A three-dimensional nonlinear study of piles leading to the development of a simplified model.

摘要

The main objective of this work is to examine the influence of the nonlinear behavior of soil on the axial and lateral response of piles due to monotonic and cyclic loading, and to develop a simplified model that will reproduce the main nonlinear features. The specific role of several factors on the response of single piles and pairs of piles is studied first by means of a parametric study based on a three-dimensional finite element model in which the soil is idealized as a modified Drucker-Prager inelastic material. Such factors include relative slippage or separation between a pile and the soil, and soil plasticity away from the pile. Numerical results show that inelastic soil behavior can affect significantly the response of piles. Pile-soil slippage is the most significant inelastic effect under purely axial loading. For lateral loads, however, pile-soil separation and, to a lesser extent, overall inelastic soil deformation, are the crucial factors. Interaction between neighboring piles also is influenced by nonlinear effects. In fact, ignoring these effects can overestimate significantly the amount of interaction between piles.; Guided by the results of the parametric study, a simplified model consisting of coupled, inelastically supported one-dimensional piles is developed in the second part of this work. The validity of the model is assessed by an extensive comparison with numerical results of the more accurate three-dimensional study, as well as with results from experimental field tests. Close agreement is observed between these results and the predictions from the simplified model. This represents an essential step towards a simplified, yet realistic, method of analysis for more general pile groups.