Evaluation of negative skin friction effects in pile foundations using 3D nonlinear analysis

The aim of this paper is to evaluate the influence of negative skin friction in pile foundations. Three dimensional nonlinear analyses for a single pile and pile groups were carried out for a specific case and some case studies as well. Contrary to simplified conventional analysis in which the predictions are usually overestimated and could be considered as an upper limit, it was found that the dragload of a pile in a group depends on the surface load, the pile configuration, the pile position in a group, the ultimate skin friction and the interface stiffness. It has been demonstrated that for fixed-head friction pile groups the dragload group effect is significantly greater than in the case of free-head end-bearing pile groups. Moreover, predictions for internal piles have shown considerably smaller dragloads for fixed-head piles, which is in accordance with experimental findings. It has also been demonstrated that when the construction of an embankment precedes the application of the foundation working load, the effect of negative skin friction is considerably smaller than in the reverse case. (c) 2005 Elsevier Ltd. All rights reserved.