Study On The Stability Of The Slope Of Gently Dipping And Soft Interlayer Rock Mass

In this paper,a large-scale gentle dip and weak intercalated rock mass slope in Renhuai City,Guizhou Province is used as the model background.The ideal elastoplastic model and strain based on the finite difference method in the principle of FLAC3 D numerical simulation software strength reduction method are adopted.Three methods of softening model study on stability and asymptotic failure characteristics of slope excavation after unloading.The main research contents are as follows:(1)Starting from the definition of weak interlayer,the weak interlayer is introduced,then the material composition and classification and the corresponding engineering characteristics are expounded.The asymptotic loss of the slope with weak inclined and weak interlayer is summarized.Several failure modes of stability damage are analyzed,and the characteristics of rock mass after slope excavation and the factors affecting slope stability are analyzed.(2)Considering the high moisture content of the soft interlayer of the slope,the parameters are low,and the water content of the weak interlayer is low and the parameters are high.When the parameters of the weak interlayer are too high,the cohesive force and internal friction angle of the weak interlayer are continuously increased and corresponding calculation conditions are established.(3)The slopes are excavated when the weak interlayer parameters are low and high,and then the limit equilibrium method,elastoplastic model and strain softening model are used to calculate the stability of the slope,and the asymptotic failure characteristics of the slope are analyzed.The relationship between the safety factor of the slope is obtained:limit equilibrium method > elastoplastic model > strain softening model,and the asymptotic failure of the slope under the ideal elastoplastic and strain softening model is represented by the slope leading edge to the trailing edge.Until the slope produces a cracked surface.(4)When the parameters of the weak interlayer are high,the safety factors of the slope under different working conditions are calculated and compared by the above three calculation methods.The sensitivity of the change of the mechanical strength parameters of the weak interlayer to the stability of the slope is obtained: only Friction angle change>only the change of cohesion force;it is unreliable to evaluate the stability state of slope by traditional limit equilibrium method.It should be combinedwith the strain softening model in numerical simulation software as its stability basis,and the strain softening model is easier to calculate the slope.It shows the asymptotic failure characteristics.The length of the asymptotic damage develops further.(5)The study is in a stable state under the limit equilibrium method,but under the numerical simulation results,it is in the unstable slope.The strain softening model in the application software is used to analyze the position of the cracked surface of the slope under different shear strength of the weak interlayer.As the parameters of the weak interlayer increase,the position of the fracture surface continues to the front edge of the slope.When it is close to stability,the tensile surface moves the farthest distance,and the horizontal inclination angle of the fracture surface is greater than80°and less than 90°.