Analysis Of Bearing And Deforming Behavior Of Pile Group Under Lateral Load

Pile group is a main pattern of foundation in civil engineering. The vertical pile group loaded laterally has extensively used, so the researches on the bearing and deforming behavior pile group under lateral loads are very important. Previous researches of pile group loaded laterally are carried out mainly by experimental and theoretical analysis. Though a lot of experimental data and researching achievements have been obtained, many problems remain unsolved for the complex nature of pile group loaded laterally. So there are many works in the field are in want to do.With the development of computation method and constitutive theory of soil and the improvement of computer's performance, numerical analytical method becomes grandually a popular tool in the analysis of pile group loaded laterally. In this paper, the finite element method is used to simulate the piles and the near-field soil mass and infinite element method is adopted to simulate distant-field piles and soil as well as interface element is introduced in between piles and soil. Using 3D 20-node iso-parameter, 3D 12-node infinite element and 3D 16-node interface element, a coupled numerical approach for pile group-soil system under lateral loads is set up. A corresponding three-dimensional, nonlinear and elastic-plastic program (EPAGPLL), include two materials and four nonlinear constitutive relations, is worked out by FORTRAN 90 computer language. In the analysis the nonlinear E-u model, K-G model and Cambridge model with two yield surfaces are employed in the analysis of near-field soil, and the nonlinear analysis method is used in the piles-soil interface and distant-field soil.In this paper, using the program (EPAGPLL), the bored testing pile group of the Chinese Architecture Science and Research institute at Luokou area are analysised. The comparisons among analytical results of four constitutive models of soil are made, and the deformation of piles and soil, the soil resistance of the piles, the aclinic displacement of the ground soil before piles and the failure pattern of pile group are discussed in detail. It is concluded that the coupled analytical method in this paper can analyze the bearing and deforming behavior of piles under lateral loads. At the same time, results show that the program is correct and effective.