3-DIMENSIONAL NONLINEAR STUDY OF PILES

The main objective of this work is to examine the effect of nonlinear soil behavior on the axial and lateral response of piles to monotonic and cyclic loading with a view towards developing simplified, yet realistic models for representing pile-soil-pile interaction effects. The specific role of pile-soil slippage and separation, and the overall nonlinear soil behavior on the response of single piles and pairs of piles is studied by means of a three-dimensional finite element elastoplastic model that includes interface elements for representing slippage and pile-soil separation. Numerical results indicate that material nonlinearity can significantly affect pile and soil response. Pile-soil slippage is dominant under purely axial loading, while for lateral loads pile-soil separation and generalized inelastic soil deformation are the crucial factors. In fact, ignoring these sources of nonlinearity can lead to greatly overestimating the amount of interaction between piles. Guided by the results of this work, a simplified model, consisting of coupled, inelastic supported one-dimensional piles is developed in the companion paper.