| The mountainous region of southern Shaanxi has a complex geological structure,with weak metamorphic rock layers such as schist,slate,and phyllite widely distributed.The climate is complex and changeable,with high rainfall frequency and high intensity,which can easily induce major geological disasters such as landslides.In recent years,the number of rainfall-type landslide disasters in southern Shaanxi has remained high,causing large losses to people's lives and property.It has become a significant stumbling block to southern Shaanxi's social and economic development,as well as a significant geological and environmental issue.The data of a huge amount of rainfall and landslides in southern Shaanxi is counted in this paper.Based on the geographical and climatic characteristics of southern Shaanxi,the temporal and spatial relationships between rainfall and landslide disasters are summarized.The eleven groups of landslides in Yangjiawan are used as the model,and the finite element method is used to study the landslides in different rainfall scenarios.The reliability analysis theory is used to analyze and evaluate the risk of landslides using the change of body seepage field.On this basis,the critical rainfall of rainfall-type landslides in southern Shaanxi was studied,an early warning and forecasting model based on landslide probability was established,and a case of landslide disasters induced by heavy rainfall in southern Shaanxi on July 16,2010,was tested.The results show that the forecast effect is good.The main research results are as follows:1)The rainfall characteristics and landslide characteristics in southern Shaanxi are summarized using a mathematical-statistical analysis of rainfall conditions and landslide data:rainfall in southern Shaanxi is mainly concentrated in the rainy season(June to September),mostly in the form of heavy rain and continuous rain The frequency of landslides is unevenly distributed throughout the year.The number and scale of landslides are temporally and spatially correlated with rainfall.The rainy season is a season where landslides occur frequently,and landslides usually occur on the day or the second day of heavy rainfall.2)Using the Geo-studio finite element software SLOPE/W,SEEP/W,SIGMA/W in conjunction with the 11th group of Yangjiawan landslides as an example,the changes in pore water pressure and soil moisture content under various rainfall scenarios were discussed.The influence of rainfall on the stability of landslides is studied using law and the Monte Carlo method.3)Using SPSS software to analyze the rainfall and landslide data in southern Shaanxi,the rainfall intensity-diachronic expressions in southern Shaanxi and some counties and cities were obtained,as well as the threshold relationship between the previous rainfall and the current day's rainfall,and the maximum hourly rainfall of the day.4)The logistic regression model of rainfall-induced landslides in southern Shaanxi was obtained through SPSS software,and the software was tested for goodness of fit.The accuracy rate was 87.5%through the test of historical landslide data in southern Shaanxi.Hourly rainfall is a method for evaluating the risk of slopes.The effective cumulative rainfall calculation method was obtained through SPSS software,and the effective rainfall landslide probability prediction model was established,with the model being revised to account for the impact of short-term heavy rainfall.The model was verified by historical landslide data in southern Shaanxi.After the revision,the accuracy of the forecast has been improved.5)A landslide early warning and forecasting method was developed using the landslide probability prediction model.Taking the heavy rainfall event in southern Shaanxi on July 16,2010,as a representative,the early warning and forecasting of landslide disasters in Dazhuyuan Town,Hanzhong City,and Langao County was carried out.From the results,The model's forecast of the actual occurrence of landslide disasters in Dazhuyuan Township(high probability)is at least 4 hours earlier than the actual occurrence of disasters,and the forecast of landslide disasters in Liulin Village and Langaba Village,Tielu Township,Langao County(high probability)at least 22 hours in advance,and the forecast for the landslide disaster in Muzhu Village,Siji Township,Langao County(high probability)is advanced at least 7 hours,indicating that it is possible to accurately predict rainfall-induced landslide disasters. |
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