Analysis Of Gravel Slope Stability Under Rainfall And Earthquake

Studing on slope stability is still a hot research topic in the field of geotechnicalengineering, which also is a complex and not very good solved technical problems. Slopestability is subjected to many factors, such as rainfall, earthquake, artificial excavation, loads,soil engineering properties, etc. But among these factors the rainfall and earthquake are moreimportant and common, and which still are the focus problem in the study of slope stability.So, the analysis of the relationship between the slope and rainfall or earthquake plays a veryimportant role for prevention and treatment of the slope instability.According to the research for slope stability with rainfall or earthquake condition andsome unresolved issues, the three-dimensional numerical model of Loufangshan gravellandslide is established by FLAC3D,which is used to analyze the effect and failure mechanismof gravel soil slope stability under rainfall and earthquake.The primary contents are listed asfollows:(1) The slope safety coefficients with the conditions of single factor variation byFLAC3Dstrength reduction FEM for a homogeneous slope are calculated, and the degree ofeach influencing factor on slope stability are analyzed by using sensitivity analysismethod.The result of influence degrees is internal friction angle of slope> slope angle>cohesion> soil density.(2) The distributions of stress, displacement, plastic zone and shear strain increment ofslope under rainfall action are analyzed by the FLAC3Dnumerical calculation model ofLoufangshan landslide. The failure mechanism of slope under rainfall action is studied. Theresults show that, under rainfall conditions, the gravel soil slope stability decreases slowlyfirst and then decreases sharply with moisture’s increment,and with the critical characteristicsthat the moisture content of11.3%is the critical point of the changes in slope stability.(3) The distributions of stress, displacement, plastic zone and shear strain increment ofslope under earthquake action are analyzed by the FLAC3Dnumerical calculation model ofLoufangshan landslide. The failure mechanism of slope under earthquake action is studied.The results show that,the gravel soil slope is stable under slight earthquake loading conditions,and the degree of slope failure increases with increasing the seismic horizontal acceleration.Gravel soil slope is mainly compression failure under earthquake, but there is a small tensilestress area on the top of the slope, where is the tension failure. In the bottom of the gravel soilslope,the soil is shear failure because of the direction of principal stress has changed and soilis in biaxial compression.(4) The distributions of stress, displacement, plastic zone and shear strain increment ofslope under rainfall and earthquake joint actions are analyzed by the FLAC3Dnumerical calculation model of Loufangshan landslide, and further study is conducted on the failuremechanism of slope under rainfall and earthquake joint actions. The results indicates that thestability of gravel soil slope is lower under rainfall and earthquake joint actions than underearthquake or rainfall alone. The stability of gravel soil slope is gradually reduced with theincrease of seismic loading in the case of the moisture content remains the same. The stabilityof gravel soil slope is gradually reduced with the increase of the moisture in the case of theearthquake acceleration remains the same.Though analyzing the failure mechanism of Loufangshan gravel landslide under rainfallor earthquake action or rainfall and earthquake joint actions, the thesis presents the failuremode and failure development process of gravel soil slope, showing the characteristics ofstability of the gravel soil slope under rainfall or earthquake action, so as to provide moreapplicable experience to the prevention and remediation of slope failure.