Parameters Inversion Of Exponent Knothe Model Based On SAR Images

Synthetic aperture radar interferometry(InSAR)is one kind of surface deformation monitoring technologies developed in recent decades.It can obtain the surface images with all-time,all-weather,large-range and high-precision,and can extract the ground deformation induced by volcanoes,earthquakes,landslides and underground resources exploitation with high accuracy.However,mining activities not only cause small surface deformation at the edge of subsidence,but also cause large gradient surface deformation in the center of subsidence in a short time interval.When the revisit period of radar satellite is fixed and the deformation gradient during images acquisitions is larger than the gradient range measured by InSAR technology,the interference pair will be incoherent and the clear interference fringe can’t be obtained,which will affect the subsequent phase unwrapping and the accurate surface deformation information can’t be extracted.Therefore,it is difficult to extract large gradient surface deformation information with high accuracy in the mining area only by using InSAR technology.Aiming at the extraction of surface deformation information in mining areas,the research status of InSAR technology in monitoring sruface deformation,extracting large gradient subsidence and establishing three-dimensinal surface deformation model caused by mining activities at home and abroad,and the method combining InSAR technique with mining subsidence model can be proposed to extract surface deformation information induced by coal mining in this paper.The commonly used mining subsidence models are probability integral method,Knothe model and Logistic model,etc.At present,some scholars have used probability integral model and Logistic model combined with InSAR technology to estimate and predict surface deformation information caused by mining activities.Knothe model is widely used to analyze the surface subsidence process at a single point,in which is inconsistent with the actual surface subsidence process.To sum up,the method combined InSAR technology with exponent Knothe model is proposed to extract the surface deformation information caused by mining activities.The detail research contents are described as following:l)The parameters of exponent Knothe model are inverted and estimated based on InSAR technology.InSAR technique is used to extract the LOS deformation value.The functional relationship is established between the LOS deformation and the parameters of exponent Knothe model.The least square method is adopted to estimate the parameters.2)The large gradient surface deformation information caused by coal mining is predicted based on exponent Knothe model.The mining-induced subsidence prediction formulas based on exponent Knothe model are established using the model parameters obtained by InSAR technique in the previous chapter.The large gradient surface deformation is predicted and extracted on the workface.3)The three-dimensional surface deformation model casued by coal mining is constructed combined with exponent Knothe model.Based on the functional relationship between LOS deformation and three-dimensional surface deformation,the subsidence values obtained by the above-proposed exponent Knothe model are adopted to predict the horizontal deformation values along the north-south and east-west directions.Finally the three-dimensional deformation model is constructed by using the above-predicted deformation results.