The Research For The Semi-implicit Return Mapping Algorithm Of The Earth Structure And The Slope Stability Analysis

In this paper, the semi-implicit return mapping algorithm has been developed to cope the integration of the Lade-Duncan elasto-plastic constitutive model. In which, the incremental constitutive equations for the FEM program were deduced and the constitutive integration module is calculated by the user subroutine — UMAT, which is an extremely powerful andflexible tool for analysis, and is available in the nonlinear FEM software ABAQUS. The program of 3D FEM with Lade-Duncan model was completed, and the triaxial test curves were calculated under the different confined pressure by this program. The result shows that the semi-implicit return mapping algorithm with Lade-Duncan model is robust.The two-dimensional nonlinear quasi-static FEM has been used to analysis the slope stability of the rockfill dam. In that part, the strength reduction technique has been quoted to the big nonlinear FEM software ABAQUS. The continuous variety of the strength parameters of slope has been implement in FEM.Taking NUOZHADU core rockfill dam as example, the nonlinear quasi-static FEM calculation and the slope stability analysis have been completed. Drawing the curve between the horizontal displacement of the slope top and deduct factor, the "failure" criterion of slope can been defined, i.e. (△u/△R) ≥ sc, and the control value of the failure criterion sc has been discussed. The applicability of the strength reduction technique byFHM in geotechnical engineering has also been discussed. The paper provided salutary experiment to investigation of the geotechnical engineering by the FEM strength reduction technique.