Generalized Model for Predicting Lateral Load Response of Open-Ended Steel Pipe Piles in Sandy Soil

This paper presents the results of a study that investigated the lateral response of open-ended pipe piles in sandy soil profiles based on a series of three-dimensional (3D) finite-element (FE) analyses. The analyses, which used an advanced two-surface plasticity constitutive model, were performed for anisotropic sandy soil deposits with varying values of relative density and at-rest lateral effective stress ratio K0. The inclusion of both DR and K0 into predictive relationships leads to more accurate estimation of pile lateral load and pile head motion, which in turn makes it possible to achieve more economic foundation designs. In addition, we investigated the effect of load eccentricity on the lateral load response of pipe piles. A generalized method to estimate the full lateral load response of pipe piles in layered soil is presented. The proposed method incorporates the effect of horizontal effective stress, and is applicable to a wide range of pile geometries, sand relative density, and any load eccentricity. The method fills a gap in knowledge left by studies that primarily focused on either very large-diameter, rigid pipe piles, such as monopiles, or a narrow range of soil conditions. Validation was done by comparison to field results: close agreement was obtained between the predicted and measured pile responses obtained as part of the Pile Soil Analysis (PISA) project. It is demonstrated that the method eliminates the need for independent determination of in situ horizontal effective stress or relative density if cone resistance is available, because these two parameters can be coupled through an equation used to calculate cone resistance; cone resistance can then be used directly in calculations. This is particularly useful given the challenges of measuring K0 for sand in practice.