Study On Temporal And Spatial Evolution Law Of Surface Residual Deformation In Coal Mining Subsidence Area

The large-scale exploitation of underground coal resources leaves a large number of mined out areas,and the resulting surface subsidence generally goes through different periods,such as initial period,active period,recession period,residual subsidence period and so on,ranging from a few months to a few years or even decades.Coal mining subsidence area as construction land is a practical problem that needs to be faced in the process of urbanization and Rural Revitalization in China,and the stability research of subsidence area is related to regional planning,infrastructure construction and scientific and rational utilization of underground space.Although some research achievements have been made in the research of residual deformation law in the previous research,it still needs to be further explored in the division of surface subsidence process,the temporal and spatial evolution law of residual deformation and dynamic prediction model.Using various research means and methods such as field measurement,theoretical analysis and In SAR satellite monitoring,this paper carried out long-time sequence deformation monitoring of Lingxin Coal Mine in Gansu Province Based on 51 scene Sentinel-1A image data from 2015 to 2017,and extracted the surface cumulative deformation field and deformation rate information of the mining area.Focusing on the051603 working face in the fifth mining area of the mine,the deformation data of the working face tendency and strike are extracted and compared with the long-term monitoring results of CORS station,which verifies the reliability of SBAS-In SAR technology in the monitoring of surface residual settlement in the mining area.The prediction model of surface residual settlement based on logistic time function is constructed.The temporal and spatial completeness of time function and the influence of model parameters on the prediction results are discussed,and the model is verified by measured data.The main work and research results of this paper are as follows:(1)Research on the law of surface deformation based on SBAS-InSAR Technology:using SARscape to solve the Sentinel-1A image data,the deformation rate and cumulative deformation field of Lingxin Coal Mine Area are obtained and analyzed.The annual average deformation rate of the mining area is-198.75mm/a～30.46mm/a.(2)Analysis of surface residual settlement process based on CORS station and SBAS-In SAR Technology: three CORS observation stations are arranged above the working face,and the information of surface residual settlement above 051603 working face is obtained through long-term settlement monitoring.SBAS-In SAR technology is used to extract the settlement information of three characteristic points on the surface above 051603 working face(the position of the characteristic points coincides with the corresponding position of CORS station)and the strike and dip profile of the working face.The characteristics and laws of settlement are analyzed and compared with the monitoring results of CORS station.Using the accuracy evaluation indexes such as correlation coefficient,maximum deviation,average absolute error and root mean square error,the feasibility of SBAS-In SAR technology in surface residual settlement monitoring is verified.(3)Research on dynamic prediction model of surface residual settlement: according to the subsidence speed of the largest subsidence point in the subsidence basin and the degree of mining damage,the surface migration process is divided into three different periods: surface movement continuation period(including initial period,active period and decline period),residual settlement period and long-term settlement period.A dynamic prediction model of surface residual settlement based on logistic time function is proposed,The inversion method of model parameters is given,the start and end time of residual settlement is derived,and the temporal and spatial completeness of time function and the evolution law of residual settlement coefficient are discussed.Finally,taking the132153 working face(insufficient mining)of Wannian mine in Fengfeng mining area and the 051603 working face(super-critical mining)of Lingxin Coal Mine in Ningxia as the engineering background,the effectiveness of the mathematical model is verified.The results show that the prediction model based on logistic time function can reflect the typical characteristics of surface subsidence,subsidence speed and acceleration in time and space.It is an ideal time function model.It plays a key role in the calculation of surface residual settlement.The surface residual settlement coefficient is directly proportional to the prediction parameters and inversely proportional to time.The amount of measured data has a significant impact on the inversion of model parameters.The inversion results of model parameters are stable and reliable only when the local surface settlement monitoring time exceeds the active period.Otherwise,there will be a large deviation between the predicted value and the measured value.