| Wanzhou District of Chongqing is located in the hinterland of the Three Gorges Reservoir Area,in which landslide disaster is the most common geological disaster in this area.Landslide disaster will cause serious damage to natural resources,human life and property,and factors such as rainfall and reservoir water level will often induce the occurrence of landslide disaster in this area.In order to reduce the harm of landslide disaster,engineering treatment measures are often taken for landslide,but most of the traditional treatment schemes are based on the safety factor in the specification,that is,the landslide is treated until it does not occur at all.Although this can minimize the occurrence of landslide disaster,from the perspective of risk management.This kind of governance concept often causes excessive governance and unreasonable resource allocation.It is unscientific and uneconomical at the level of economic benefits.Therefore,it is particularly important to fully understand the formation mechanism of landslide disasters in this area and carry out risk management research for single landslides.In this paper,the landslide disaster caused by rainfall inducement is studied,and the risk analysis and management control system for this kind of single landslide is constructed.Taking Lantianba landslide in Wanzhou District as an example,the risk analysis of landslide under five rainfall conditions is carried out,and the dynamic analysis software DAN3 D is used to analyze the movement process of landslide.Then on this basis,the vulnerability analysis of the disaster-bearing body is carried out,and the quantitative calculation of landslide disaster risk under different working conditions is completed.Four risk control schemes are proposed.Finally,the cost-benefit analysis method is used to compare the independent scheme and the combined scheme.The main research results are as follows:(1)The quantitative risk analysis and management framework of single landslide disaster suitable for rainfall inducement in Wanzhou District is proposed.(2)Taking Lantianba landslide in Wanzhou District as an example,based on geological data,field investigation results and historical deformation data.The basic shape and deformation characteristics of Lantianba landslide are obtained,and the main causes of landslide deformation are analyzed.Based on the meteorological data for many years,five rainfall conditions for the study are determined.(3)Geo-Studio finite element simulation software is used to calculate the landslide risk,and the stability under natural conditions is checked by the transfer coefficient method,which verifies the reliability of the numerical simulation results.The calculation results show that the landslide stability is positively correlated with rainfall intensity and rainfall.Under the rainfall condition of once in a hundred years,the probability of landslide failure is the largest;The DAN3 D software was used to analyze the landslide movement process.It was found that the rainfall had a negative effect on the landslide movement.In the 100-year rainfall condition,the peak velocity of the landslide movement and the maximum movement distance of the sliding body were the largest.(4)Through the analysis of the landslide movement process,the identification of the hazard bearing body and the quantitative analysis of the vulnerability of the hazard bearing body are completed.It is considered that the vulnerability of the hazard bearing body on the sliding body is 1,and the quantitative results are calculated based on the corresponding formula for the buildings and population outside the sliding body.According to the product of the risk,vulnerability and the value of the hazard bearing body,the total economic risk estimation value and the population risk value of the landslide disaster under each working condition are calculated.The economic risk is the largest under the 100-year rainfall condition,which is 829,300 yuan,and the population risk is up to 7 people.It can be seen that reducing the influence of rainfall incentives is of great significance to reduce the risk of landslide disasters.(5)In view of the disaster risk caused by Lantianba landslide,engineering and nonengineering measures are taken for risk control,and four risk control schemes are proposed.Quantitative calculation of landslide disaster risk after taking preventive measures.Among them,the risk after the implementation of anti-slide pile project is the lowest,which is about 75.6 % lower than that without treatment.After the implementation of the monitoring and early warning project,the risk is only reduced by about 5 %,but it has a significant effect on population risk control;using the costbenefit formula,the benefit cost rate of each scheme is obtained.The interception and drainage project is the best choice in the independent risk control scheme.In addition,after using the four measures to prevent and control at the same time,the residual risk of the disaster reaches the lowest,which is 99 % lower than that without treatment,which can significantly control the risk of landslide.However,considering the comprehensive economic factors,through the cost-benefit analysis,it is considered that the combination scheme of slope cutting and drainage engineering is the optimal scheme. |
