Study On Genetic Mechanism And Stability Of Dahu Landslide In Jiefang Village,Changbai Town,Jilin Province

Landslide is a common and serious geological disaster.With the influence of economic development and natural environmental factors,the problem of landslide disaster is increasing day by day.In order to strengthen disaster prevention and control,avoid or reduce the threat of landslide damage to people's lives and property to the greatest extent,it is urgent to study the cause mechanism and stability of landslide,and then formulate reasonable prevention and control measures.In view of this,this paper takes the Dahu landslide in Jiefang village,Changbai town as the research object,comprehensively uses geophysical exploration and drilling to find out the basic characteristics of the landslide,analyzes the influencing factors inducing landslide failure,establishes the genetic mechanism model of Dahu landslide,and evaluates the stability of the landslide by using limit equilibrium method and numerical simulation technology.The spatial position of the potential sliding surface is explored by using high-density electrical method and multi-channel transient surface wave method,and the material composition and structural form of the landslide are clarified.The unstable perimeter of the landslide is defined by combining the high-density electrical method section with the drilling data.The low resistance abnormal area with the electrical layer resistance less than 130?·m corresponds to the position of the sliding body.The high resistance area reflects that the rock mass is relatively complete,and it is inferred that the average depth of the potential sliding surface is 10?15m.The contour map of multi-channel transient surface wave method and drilling results can stratify the rock and soil mass in the landslide area: the surface wave velocity of shallow loose stratum is less than 850m/s,which is the landslide accumulation layer;The wave velocity of deep hard stratum is greater than 900m/s,which is a relatively dense bedrock layer;It is inferred that the sliding zone is at the transition position between low-speed layer and high-speed layer,and the depth is about 6?18m.The lithology of weathered limestone and tuff bearing stratum is divided into gravelly soil and gravelly soil.Among them,the silty gravel constitutes the landslide mass,and the potential sliding surface is located at the foundation overburden interface between the silty gravel layer and the gravelly clay and weathered tuff.Combined with the basic characteristics of Dahu landslide,the main factors inducing landslide damage are discussed from both internal and external aspects,the formation mechanism of landslide is analyzed,and the conceptual model is extracted,which provides a reference for the research of other similar landslides.The specific genetic mechanism of landslide is that artificial activities make the front edge of the slope free,and then form tension cracks at the rear edge of the slope.The role of rainwater infiltration and groundwater increases the weight of the slope,and the shear strength of rock and soil at the foundation overburden interface decreases sharply,forming a potential sliding surface,resulting in the increase of sliding force and stress accumulation,which eventually leads to the instability of the slope and the formation of landslide.The evolution process can be divided into three stages: landslide creep deformation,slope crack development and landslide instability failure.The stability of landslide is evaluated based on the limit equilibrium theory.The stability coefficient is 1.234?1.664 under natural conditions and 0.947?1.303 under rainstorm conditions by using Lizheng geotechnical software;With the help of numerical simulation and FLAC3 D calculation,the safety factor is 1.309?1.727 under natural conditions and 1.020?1.363 under rainstorm conditions.The comprehensive analysis shows that the Dahu landslide is in a stable state in the natural state and in an unstable to unstable state in the rainstorm state.The loss caused by landslide damage can be reduced to the greatest extent through the stability evaluation of landslide disaster,which is of great engineering significance.