| China is a country where natural disasters are frequent,and landslides,as one of the major natural disasters in mountainous areas,often cause great losses and some even devastating disasters to people’s lives and properties,and the risk evaluation of landslide hazards is the basis for carrying out landslide geological disaster prevention and control.In this paper,with Chongren Town,Shengzhou City,Zhejiang Province as the research background,based on the collection of geological and hydrogeological data of the study area,the distribution characteristics of landslide geological hazards in the study area were analyzed through field investigation,and the slope units in the whole area were mainly located in the volcanic clastic rock area,basalt platform area and the"red layer"with purple-red sandstone and sand conglomerate of Chaochuan Formation as the bedrock"The slopes in the basalt plateau area are dominated by near-horizontal laminated and blocky rocks,and the slopes in the red-layered hilly area are controlled by laminae and have relatively more types.Nine factors such as slope,geotechnical structure and slope structure were selected as evaluation factors,and a random forest model was used to construct a training set with a ratio of 1:3 between some disaster point samples and some non-hazard point samples by combining the undersampling method,and multiple undersampling was performed to construct multiple sample sets for multiple random forest training,and the most accurate set of results was selected as the final model for landslide susceptibility evaluation.Combined with the landslide formation pattern in the study area,the typical engineering geological models of the corresponding areas were constructed by using the landslide hazard characteristics of different areas in the study area.Using Geo Studio software,the stability of each model under rainfall conditions was simulated and analyzed,and the stability coefficients were transformed into the instability probability of the slope body,and the hazard evaluation zoning was carried out by combining the instability probability with the results of susceptibility evaluation.Based on the investigation and analysis of economic factors such as road distribution,building type ratio,building story ratio and floor area within each slope unit in the study area,the economic susceptibility evaluation of the study area was carried out by combining them with the disaster resistance of buildings and roads,and the population susceptibility of the study area was calculated using the population density and building use ratio;the population susceptibility and economic susceptibility of the study area were combined as the overall susceptibility The product of hazard and susceptibility obtained in the previous paper was used as the final risk factor of each slope unit by using the definition of landslide hazard risk to carry out the landslide risk evaluation.The main conclusions are as follows:(1)Precipitation is an important factor to induce landslide disaster in this area,medium and large landslides are triggered by precipitation;the influence of human engineering activities is mainly reflected in the damage caused by different forms of slope cutting on the stability of the slope.(2)Highly susceptible units are generally distributed in the front edge of basalt terraces and red layer hills in the east-central part of Chongren Town.(3)The stability of each slope decreases under rainfall conditions,and the front edge of the basalt terrace is the most unstable and has the highest risk factor.(4)The areas of very high risk,high risk,medium risk and low risk zones are8.87km~2,15.01km~2,26.91km~2 and 10.37km~2.the existing landslide hazard sample sites are basically above high risk,and only two are located in medium risk zones. |
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