Larger-Scale Siol-Pile Interaction Nonlinear Analysis

Interaction between pile and soil, especially for groups of piles under dynamic load, is still a complex and pop topic of engineering and academic fields. It becomes more complex because of nonlinear characteristic such as the gaps and slippage between pile and soil under the action of earthquake for their different physical characteristic. Traditional m method is used to simulate such interactions, but it's precise and applicability need further study and proof since it can't give out nonlinear property between pile and soil.Emphasis of this paper are put on studying pile-soil interaction, analyzing movement state of pile-soil interface, establishing movement and dynamic boundary conditions, putting forward and adopting transient contact internal force as pending variables which can reflect dynamic interaction mechanism in pile-soil field, building the generalized variational equation using Hamilton principle, Lagrange multiplier and penalty function. Soil-pile system is dispersed with 8-noded element in three dimensions and contact element, and then governing equation of finite element method is built. Also, Wilsion-θmethod is successfully used to transient analysis of soil-pile interaction. Soil-pile interaction analysis program is made which contains viscoelastic boundary and is verified.This paper builds finite element model to study the mechanism of the simplest and basic single pile model, and develops m method model. The results of two models show that they are near in static action but are far in dynamic action. The results of m method are larger.As practical engineering application, this paper discusses seismic appraise of U aqueduct which had used m method to build the model using beam element. Displacements and inner forces of top structure and piles are compared respectively with the models and the program. It shows that displacements and inner forces of piles are comparatively near in no matter static or dynamic, but that of top structure have some difference,the static results are near but the dynamic results have a obvious difference, the most values of FEM are larger than that of m method. That is very important. Although this paper researches only a special engineering, it is valuable to the U aqueduct engineering and other engineering seismic appraise.