Failure Probability Analysis And Stability Study Of Gantang Landslide In Shaoguan,Guangdong

Rainfall-type landslides are representative of various types of geological disasters.They have the characteristics of wide range of damage,high speed and high degree of damage,and their own and secondary effects,which will pose a major threat to people's lives and property.It is complex and difficult to accurately analyze the influence of rainfall on the stability of landslides,and thus need to be resolved as soon as possible.Therefore,it is necessary and significant to study the rainfall-type landslides.In order to better determine the failure probability and stability of rainfall-type landslides,this paper takes the Gantang landslide in Shaoguan,Guangdong as the research object,and analyzes the environmental geological conditions and its basic characteristics.To further evaluate the stability of the Gantang landslide,the failure probability analysis method is used to calculate the failure probability and stability coefficient of the landslide,the FLAC^3Dnumerical simulation is used to analyze the changes in the landslide stress,strain and plastic zone,and the Geo-Studio numerical simulation is used to study the infiltration process of rainfall and the influence of rainfall factors on the landslide.The following research results were obtained:(1)Gantang landslide is a shallow,medium and small rock and soil landslide.The landslide landslide rock and soil are relatively broken with poor mechanical properties.The landslide is mainly controlled by the geographic and geomorphic conditions,the type of rock and soil,geological structure,rainfall and human activities.Rainfall is the main inducing factor for the Gantang landslide.The analysis of the cause mechanism of the landslide shows that the landslide has gone through the creeping stage and is in the tearing-expansion stage.(2)The research results of the failure probability analysis method showed that the Gantang landslide has a stability coefficient of 1.106?1.114 in its natural state,which is basically stable,and the failure probability ranges from 31.3%to 37.1%and belongs to belongs to medium degree.The stability coefficient on the condition of heavy rain is1.026?1.038 and belongs to the unstable status,and the damage probability ranges from51.6%to 55.3%,which is at a medium to high risk level.Compared with considering the coefficient of variation and asymmetry coefficient of the geotechnical parameter,the probability of landslide failure without considering them is relatively higher,which is more in line with engineering reality.(3)FLAC^3D numerical simulation analysis results show that the stability coefficient of the natural landslide is 1.112,which is a basic stable state,whereas the landslide stability coefficient under the heavy rain state is 1.025,which is an under-stable state.Geo-Studio numerical simulation results further show that the rainfall duration has a greater impact on the change of the stability coefficient of the landslide in the early stage.The longer the rainfall duration,the greater the landslide stability coefficient decreases with the increasing of the landslide saturation.In addition,the greater the rainfall intensity,the shorter the time to reach the basic saturation state for the rock and soil masses,the faster the landslide stability coefficient decreases,and the easier it is to lose stability in a shorter time.The study also indicated that the maximum shear stress appears on the contact surface of the weathered residual layer and the strongly weathered carbonaceous mudstone,and this contact surface can be gradually connected to form a sliding surface and slip failure occurs on the condition of the continuing rain.When the surface soil of the landslide slides,a shallow tear groove will be formed,and the rainfall infiltration will cause the landslide to evolve into a sliding rock landslide.