P-Y Lateral Pile Analyses Accounting for Arbitrary Loading Directions and Calibration Uncertainty

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A bounding surface plasticity p-y model accommodating pile lateral loading in arbitrary directions with respect to the pile axis is demonstrated via back-analysis of test piles. The demonstration analyses include: planar conditions, three-dimensional conditions with asymmetric cyclic loading, and Monte Carlo investigations of the influence of calibration choices. The p‑y model and its host finite element program are implemented in the MATLAB programing environment. Monte Carlo simulations investigating modelling uncertainty are accomplished efficiently when taking advantage of MATLAB’s parallel processing capability. Analysis results are compared to those observed for nine test piles at the Cowden site with diameters 0.272 m, 0.762 m and 2 m having length-to-diameter ratios between 3 and 10. The implemented p-y model is based upon and is a natural extension of the traditional API methodology. The modelling technique accurately reproduces the observed response characteristics of piles in a challenging soil profile with considerable uncertainty in its strength characteristics. It is robust, theoretically rigorous, efficient and requires the same level of effort as traditional p-y analyses. The results are easily interpreted by designers familiar with the p-y method. The characteristic responses of the p-y model under biaxial loading compare favorably to those from finite element elastic-plastic planar continuum analyses as well as small-scale physical tests on rigid piles.