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.

A continuum-based model for analysis of laterally loaded piles in layered soils

“…In the p-y method the pile is assumed to behave as an Euler-Bernoulli beam with the soil modelled as a series of discretely spaced springs, each connected to one of the pile segments into which the pile is discretised. The springs model the soil response to loading through p-y curves ( p is the unit resistance per unit pile length offered by the springs, and y is the pile deflection), which are developed empirically by adjusting the curves until they match actual load-displacement results Briaud et al, 1984;Yan & Byrne, 1992;Brown et al, 1994;Gabr et al, 1994;Briaud, 1997;Wu et al, 1998;Bransby, 1999;Ashour & Norris, 2000). However, the p-y method often fails to predict pile response (Anderson et al, 2003;Kim et al, 2004), for it is not capable of capturing the complex three-dimensional interaction between the pile and the soil.…”

Analysis of Laterally Loaded Piles in Multilayered Soil Deposits

“…The method of preparation of the p-y curves developed from field observation and experience (Matlock 1970, Reese et al 1974, 1975. The p-y curves used today are mostly obtained either by back fitting the results of numerical analysis (of the fourth-order beam-on-foundation equation) to match the observed deflections in the field or the results of model tests; or by correlating the curves with soil properties determined by laboratory or in-situ tests; or by comparing the results of p-y analysis with other numerical analyses (Matlock 1970, Reese et al 1974, 1975, Brown and Kumar 1989, Yan and Byrne 1992, Brown et al 1994, Gabr et al 1994, Briaud 1997, Wu et al 1998, Bransby 1999, Ashour and Norris 2000, Anderson et al 2003. As a result, the p-y curves are sitespecific and do not take into account the three-dimensional pile-soil interaction.…”

“…As a result, the p-y curves are sitespecific and do not take into account the three-dimensional pile-soil interaction. Considerable judgment is required for using the p-y curves to predict proper pile response; in fact, analyses using the standard p-y curves often are reported to have failed to predict the actual pile loaddeflection response (Yan and Byrne 1992, Anderson et al 2003, Kim et al 2004. For example, Figure 1-11 (adapted from Kim et al 2004) compares the p-y curves obtained from back calculation of the results of model tests on steel piles installed in Nak-Dong river sand, as reported by Kim et al (2004), with the standard p-y curves for sands proposed by Reese et al (1974), O'Neill and Murchinson (1983) and Wesselink et al (1988) that are used in design.…”

Tubular Piles – Buckling Design in a Complex Situation

“…Other suggested p-y curves are based on empirical curve fitting or full-scale tests or centrifuge model tests (cfr. Barton et al, 1983;Yan and Byrne, 1992;Dyson and Randolph, 1997).…”