A large gradient deformation monitoring method for mining areas based on unscented Kalman filter sparse phase unwrapping

The time series interferometric synthetic aperture radar （InSAR） technique based on the stable point targets is an important means of wide-area and high-precision surface deformation monitoring in mining areas at present. However, InSAR sparse phase unwrapping still faces the challenges of low unwrapping accuracy and poor reliability in areas with large gradient deformations in mining areas, which seriously restricts the accuracy of surface deformation monitoring in mining areas. To address these problems, a large gradient deformation monitoring method for mining areas based on unscented Kalman filter sparse phase unwrapping is proposed, and analysis of surface large gradient deformation monitoring in Kouzidong Mine Areas is carried out. This method considers the complex sparsity of interferometric phase and constructs a Kriging sparse interferometric phase grid interpolation strategy based on von Karman autocovariance function. Combined with the unscented Kalman filter phase unwrapping technique, an unscented Kalman filter sparse phase unwrapping method based on the Kriging interpolation is then proposed to achieve accurate interpretation of large gradient surface deformation in Kouzidong Mine Areas. The experimental results show that the proposed method can effectively recover the deformation phase information at large gradient changes in the mining area, which have higher unwrapping accuracy and reliability than traditional sparse phase unwrapping methods. And the proposed method has only a root mean square error of about 14 mm compared with similar time period leveling data, which shows the relatively highest deformation monitoring accuracy. Additionally, the deformation field in the Kouzidong Mine Areas is approximately distributed along the 140502 working face, and the maximum subsidence in the satellite radar line of sight within 36 days is as high as 135 mm. The research results provide an effective technical solution for high-precision monitoring of large gradient surface deformation in mining areas, and can provide important data basis for geological disaster control and prevention in mining areas.