Study On The Ultimate Resistance And Ultimate Displacement Of Passive Pile With FEM And Experimentation

Based on the review of existing theories, tests and analytical approaches, the ultimate resistance and ultimate displacement of passive pile have been studied. The main contents of this thesis are as following:Firstly, the literature on research of passive pile and its main problems are reviewed in this thesis. Then several ultimate resistance formulae of passive pile are expounded by the author.Secondly, using plain strain Finite Element Method (FEM) with elastic-perfectly plastic model the effect factors of ultimate resistance of the passive pile are studied. It is found that besides the diameter of the pile, the cohesion and friction angle of surrounding soils, the Yang's modulus, especially Poisson's ratio, also have effect on the ultimate resistance of a passive pile. It may be better to take into account the effect of the Poisson's ratio in the formula of ultimate resistance. According to the results of FEM, a new formula considering the Poisson's ratio and other effect factors is presented, F_u(z)= f(D,σ ,c, φ,v). It is found that the results from FEM are comparable with those from the experiential formula presented, and thus credibility of the method used in this thesis is identified. Then the relationship of the ultimate resistance between round section pile and rectangle section pile is investigated.Thirdly, the author believes that the existing soil bin test in laboratory cannot simulate the conditions of job site reality well and truly, and thus its results cannot be extended to the real pile. A new method is brought forward and the model test device is improved by the author. The new method with improved test device diminishes the disadvantage of the conventional bin test and can simulate the job site conditions well. Then the ultimate resistance of passive pile is studied through the new method with improved test device and the reliability of ultimate resistance formula posed in this thesis is identified through the model test.Finally, based on the analyses of the results of FEM and model test, the ultimate displacement of passive pile is investigated and the formula of the ultimate displacement is suggested, i.e.X_u(z)= f(D,σ_h ,c, φ,E,v). Then the reliability of the ultimate displacement formula is validated through the model test. At last, the relationship of the ultimate displacement between round section pile and rectangle section pile is studied. Based on the analyses of former part this thesis, the distribution of the resistance of passive pile is studied.