THREE-DIMENSIONAL FEM ANALYSIS ON MECHANICAL CHARACTERISTICS OF DEPING METRO STATION FOUNDATION PIT IN SHANGHAI DURING PROJECT EXCAVATION

摘要

Controlling the displacements of foundation pit walls and supporting structures is one of the most effective measures for ensuring safety of foundation pit construction. Because of this, the accurate displacement computation of foundation pit walls and supporting structures is paid great attention by geotechnical scientists and engineers. In this paper, the three-dimensional displacement field of Deping Station foundation pit, which is part of Shanghai Track Traffic Line 6 project, is computed by means of finite element method (FEM) and ANSYS software. Firstly, the element types and constitutive equations are selected. The continuous underground walls are simulated by 4-node plate elements and elastic constitutive equation. The internal steel bar supports are approximated by three-dimensional bar elements and linear elastic constitutive equation. The soil medium is treated as nonlinear elastic-plastic material and approximated by 8-node elements. The contact surface between continuous underground walls and soil medium is divided into Goodman shell contact elements. Secondly, the displacements and internal forces of supporting structures and soil medium are computed and the final computed results are analyzed. Finally, the sensitivity of computed results to dimensional variation of supporting structures and value variation of soil parameters is analyzed. The research result of current paper is very helpful for geotechnical construction and the development of geotechnical theory.