Analysis of interaction mechanism of piled raft foundation by use of simplified nonlinear model

A simple and practical approach was presented for the analysis of behavior of vertically loaded pile groups embedded in homogeneous and nonhomogeneous soil with the rigid raft in contact with the ground.The interface between soil and raft was divided into a number of approximate square discrete elements.Based on the elasto-plastic analysis of single pile,the interactions between pile and pile,pile and soil,soil and soil were taken into account to determine the stiffness matrix of pile group-soil system.Then the vertical load-settlement relationship of piled raft foundation,axial load distribution in the piles along the depth and the load shared by piles and rafts were obtained.There was no need of discretization of soil and piles along pile shaft in the analysis.Therefore,the solving procedure was simplified.For considering the strength of soil varying along the depth and nonlinear interaction between piles and soil,the theoretical model agreed with the fact quite well.Comparison among the results of the finite element,boundary element,the field tests and the calculated results was carried out,and the feasibility of the present method for the analysis of piled raft foundation was proved.