Research On The Original Terrain Restoration Method Of Loess Ancient Landslide And Its Application

The Loess Plateau is located in the north-south seismic belt of my country and the seismic belt on the northern margin of the Qinghai-Tibet Plateau.The geological structure is complex,neotectonic movement is active,seismic activity is frequent,strong earthquakes frequently occur,and huge geological disasters develop.Historical seismic data show that all previous major earthquakes in the loess area have induced a large number of loess earthquake landslides,causing heavy casualties and economic losses.Carrying out research on loess earthquake landslides will help reduce earthquake disasters in the loess area,and has important theoretical and practical significance for accelerating the urbanization process of the loess area and the in-depth development of the "Belt and Road" initiative.Due to climatic reasons,the landslides formed by these historical earthquakes have retained relatively complete landslide geomorphology,providing valuable field data for loess earthquake landslide research.The inability to obtain the topographic data of these landslides before sliding has brought certain difficulties to the study of loess earthquake landslides.Restoring the original topography of ancient landslides is the basis for studying ancient loess earthquake landslides.Therefore,the research on the restoration method of the original topography of ancient loess landslides is a hot topic in the current loess earthquake landslide research,which has received extensive attention from the academic community.Based on the existing terrain data of ancient landslides,based on the principle of equal volume of the landslide before and after sliding,this paper proposes a method for restoring the original terrain of ancient loess landslides using techniques such as three-dimensional surface interpolation.The natural slope slope and the landslide stability calculation results verify the rationality of the original terrain restoration results of the landslide.The main work completed and the research results obtained are as follows:1.Analyzed the landform characteristics of loess,and calculated the distribution law of slope and aspectAnalyzed and summarized the landform characteristics of the three loess plateau,Liang,and Gao.According to the landform characteristics of the loess plateau,Liang,and Gao,600 sets of data of the loess plateau were collected using 91 Satellite Map Assistant software.Among them,the Yuan and Liang 200 groups for each.By using the 3D Analyst function of Arc GIS software,the slope and aspect of 600 sets of loess landform data are extracted and statistically analyzed,and the respective slope distribution range and aspect distribution characteristics of the loess plateau,beam and ridge are given.2.The terrain data of the landslide was collected,and the terrain elements of the landslide were determinedTaking the No.1 landslide formed in the Pangou Formation,Sanhe Village,Xiji County,Ningxia in 1920 by the Haiyuan 8.5 mega-earthquake as an example,the back wall of the landslide,the landslide body,and the landslide were collected at a certain sampling interval using 91 Satellite Map Assistant software.Topographic data of the basic elements of the landslide such as the trailing edge.On this basis,combined with the experience of the landslide field investigation,it is proposed to use the line connecting the bottom positions of the two side walls of the landslide to determine the position of the landslide shear outlet,and to determine the position of the landslide shear outlet according to the boundary line formed by the landslide shear outlet,the trailing edge of the landslide,and the landslide two side walls.The closed boundary of the landslide determines the original perimeter of the landslide.At the same time,combined with the existing terrain sampling point data of the landslide,the position of the sliding surface is determined using techniques such as cubic spline interpolation and three-dimensional surface interpolation;on the basis of the known sliding surface,combined with the existing landslide terrain data,a landslide is proposed.Method for fast estimation of body volume.3.A method for restoring the original topography of ancient loess landslides is proposed.On the basis of the landslide terrain data,based on the principle that the volume of the landslide body should be equal before and after the slide,a method and technology such as spline function interpolation and three-dimensional surface interpolation on the MATLAB software platform are proposed to restore the original terrain of the ancient loess landslide..This method is used to complete the restoration of the original topography of the No.1 landslide in Pangou Group,Sanhe Village.According to the location of the loess morphology unit where the landslide is located,the slope distribution range of the loess plateau,beam and ridge is used to evaluate the rationality of the restoration results Initial verification and scope control.4.An example is used to verify the rationality of the terrain restoration method in this paper.According to the restoration results of the original topography of No.1 landslide in Pangou Group,Sanhe Village,a corresponding slope calculation model was established,and its stability was analyzed by numerical simulation using Geostudio software.In the process of analysis,the SIGMA/W,SLOPE/W,and QUAKE/W modules of the software were used to analyze the static stability and dynamic stability of the slope respectively.The analysis result of the stability of the landslide verifies the rationality of the recovery method.This paper also uses the pseudo-static analysis method to invert the minimum horizontal ground motion peak of slope instability.