Study On Sensitivity Of Stable Parameters For Rock Slope And Mechanical Parameters Of Excavation Unloading Rock Mass

This paper did sensitivity analysis about stable parameters of rock slope using finite element strength reduction method, and it also did theory analysis and numerical simulation using unloading rock mass mechanics, elastic-plastic theory during the unloading effect process of slope after excavation. The purpose of this paper is studying on the influences of slope unloading effect after excavation to the rock mass mechanical parameters. Then it takes the analytical theory results into the actual slope engineering. It will further perfect the unloading rock mass mechanics theory.Firstly, it completely summarized the research actuality of sensitivity analysis about stable parameters of slope, the research actuality of rock mass failure mechanism, the research actuality of rock mass unloading failure and the research actuality of rock mass excavation unloading effect. Then it proposed the main research contents of this paper. Secondly, it did sensitivity analysis about factors affecting the stability for normal rock slopes. It acquired the situations of some single factors such as cohesion, friction angle, rock density, elastic modulus, poisson ratio and tensile strength to slope safety factor through setting up finite element models.Thirdly, it analyzed the slope excavated process using elastic-plastic theory. It acquired the approximate solution about stress field after excavation unloading through elastic wedge body theory. Then it acquired the changes of stress field under every excavation step based on the theoretical analysis. What's more, it did 1D, 2D and 3D unloading numerical simulation researches for slope rock mass through setting up finite element analytical models of unloading rock mass. It acquired the relationship curves between rock mass mechanics parameters and accumulative excavation unloading quantity of main unloading direction based on the finite element numerical analysis results. And it also acquired quantitative relations between decreased(increased) percentage about the rock mass mechanics parameters and accumulative excavation unloading quantity percentage through polynomial fitting. The rock mass mechanics parameters mainly include deformation modulus, poisson ratio, cohesion and friction angle.Finally, it took the right dam-shoulder slope of Shenxigou power station in Dadu River middle reaches for example to do the finite element analytical calculation. It compared the calculation results'differences between one excavated step without considering excavation unloading effect and many excavated steps with considering excavation unloading effect. And it also acquired the level displacement variable values toward the outside of slope of key points at each unloading zones'boundary.