The Study On Risk Assessment Of Ground Subsidence In Renhe Coal Mine Concentration Area Of Panzhihua City Based On InSAR Time Series Analysis Technology

Concentrated mining activities in coal mines often lead to cave-in and ground subsidence hazard.The ground subsidence hazard is mainly manifested as surface collapse pits and linear ground cracks on the surface,damaging the surface buildings,roads and underground facilities,causing the groundwater level to drop,damaging natural resources and harming to people's lives and the safety of life and so on.Therefore,it is necessary to monitor ground subsidence in coal mine.In the previous study,traditional techniques such as Global Positioning System(GPS),Global Navigation Satellite System(GNSS),Leveling measurement,etc.Traditional techniques were high cost,low precision,low efficiency,limited coverage,affected by weather conditions and discontinuous observation,which made it difficult to implement accurate monitoring.In Renhe coal mine concentration area of Panzhihua city in Sichuan province,SW China,has a long history of coal mining,with frequent cave-in disasters and ground subsidence widely outcropping.However,there is still lack of real-time monitoring data,which led to serious threats and dangers around the mining area.In view of the above shortcomings,the concentratation area of Renhe coal mine was selected as the research area in this paper,and the ground subsidence monitoring technology of the InSAR time series analysis technology was explored to obtain the detailed subsidence information based on the thirty-one time-series sentinel-1A satellite datas.By this way,this paper revealed the spatial and temporal distribution characteristics of the ground subsidence in the study area.Meanwhile,the factors affecting land subsidence were analyzed in combination with relevant data such as geological background data.Then the risk evaluation system of land subsidence was established,and the demonstration application of ground subsidence risk evaluation was carried out.The main achievements are as follows:(1)Explored of InSAR time series analysis technology for ground subsidence monitoring in the study area.The two kinds of InSAR timing analysis technologies,that is,SBAS-InSAR and PS-InSAR,were carried out using the image data of 31 scenes Sentinel-1A which obtained from April 2017 to October 2019.The experimental results showed that the SBAS-InSAR technology is more suitable and efficient for ground subsidence monitoring in the concentrattion areas of coal mines.(2)Revealed the time and space distribution characteristics of ground subsidence.? The ground subsidences in the study area are mainly distributed in Taiping coal mine area,Huashan coal mine area,Dabaoding coal and Xiaobaoding coal mine area and other large and medium-sized coal mine areas,and in the Artemisia Branches of Xiaobaoding coal mine bay and Moyu bay area and the north part of Huashan coal sludge of well-known regional land subsidence phenomenon is relatively serious,main show is settlement extents of degree bigger,deeper;?The ground subsidences in the study area has the temporal evolution characteristics of spatial transfer,that is,with the passage of time,new ground subsidence areas are constantly emerging in different mining areas,and the ground subsidence scope and degree are constantly expanding and deepening(3)Explored the influence factors of ground subsidence,and constructed the risk evaluation index system of ground subsidence based on fuzzy analytic hierarchy process Firstly,the relationships between ground subsidence and formation lithology,fault,groundwater type,precipitation,slope,slope direction,mine development area type and mine wellhead(adit head)were explored,and the factors affecting ground subsidence in the study area are analyzed.Secondly,on this basis to determine the target layer 1,layer 3 conditions and 10 factor layer,the system of land subsidence risk assessment in the study area is constructed;Finally,based on the fuzzy analytic hierarchy process to determine the weight of each evaluation factor,the evaluation factor target are:the land subsidence rate(0.1589),ground subsidence cumulant(0.13),formation lithology(0.0744),fracture(0.0894),groundwater type(0.0644),slope(0.0796),slope direction(0.0604),rainfall(0.0597),mine development area type(0.144)and wellhead(adit head)position(0.1393)(4)Based on the comprehensive evaluation method,this paper carries out the application research on the risk evaluation of ground subsidence in the research area,divides the prevention and control areas of ground subsidence,and puts forward the corresponding prevention and control countermeasures.Based on the risk assessment results,this paper divides the study zones into five regions:extremely high risk,high risk,medium risk,low risk and very low risk.Four prevention and control zones are divided into the key prevention and control zones,the secondary key control zones,the general control zones and the focus zones.According to the different types of prevention and control areas,the Suggestions of relocation,warning,avoidance,timely management and regular monitoring and management are put forward.