Elastic-Plastic FEM Analysis On Flexible Retaining And Protection Structures Of Deep Excavation In Loess Region

Along with a great deal of high buildings set up lately and the city underground space of development, make the problem of the deep pit of foundation excavation and support rise to a very important position. In this paper, on the base of a large quantity of the fundamental theories about the earth pressure calculation and the traditional design methods applied to the protection of the foundation pit, in order to further recognize works together and interaction between loess and flexible retaining wall, the deep pit of foundation excavation and support and loess are seen as a body to study, aimed at flexible retaining wall with anchor and soil nailing internal force to analyze, to find that retaining and protection structures and excavation have effects on itself internal force and around soil displacement mechanism so to further improve retaining and protection structures design and reliability of construction. Combined with the reality project, 3-D nonlinear FEM (ADINA) is used to analyze the performance of excavations and to simulate all the stages during construction of practical excavation. In this paper, firstly problem is brought forward according to background, secondly some design methods, which are suitable for the structure of retaining and protection of foundation excavations in loess, and finite element theory are generalized;The finite element 3D model has been formed and analyzed retaining and protection structures internal force and deformation, displacement of soil behind walk earth pressure, space earth pressure and plastic stress and strain. Some significant conclusions are remarked as follows :(1) Excavation have effect of space ,the maximum and minimum displacement occur at central section and corner;(2) Axial force of the soil nailing and anchor is increased with excavation;(3) The horizontal displacement , vertical displacement and swell displacement of the deep pit of foundation are increased with excavation;(4)Retaining and protection structures forms, deformation and soil property are responsible for earth pressure value;(5) Plastic zone occurs at the bottom of slope.