Finite Element Primary Exploratory Of Pile-soil Interaction System

The soft foundation has the characteristic of" three low and three high", namely high moisture content, high porosity ratio, high compressibility, low intensity strength, low permeability, low coefficient of consolidation. As natural foundation, the soft foundation can be reinforced by using pile in the engineering. The pile foundation is widely used in variety of engineering fields as an old, traditional, mature method.Establishing numerical model of pile-soil interaction system, numerical method is used to analyze reasonably interaction between soft foundation and pile, and the method of 3D finite element is used to calculate stress and deformation.Because of complex behavior of soil, it is more important to choice a properly constitutive relation to simulate the behavior of soil. The common constitutive models are introduced in the article. Because pile-soil interaction affect internal force and deformation of pile, which make the question more complex, it is important to select properly interface element to describe the mechanics behavior between them. Merits and demerits of kinds of interface element are analyzed deeply in this paper, and on the base of theory in possession it is derived that thin interaction element of Yao Weiming has good compatibility. Based on the nodal mechanics theory and generalized displacement method, equations that the thin-wall cylinder pile is simulated with the beam element are derived. The influence of the number of beam element is researched, and conclusion that the number of beam element and the number of soil layer should be uniform is draw up.Nonlinear characteristic of pile material can not be reflected well by the beam element, and bending deformation of pile can not be reflected by the standard solid element, so the EAS-element are recommended. The calculation results also prove that the EAS element is appropriate for modeling pile. On the base the damage models of concrete and analysis methods of horizontal loading capacity of pile are introduced. Using the method mentioned above thin-wall cylinder piles of the out-gate the engineering in east Punan Shanghai are analyzed, and comparing with testing results it is prove that calculation results are reasonable. Situations of change and development are analyzed which are moment and stress of pile, stress of concrete iron and resisting force of soil under horizontal load. The mechanics of the horizontal load of piles can be gained from the analysis methods.