The Research On Soil Nailed Construction By Three-dimensional Finite Element Modeling (FEM)

As a building foundation pit retaining and protection technology which is easy and celerity to implement, safe and less cost, soil nailed wall is being get more and more application to deep excavation construction. However the research on the theory of behavior and mechanism of the structure behind the application in the engineering practice. Based on the current studies of the behavior and mechanism of the structure, a systematically analyses is carried out with the FEM and the elastic-plastic theory in order to meet the need in engineering. And some valuable conclusions are obtained, which can be taken as references in design and construction. Main research contents as follows:1. Take advantage of the large-scale software ANSYS and ADINA, the experimentation which has been accomplished by professor shen(C. K. Shen) on the Davis campus of the University of California is simulated and the soil nailed wall is analyzed with 3D nonlinear FEM in the paper. After the analysis, compare the two results with the result of the experimentation. In ANSYS analysis, Drucker-Prager model is used as the constitutive model of soil;In ADINA analysis, Mohr- Coulomb model is used as the constitutive model of soil. The ideal elastic model is chosen for the nails and concrete facing. 8-node hexahedral elements is taken for the soil and concrete facing element model;In ANSYS analysis, the double-spring contact model is hold for the element on the interface between soil and nails;In ADINA analysis, the restraint-equation come into being automatically by the software is used as contact model for the element on the interface between soil and nails;The element's "birth and death" is used for the simulation of staged excavation;with the depth ,a increase of soil modulus of elasticity is used;An iterative-incremental method is used to solve nonlinear equation.2. Take advantage of a calculate example , the horizontal displacement of concrete facing, the horizontal displacement of soil, the axial forces of nail, the settlement of soil, the promontory of soil with the staged excavation is analyzed in the paper.3. In the paper a further research is carried out on the influence of soil nail behavior in the perspective of the effect of the length of nails, the angle of nails, and the load on the surface of soil behind the excavation surface, the compounding of different length of nails.