Research On The Distribution Characteristic And Rapid Evaluation Method Of Haiyuan Earthquake-induced Landslide

The 1920 Haiyuan earthquake induced a large number of loess landslide disaster,it led to heavy casualties,economic losses and ecological damage in Xiji,Haiyuan,Guyuan(referred to as the Xi Hai gu)area.Xi Hai gu area is located in the northwest of the Loess Plateau in China,the north of China's north-south seismic belt,where the geological structure is complex and intense.In this area,the earthquake is multiple and which can easily induce geological disasters.Study on the distribution,rapid assessment of seismic loess landslides in Xihaigu region have important theoretical and practical significance to promote the region and the loess area of disaster prevention and mitigation work and construction to establish the stability of loess slope method.Based on detailed field investigation,research was carried out on the distribution and stability of loess slope of the loess landslide triggered by earthquake rapid assessment methods,completed the main work and achievements are summarized as follows:1.Summarized and commented the current research situation of Haiyuan earthquake and its loess landslide.Summarized and reviewed the Haiyuan earthquake damage,loess engineering characteristic of loess landslide,classification,distribution,loess landslide influence factors and development mechanism,the evaluation of the stability of loess slope method research history and present situation.Summarized the loess landslide distribution and pointed out the purpose and significance of research on rapid evaluation of the stability of loess slope and putted forward the loess landslides are needed in the future focus on the issue.2.Summarized the regional geological environment survey and Haiyuan earthquake earthquake background of the research area.In this paper,the geological and seismic background of the study area are summarized and analyzed from six aspects: natural and social survey,regional geological structure,topography,Stratum lithology,seismic and hydrogeological characteristics.And,summarized the Haiyuan earthquake from the basic situation,the Haiyuan earthquake meizoseismal area and intensity classification,tectonic background,experience and damage and abnormal intensity in detail.3.Analysised the distribution and development characteristics of loess landslides in the study area.Based on the detailed investigation in the field,the landslide in the study area is divided into different types according to the development position of the sliding surface,the development mechanism,the scale,the thickness of the sliding body,the plane shape and the section shape.On the basis of the relationship between the distribution and intensity of the landslide,the fault distance,the extension of the loess beam and the local topography,the spatial distribution characteristics and rules.According to the original landslide slope height,slope angle and slope etc.the experimental data on the distribution of original terrain landslide;landslide based on field measured data of length,width and thickness,slope,sliding distance,volume and direction of the main slide,posterior wall height and inclination angle,profile etc.Summarizes and analyzes the characteristics of landslides.Through the actual investigation and statistical analysis,this paper argues that the landslide in the study area has the characteristics of zoning,mass,steep wall,sliding body,large scale and long distance sliding.4.This paper analyzes the influencing factors of the distribution and development of the loess landslide,and puts forward the developing mechanism of the loess landslide.Based on summarizing the research area of loess seismic landslide distribution and development characteristics,analyzed and summarized the main factors affecting the distribution of landslides in this area are topography,lithology,fault,groundwater,earthquake intensity,overburden thickness and topography.Through summing up of the research on the mechanism of loess landslide,based on the field observation of a large number of landslides and sliding surface morphogenesis,puts forward the development mechanism of Haiyuan earthquake induced loess landslide can be divided into tensile shear sliding vibration,seismic subsidence softening and shear slip,seismic subsidence and liquefaction-flow softening shear vibration liquefaction of composite slip failure.5.Given the rapid evaluation of loess slope seismic stability method.In the field investigation and remote sensing interpretation for high slope H,slope angle and intensity of A estimation based on the values of I,this paper uses logistic regression analysis method,fitting empirical formula of loess slope stability research area rapid evaluation.The results show that the formula can be applied to evaluate the seismic stability of the Loess Slope in the study area,and it has important practical significance for the earthquake emergency rescue.