Study On Slope Stability Of Sanshenggou Tunnel Exit

Traffic projects in the western mountainous areas of Sichuan Province,such as the proposed Dujiangyan-Siguniangshan Railway and National Highway G350,often encounter various adverse geological problems such as dangerous rock masses,collapses,landslides,and mudslides during construction and operation.The slope of the slope at the exit of the Sanshenggou tunnel of the research object is relatively large,the rock formation is steep,the weathering is more serious,and there is a dangerous rock mass above the entrance of the tunnel.Qualitative analysis found that this slope has many structural surfaces,and the qualitative analysis through a single survey point is not enough to reflect the overall failure mode of the slope.Therefore,discrete element numerical simulation is needed to analyze the failure mode of the slope in order to compare and compensate for the discrete element analysis.To reflect the stress,deformation and strength evolution characteristics of the slope,dete rmine the strength failure area,etc.,and then perform the finite difference soft simulation.Considering the large surface fluctuations,it is necessary to establish a true three-dimensional slope for simulation research and comparison Shortcomings in the two-dimensional simulation.In view of this,this paper uses the slope of a proposed railway Sanshenggou tunnel as a basis for stability analysis and research.With the help of indoor uniaxial tests,qualitative analysis and field measurements,the lithology at the exit of the Sanshenggou tunnel is analyzed as metamorphic.The physical and mechanical parameters of sandstone sandwiched slate are used and various numerical simulations are carried out.（1）Firstly,the strength of the structural surface of the site is obtained through the field point load test and rebound value test of the rock sampled on site.Secondly,the uniaxial compression test of the rock can relatively objectively reflect the failure process of the rock.Through the uniaxial test,the uniaxial compression strength of the rock in the study area of Sanshenggou is 60MPa,the elastic modulus is 6.4GPa,and the Poisson’s ratio is 0.25.Using Hoek-Brown and Mohr-Coulomb’s strength standards,the compressive strength of metamorphic sandstone sandwich slate is 1.05Mpa.（2）On the basis of outdoor data,the structural plane parameters of 5 survey points on the site are studied.The deformation and failure characteristics of the slope are sliding failure along the joint plane and tensile cracking slip.It is concluded that the toe of the natural stable slope is 52.9°,and the HSMR The evaluation score is 55 points,and the failure mode of stereographic projection analysis is local sliding along the joint plane.（3）Finally,the finite difference software FLAC^3D and the discrete element software3DEC were used to simulate the natural stability conditions,rainfall conditions,and seismic load conditions of the slope at the exit of Sanshenggou.At the same time,the two-dimensional models of UDEC and FLAC^2D were compared respectively to study the influence of surface fluctuations and model boundary effects on the numerical simulation.In general,nature and rainfall have also caused damage to the surface of the slope.The damage is concentrated.The displacement has developed from centimeter to meter.Under seismic load,the slope will fail to slide along the structural surface.For the two types of software The simulations of the two methods have preliminarily proved the applicability of the two methods to the rock slopes in the study area.The finite difference simulation analysis shows that the stress,deformation and strength evolution characteristics of the slope are closer to the field measurement;the failure mode and failure area obtained by the discrete element It is consistent with the scene,so the discrete element software is more suitable for the analysis of the failure mode of rock slopes.