Study On Stability Of Large-scale Slope Synthesis Under Complex Geological Environment

Slope is a common geological body in nature and human engineering activities,which widely exists in highway construction,large and medium-sized bridge construction,and mountain tunnel construction in China.With the development and construction of mountainous areas in Yunnan,the excavation and disturbance of mountain slopes are more and more intense.In this process,the problem of slope instability and failure follows,and the stability of slope becomes more and more important.Slope stability evaluation is the basic work of slope monitoring,early warning,prevention,treatment and other projects,which is of great significance to ensure the smooth construction of the project and protect people’s life and property safety.Therefore,based on the engineering background of the Yuxi bank slope complex of the Lvjujiang Bridge on the Yuchu Expressway in Yunnan Province,this paper has identified the basic geological characteristics,development mechanism,and deformation mode of the slope through on-site investigation,data collection,and indoor experiments.It has focused on the study of the sliding surface and calculation parameters of the slope,and made a comprehensive evaluation of the stability of the slope complex.The specific content is as follows:(1)Based on the analysis of the slope investigation report and other data,combined with the actual situation of site exploration,the geological environment conditions and basic characteristics of the slope were expounded.The present scale,development process and deformation mechanism of the slope were studied deeply.(2)According to the geological exploration data of the slope,the occurrence of rock strata and joint fracture of the slope were analyzed,and the location of the sliding surface(zone)of the slope complex was determined by the methods of borehole exposure and stereo-projection analysis.(3)The shear strength parameters of the slope body were obtained by in-situ test,laboratory soil test and engineering geology analogy method.And on the basis of monitoring displacement,the inverse optimization method of strength reduction and displacement analysis was used to invert the shear strength parameter values that are more close to the slope displacement changes.The final strength parameter values of the slope were obtained by combining the above methods.(4)The transfer coefficient method based on the limit equilibrium theory,Midas GTS NX finite element method and FLAC3 D finite difference method were used to analyze the slope stability from multiple angles,such as safety factor,displacement and stress,and the slope stability was evaluated comprehensively by combining the Analytic Hierarchy Process(AHP)-Matter Element Extension Model.The calculated results were compared with the numerical simulation results.The reliability was verified.According to the stability evaluation results,it was concluded that the overall Yuxi bank slope complex of Lvshuijiang Bridge was basically stable.The upslope of the tunnel was stable in natural condition and basically stable in rainstorm condition.The right side slope was stable in natural condition and understable in rainstorm condition.