Analysis Of Ground Subsidence Monitoring In Mining Areas Using InSAR With Parameter Inversion

Because of constraints in site conditions, most coal mines are underground mines. Excessive exploitation can destroy local environments, cause hazards such as ground subsidence and surface water encroachment and endanger workers’ lives, resulting in great losses to local people and the country. However, most coal-mining firms in the country use only simple manual measurement techniques to monitor ground surface deformation, which is often ineffective and cannot monitor effects on surface vegetation, water development, mountain steep terrain and farmland subsidence, and even cannot get the trends of deformations in the process of mining and disaster forecasting information. This study focuses on how to monitor land surface changes efficiently in the process of coal-mining in the real time.The thesis focuses on a monitoring analysis method that combines Interferometrtric Snyhtetie Apertuer Radar (InSAR) and a dislocation modeling. The small baseline subset (SBAS) approach is used to monitor ground deformation. The method can effectively overcome effect of decorrelation and enhance the accuracy of D-InSAR. A simplified dislocation model for vertical displacement is studied and the geodetic inversion method is used for the coal mine studied based on the InSAR deformation results to invert the mechanism of the coal mine deformation.The thesis contains the following main research components:1) Obtaining the temporal settlement sequence of Feng-Cheng coal mine based SBAS technology. After getting a PALSAR dataset of the Ping-Hu coal mine in Fengcheng City, Jiangxi Province, D-InSAR method is used to generate interferograms based on the method of optimal fusion and linear direction windows. The deformation field for different time intervals from2007to2008are exacted. After getting seven PALSAR images of the coal mine from2007to2008, the SBAS method is used to to estimate the accumulated settlements of the high coherent points to obtain the temporal settlement sequence. Leveling results are used to verify the deformation rates and accumulated settlements from the SBAS method.2) Temporal-spatial deformation evolution of the surface deformation on mining area based on InSAR results. InSAR and leveling results are combined to analyze the temporal-spatial evolution of surface deformation in coal mining area and to predict surface deformation by deformation-time curve. The spatial surface deformation evolution of the coal mining area is analyzed based on the mining map and surface macroscopical deformation to determine the surface deformation of the working face.3) Studying the simplified rectangular dislocation model. Based on the Okada rectangular dislocation model, a simplified rectangular dislocation model is established according to the characteristics of the coal mine’s deformation and mining activities. The simplified rectangular dislocation model isused to invert the dislocation tensor to simulate the surface settlement of the mining area.4) Inversion of the dislocation tensor in the mining area. Based on the simplified rectangular dislocation model and leveling data, the linear inversion algorithm-least squares and nonlinear inversion algorithm-Monte Carlo are used respectively to invertthe dislocation tensor to obtain the collapse trend of the mining area.5) Simulation by the simplified rectangular dislocation model. According to accumulated settlement of about one year in the settlement funnels B and D of the mining area and the simplified rectangular dislocation model, the linear inversion algorithm-least squares and nonlinear inversion algorithm-Monte Carlo are used respectively to invert the dislocation tensors of the mining areato simulate the surface settlement of the mining area. It is shown that the simulation results are consistent with the surface settlement measured by SBAS method. Then SBAS monitoring data inversion and level momtoring data inversion were analyzed, and coal mining processes are analyzed based on the parameter inversion. The experimental results show that:Using the dislocation model of combining SBAS inversion of coal mine surface deformation monitoring technology is feasible.