Study On The Risk Of Landslide Disasters In The Gengma-Lancang Earthquake Zon

Landslides triggered by earthquakes are an extremely common secondary hazard that can cause more serious damage than earthquakes.The study area is located in the southwestern part of Yunnan Province and belongs to the Gengma-Lancang seismic zone,a high intensity area with an earthquake intensity ofⅨdegrees.There are a number of landslides and other geological hazards developed in the study area due to various local factors.Through a systematic study of the seismic response characteristics,we can explore the geohazards in the area in a comprehensive and in-depth manner and make an accurate estimation of their associated risk levels.In addition,through systematic investigation,statistics and analysis,we can also better predict the potential risks in the area,thus better protecting the local people and potentially providing greater benefits to the local economy.Using GIS software,this study explores in detail the different seismic load frequencies and their associated amplitudes,and their effects on the dynamic feedback mechanisms of landslides;and,using a hierarchical analysis-information volume model,a complete hierarchy of landslide hazard risk intervals is established,and the results of this study can provide a reference for future prevention and control.The main research contents and results of the thesis are as follows:(1)Based on the investigation and research on the geological environment conditions,development characteristics,and spatiotemporal distribution patterns of earthquake landslide disasters in the study area,the main influencing factors of earthquake landslide disasters in the study area were analyzed.Finally,six influencing factors,namely elevation,slope,slope direction,stratigraphic lithology,distance from fault zones,and distance from water systems,were selected as the risk assessment indicators for earthquake landslides.(2)The ANSYS finite element technique can be used to effectively study and evaluate the seismic response characteristics of a single landslide,thereby ensuring its stability.To this end,the strength discount factor of the finite element can be gradually increased as a means to reduce the shear strength of the landslide,and after several experiments,the maximum damage force can eventually be obtained,thus ensuring the reliability and safety of the landslide.In the analysis of the seismic response of the landslide,the seismic load is reasonably taken according to the seismic intensity code of the region for the seismic load frequency and load amplitude,and the seismic load frequency levels are 0.50Hz,2.21Hz,5.63Hz and 10.08Hz,and the seismic load amplitude levels are 0.2m/s~2,0.5m/s~2,0.8m/s~2,1.1m/s~2 and 1.8m/s~2.The influence law of the dynamic response characteristics of the landslide under the self-weight condition and the self-weight coupled seismic load condition is analysed.The stability coefficients of the landslide under different conditions are calculated by the finite element strength reduction method,and the simulated values are compared with the limit equilibrium method to verify the effectiveness of the strength reduction method.(3)In the risk analysis of regional earthquake landslides,the risk of earthquake landslide disasters in the study area was evaluated based on six evaluation factors selected:elevation,slope,slope direction,stratigraphic lithology,distance from fault zone,and distance from water system.The risk evaluation index system of seismic landslide hazards in the study area was established by using the information quantity method,and each factor was assigned a weight by the hierarchical analysis method,and then the influence factors were weighted and superimposed by Arc GIS software to classify the risk of seismic landslide hazards in the study area into four levels:very high risk,high risk,medium risk and low risk,and the risk zoning results of seismic landslide hazards were obtained The results were obtained.