Nonlinear Finite Element Analysis Of Rigid Pile Composite Foundation

In this paper, based on the integration of the Duncan-Chang nonlinear elastic constitutive model, the incremental constitutive equations for the FEM program are deduced and the constitutive integration module is calculated by the user subroutine — UMAT,which is an extremely powerful and flexible tool for analysis. These functions are implemented in the nonlinear FEM software ABAQUS. The program of 2D FEM with Duncan-Chang model is also compiled, and the triaxial test curves are calculated under different confined pressure by this program. The results show that the algorithm with Duncan-Chang model is robust.Research on Interaction of soil and pile under rigid-pile composite foundation has been increasingly received in several years. Plane strain finite element method is used in the study of properties for rigid-pile composite foundation, and two-dimensional finite element analyzing program is compiled. In this program, non-linear elastic (Duncan-Chang model) and elastic-plastic (Drucker-Prager model) constitutive model have been introduced. In order to simulate their possible movements and penetrations between pile and soil, cushion and pile, surface of contact element is set up. In this paper, reaction behavior of rigid pile and surrounding soils under cushion is respectively investigated. Through an example analysis, the reasonability and applicability of the proposed constitutive model are verified. The program discusses the foundation settlement, the pile -soil stress ratio and also the excess pore pressure. It is shown that these two methods can be useful in evaluating the interaction behavior of pile and soils. Through comparing the results between different models, the performance of rigid pile is discussed, and it offers references for the design of rigid-pile composite foundation.