Mechanism And Dynamic Evolution Of Seismic Sliding Flow On Loess Slope

Seismic sliding flow of loess slope is a kind of geotechnical earthquake disaster,which has the characteristics of low slope angle,long sliding distance,strong concealment and heavy disaster.Loess is widely distributed in China.In the loess plateau area,the strong earthquakes occur frequently.It is easy to induce sliding flow and cause significant casualties and economic losses.With the development of social and economic construction in loess plateau area,the loess seismic disaster has attracted much attention,and the problem of loess seismic sliding flow has become one of the hot issues in the field of geotechnical engineering.Exploring the formation mechanism and dynamic evolution process of seismic sliding flow has important theoretical significance and engineering application value for enriching the seismic theory of geotechnical engineering,ensuring the safety of construction projects and reducing the loss of seismic disasters.On the basis of summarizing the existing research results and field investigation,the morphological characteristics and distribution of loess seismic landslide in Haiyuan earthquake was summarized in this paper.The engineering geological survey was carried out on the site which was first discovered and named ’ Xinzhuang sliding flow ’in this paper.The evidence of sliding flow was given,and the site conditions,flow slip morphology and kinematics characteristics of the sliding flow were summarized.The influence of ground motion and site conditions on Xinzhuang sliding flow was discussed by numerical simulation method,and the formation mechanism of Xinzhuang sliding flow was explored.On the basis of three-dimensional slope modeling,the sliding process of Xinzhuang sliding flow is simulated by continuous-discontinuous method,and the estimation method of maximum sliding distance of loess seismic sliding flow was given.In this paper,the sliding flow mechanism and dynamic evolution process of loess slope under earthquake were studied.The main work and research results are summarized as follows:1.The research progress on seismic sliding flow of loess was summarized and reviewed,the problems and difficulties in this research field were discussed,and the further research work in this field was proposed.The disaster cases of seismic sliding flow of loess were collected and sorted out,and the research progress on three formation mechanisms and numerical simulation of seismic sliding flow was discussed and reviewed.2.On the basis of field investigation,the characteristics of loess seismic landslide in Haiyuan earthquake were statistically analyzed and the distribution law of loess seismic landslide was summarized,which laid the foundation for the study of loess seismic sliding flow.In this paper,the detailed survey data of 620 large-scale loess seismic landslides were used,supplemented by 605 large-scale loess seismic landslides interpreted by satellite.The characteristics of landslide parameters such as length,width,area,slope angle,epicentral distance and distribution elevation of loess landslides induced by Haiyuan earthquake were counted,and the distribution law of seismic landslides was summarized.3.Xinzhuang sliding flow was found for the first time,which has important academic value in the field of loess seismic sliding flow.Haiyuan earthquake formed a large number of loess seismic landslides in loess area,but the loess seismic sliding flow phenomenon is relatively rare.In the field investigation of Haiyuan earthquake landslide disaster,the author found a new loess seismic sliding flow phenomenon in Xinzhuang Village,Jiucai Township,Haiyuan County,and named it ’ Xinzhuang sliding flow,’.This discovery provides an excellent base for the study of loess seismic sliding flow.In this paper,a detailed field investigation was carried out on Xinzhuang sliding flow,and the basis for liquefaction of Xinzhuang sliding flow was demonstrated,which provides abundant basic data for the study of loess seismic sliding flow.4.The numerical simulation method was used to study the influence of ground motion,site conditions and other factors on loess seismic sliding flow,and the genetic mechanism of Xinzhuang sliding flow was given.Through numerical simulation,this paper analyzes and discusses the influence of ground motion intensity,frequency spectrum,duration and direction on the formation of seismic sliding flow of loess.At the same time,the influence of site conditions such as topography,stratum structure and groundwater on seismic sliding flow of loess was explored.On the basis of comprehensive analysis,the genetic mechanism of seismic sliding flow of loess was explained.5.On the basis of three-dimensional slope modeling,the sliding evolution process of Xinzhuang sliding flow was simulated by inputting specific ground motion and using continuous-discontinuous calculation method,and the estimation method of loess seismic sliding flow distance was given.In this paper,the three-dimensional terrain data of Xinzhuang sliding flow area were obtained by RTK measurement technology.On this basis,the three-dimensional slope model was established,and the model parameters and boundary conditions were determined.By inputting the seismic motion time history,the sliding process of Xinzhuang sliding flow under earthquake was simulated and the sliding distance is calculated,which is of great significance to disaster prevention and mitigation in loess area.