Study And Evaluation Of Ground Collapse In A Coal Mine Area Of Leshan City Based On SBAS-InSAR

Underground mining of coal mine is easy to cause underground mining and instability of overlying rock and soil,which leads to serious ground deformation and even serious ground collapse near coal mine area.In the past,the study of coal mine surface collapse was mainly based on surface investigation,which was time-consuming and laborious;In addition,the influence factor analysis of ground collapse monitoring based on space technology is still insufficient.Based on this,this paper takes a coal mining area in the middle of Minjiang River in Leshan city as the research area,the sentinel-1A satellite data,POD data and DEM data were selected to carry out ground collapse monitoring based on sbas-ins AR technology;combined with eight influencing factors,such as stratum lithology,distance from fault,elevation,slope,distance from river,land use,annual mining amount of coal mine and coal mining height,the weight size of factor is analyzed by using deterministic coefficient,multi-factor superposition calculation weight method and AHP;based on the deterministic coefficient model and the deterministic coefficient logistic regression model,the vulnerability evaluation of ground collapse was carried out and the vulnerability grades of regional ground collapse were divided.The main achievements are as follows:(1)The distribution characteristics and deformation characteristics of ground collapse in the study area are clarified.The subsidence monitoring results of Sbas-INSAR show that the average annual deformation rate in the study area is-3.75mm/a,and the whole area is in the trend of subsidence.The small area with large subsidence rate is mainly located near the coal mine rights in the north of the study area,and the large area with small subsidence rate is mainly located in the mountainous landform in the south of the study area.The overall deformation trend shows that the area of landform subsidence is gradually reduced from most of the southern mountains to the northern hills.The vertical average annual rate standard deviation was analyzed,and the standard deviation was mainly concentrated in 0mm-4mm,indicating the reliability of the experimental data and the reliability of the ground collapse monitoring results based on sbas-ins AR technology in the study area.(2)The influencing factors and main controlling factors of ground collapse in the study area are clarified.Based on deterministic coefficient,multi-factor weight calculation method and ANALYTIC hierarchy process(AHP),weight calculation is carried out for eight factors affecting ground collapse,including stratum lithology,distance from fault,elevation,slope,distance from river,land use,annual mining amount of coal mine and coal mining height.The corresponding weight values of each factor are:-4.650%,1.915%,3.152%,7.094%,-0.902%,10.821%,2.067%,80.503%,among which the weight of coal mining height is the highest,indicating that this factor is the primary reason affecting the development of ground collapse in the study area.The consistency index value of the factor weight results in this study is 0.000<0.1,which meets the test.(3)Construct the evaluation model of the vulnerability of ground collapse and carry out the model demonstration application.Based on the deterministic coefficient model and the deterministic coefficient logistic regression model,the evaluation results obtained by the two models were basically consistent in spatial distribution,showing a trend of decreasing susceptibility from the high susceptibility area to both sides.In general,the terrain of the study area gradually decreases to the northeast,and the vulnerability also gradually decreases,indicating that the geological environment conditions of the study area gradually improve from south to north.The frequency ratio and ROC curve were used to verify the accuracy of the evaluation results of the two models.The sum of the frequency ratios of the high-susceptibility area and the high-susceptibility area of the two models were 2.96 and 3.08,and the AUC values were 0.711 and 0.721,respectively.The verification results showed that the evaluation results of the two models could be effectively evaluated and analyzed,and the evaluation results were of high accuracy.To sum up,this paper demonstrates the spatial development law of land subsidence in the study area,quantitatively analyzes many factors affecting land subsidence and main controlling factors,and builds a division model with regional adaptability.For the local government and relevant management departments to carry out geological disaster prevention and later optimization adjustment to provide relevant support for coal development and utilization layout,it can also provide a powerful coal mine disaster prevention and control of the basic data support.