Numerical response of pile foundations in granular soils subjected to lateral load

The response of pile foundations under lateral loads are usually analyzed using beam-on-nonlinear-Winkler-foundation (BNWF) model framework employing various forms of empirically derived p–y curves and p-multipliers. In practice, the p–y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. The objective of this study is to evaluate the performance of the BNWF model and to quantify the error in the estimated pile response compared to a rigorous numerical model. BNWF analyses are performed using three sets of p–y curves to evaluate reliability of the procedure. The BNWF model outputs are compared with results of 3D nonlinear finite element (FE) analysis, which are validated via field load test measurements. The BNWF model using API p–y curve produces higher load–displacement curve and peak bending moment compared with the results of the FE model, because empirical p–y curve overestimates the stiffness and underestimates ultimate resistance up to a depth equivalent to four times the pile diameter. The BNWF model overestimates the peak bending moment by approximately 20–30% using both the API and Reese curves. The p-multipliers are revealed to be sensitive on the p–y curve used as input. These results highlight a need to develop updated p–y curves and p-multipliers for improved prediction of the pile response under lateral loading.