Numerical investigation on p–y method of group piles under static and dynamic loads

The present study aims at scrutinizing the static and dynamic behavior of pile-soil interaction in the context of p–y method using finite element analysis. For this purpose, a series of static and dynamic analyses are carried out for single pile, 2 × 2 and 3 × 3 group piles in homogeneous clayey soil. In the analysis, the nonlinear behavior of soil is taken into account using a kinematic hardening model, while piles are modeled as elastic. The soil model parameters are calibrated using experimental modulus degradation and damping curves. The pile-soil interface is modeled considering normal and shear behavior to account for separation and sliding between soil and pile elements. In the static analyses, variation of pile moments and displacements with depth and the back-calculated p–y curves are evaluated. The soil resistance is directly obtained by extracting the shear and normal forces of the nodes in a pile at any depth. The p-multipliers for 2 × 2 and 3 × 3 group piles are calculated and compared with that of the experiments. The variation of p-multipliers with depth and lateral displacement is also evaluated. In dynamic analyses, first, site response analyses are carried out and validated against one-dimensional results under different loading frequencies. Infinite elements are applied at the boundaries to provide non-reflective boundaries. Later, single, 2 × 2 and 3 × 3 group pile analyses are executed. The influence of loading amplitude and frequency on the response are investigated using moment-depth and displacement-depth relationships. Dynamic p–y curves are back-calculated and the results are deeply assessed by comparing with static curves.