Study On Stability And Failure Mode Of Dangerous Rock Mass In Shangmujiangping Slope

Shangmujiangping slope is located in Yingxiu Town,Wenchuan County,which is close to G350 national highway.It is planned that a railway tunnel will pass through the slope.The Shangmujiangping slope is tall and steep with complex geological conditions,including collapse,unloading cracks and dangerous rock mass,which poses a certain threat to the G350 national highway as well as the proposed railway tunnel crossing the Shangmujiangping slope.Therefore,this paper combines the field survey data and scientific method to analyze the stability of Shangmujiangping slope to safeguard the safety of highway and railway.This paper studies on Shangmujiangping slope.The slope structure characteristic information is collected by means of the detailed field geological survey.The field and laboratory tests is conducted and the test data is modified by Barton model to get the physical and mechanical parameters of rock mass.The internal friction Angle(?)is 41°.The cohesion(C)is 3.2MPa.The elastic modulus(E)is 17.6GPa.The Poisson's ratio is 0.241.On these basis,the slope stability is qualitatively analyzed by using the method of stereographic projection and HSMR.the comprehensive comparison of the qualitative analysis results shows that the failure modes of the slope are sliding-tensile fracturing and wedge sliding along the double sliding surface.The random joint model based on Monte Carlo method was established by Matlab software.The discrete joints and blocks of the model is made to be similar to the actual situation.A random joint slope model is established at the section of entrance of the railway tunnel.The model is applied to UDEC discrete element numerical simulation software to analyze the stability of the slope under natural state and seismic conditions.In natural state,the maximum displacement occurs at the top of the slope and the displacement converges.Under seismic condition,the displacement mainly occurs in the middle of the slope.The slope slides along the joint of which dip angle is small and the back edge pulls apart along the joint of which dip angle is large.These actions result in typical slip-tensile fracture and stress concentration at the toe.By comprehensively comparing the quantitative analysis of discrete element numerical simulation with the qualitative analysis of the stereographic projection method and HSMR method,the failure mode of the slope is sliding-tensile fracturing.Based on the qualitative analysis of geological method and discrete element numerical simulation analysis results,it is concluded that the Shangmujiangping slope has the possibility of instability both in the natural state and under the earthquake condition.The possibility of instability of the slope surface and top is higher.The stress concentration occurs at the toe of the slope.The failure modes of the slope are sliding-tensile fracturing and wedge sliding along single or double slip surfaces.The conclusion provides a reference for the safety construction and operation of highway and railway and offer some reference in the stability analysis of high and steep slope in western Sichuan.