Numerical analysis of pile groups in multi-layered soil subjected to negative skin friction

Several linear elastic and nonlinear slip models are reported in the literature for predicting negative skin friction on piles and pile groups in consolidating soils. They often produce significantly different results. Moreover, these models are either complex and unfeasible in practice or not capable of taking soil stratification into account, especially in pile groups. These make it difficult for practicing engineers to select appropriate method for predicting negative skin friction. In this thesis, after critically reviewing the existing methods of analysis and examining the inherent mechanisms involved in pile-soil interaction process, a numerical method is proposed for analysis of the negative skin friction on piles and pile groups. The soil response along the depth of the pile is represented by a number of hyperbolic load transfer relationships, each of which relates the load mobilized to the pile at a particular depth and the corresponding relative soil displacement. The method uses conventional laboratory soil test data as input and incorporates nonlinear load transfer mechanism into an iterative finite element framework. A computer program is developed in " Mathematica " programming code to perform this analysis, based on the flowchart developed herein. The results obtained by the proposed procedure compare well with the recent studies and available field data. It is concluded that an iterative finite element approach, coupled with the nonlinear load transfer model, provides a simplified and practical procedure which is capable of predicting the dragload on single or group piles with reasonable accurac