateral pile response. Different meshes were examined to obtain a reliable 3D FEM representation for pile-soil interaction. This procedure was subsequently used to study p-y curves for sand under other conditions. It is found that at greater depth, p-y curves show some dependence on loading conditions. Near ground surface, p-y curves show little influence of loading conditions. In this pilot study, the initial slope of the p-y curves appeared to be about the same at different depths.