Lateral pile response to monotonie pile head loading

Abstract

This paper presents results from a series of model tests of single vertical piles subjected to lateral monotonic pile head loading. Model tests were carried out in sand under a simulated field stress condition using the hydraulic gradient similitude technique. Studies were focused on examining various factors that affect the soil-pile interaction in terms of P–y curves. It was found that the P–y curves are highly nonlinear and stress-level dependent but are insensitive to the pile head loading conditions. The P–y curves at depths below one pile diameter were found to be normalized by the maximum soil Young's modulus Emax and the pile diameter. Comparison was made between the experimental P–y curves and those recommended by the American Petroleum Institute (API). It was found that the experimental P–y curves were significantly different from the API P–y curves. New procedures for constructing P–y curves are proposed and verified by numerical analyses of the observed model pile response. The results indicate that the API P–y curves based on a hyperbolic tangent function tend to overestimate the pile head stiffness, especially for fixed-head piles due to their stiffer shape in the small to medium pile deflection range. The proposed parabolic P–y curves can better resemble experimental P–y curves and consequently give a better prediction of pile response for both free- and fixed-head conditions. Finally, the proposed procedures were applied to analyze a full-scale pile load test, and good agreement was found between the predictions using the proposed parabolic P–y curves and the field test data. Key words : lateral loads, piles, model tests, sands.