Study On Creep Constitutive Model And Slope Stability Of Permian Weak Interlayer

With the advancement of open-pit mining,the slope of the mine is continuously increased,and the strata exposed thereby are gradually increasing,and the properties of the rock strata are also becoming more and more complex.The various soft strata constantly exposed and the increase of the open surface of the slope will have a serious impact on the stability and safety of the slope.The weak interlayer in the high slope has the characteristics of low strength and obvious rheological effect,which often plays an important role in the stability of the slope.On the basis of fully draw lessons from previous scholars study,by applying experimental analysis,the methods of theoretical analysis,computer simulation,the Permian carbonaceous mud shale weak interlayer shear rheological test results were analyzed,and put forward a kind of weak intercalated shear rheological constitutive model based on the theory of fractional order calculus and nonlinear creep damage,and finished the parameter identification,Microsoft Visual Studio 2015 and FLAC^3Dfinite difference numerical simulation software were used for the secondary development of the rheological constitutive model and the validation of the development model.The long-term stability of the Laoyingzui slope in Jinding Limestone Mine in Sichuan was analyzed,corresponding preventive measures were put forward and the prediction was made in the later stage.The main research conclusions are as follows:(1)Based on the fractional calculus theory and statistical damage theory,a nonlinear shear rheological constitutive model of soft interlayer was proposed.The constitutive model can reflec the deformation process o the three rheological stages of slow down,stable and accelerated rheological of soft interlayer.(2)The parameters of the nonlinear rheological damage model and the shear rheological test results proposed in this paper were fitted by using the special numerical software origin.The fitting results were in good agreement with the rheological test results.The correlation coefficients of the fitting are all 0.95,which showed that the model can better describe the rheological process of the weak interlayer,including the nonlinear accelerated failure stage.(3)The three-dimensional difference scheme of the fractional order rheological damage constitutive model and the stress update equation and stress correction equation used in FLAC^3D were derived.The second development platform provided by FLAC^3D software and Microsoft Visual Studio were used In 2015,the constitutive model proposed in this paper was developed twice,the detailed development process and core code were given,and it was introduced into FLAC^3D for numerical simulation test.Compared with the results of the shear rheological test in the room,good results were obtained,and the applicability and correctness of the development model were verified.(4)Based on the rheological damage constitutive model proposed in this paper and the displacement monitoring data of the slope,the parameters of the rheological model were inversed by using BP neural network and genetic algorithm,and then the development trend of the displacement change of the laoyingzui slope after the landslide cleaning was predicted.According to the results of numerical calculation,the displacement of the monitoring points on the slope increased gradually,but the change rate decreases gradually,and the overall displacement was small.The curve showed the characteristics of slow flow,and had a tendency to stabilize.The maximum displacement was close to 40mm,which will maintain the deformation process of slow creep and become stable gradually.However,it is also necessary to strengthen the monitoring work of eagle mouth slope.In this paper,the rheological shear characteristics of Permian carbonaceous shale weak intercalation were studied,and the engineering application was carried out.The research results can provide certain theoretical guidance and reference for many mines with Permian carbonaceous shale weak intercalation for safe mining and long-term stability analysis.