Prediction of 3D deformation due to large gradient mining subsidence based on InSAR and constraints of IDPIM model

摘要

After underground coal resources are mined out in mining areas, large-gradient deformation is prone to occur on the ground surface during a short period of time. When the deformation gradient exceeds the threshold value of the gradient monitored by the D-InSAR (Differential Interferometry Synthetic Aperture Radar) technology, the conventional D-InSAR technology is likely to cause the failure of InSAR (Interferometry Synthetic Aperture Radar) phase unwrapping algorithms. In this case, neither the conventional D-InSAR technology nor the method of prior model + InSAR can obtain the 3D (three-dimensional) deformation field of mining-induced subsidence. Aiming at these problems, a method of monitoring 3D deformation of mining subsidence with large gradient was developed in this paper, which combines the improved dynamic prediction model and a single pair of D-InSAR. The probability integral method was firstly improved, and its problem of fast convergence at the edge of the subsidence basin was solved. Secondly, according to the geometric projection relationship between the LOS (Light Of Sight) deformation of D-InSAR in the mining area and the 3D surface deformation, the observation condition equation of the mining subsidence monitored by D-InSAR based on the improved dynamic model of PIM (Probability Integral Method) was established. Then, the solving model of prediction parameters of the improved dynamic model of PIM was constructed according to the GA (Genetic Algorithm) theory. Finally, based on the LOS deformation obtained by D-InSAR technology, the 3D deformation of mining subsidence is obtained by the 3D deformation predicting method proposed in this paper. The feasibility of the method was verified by the simulation experiment results. The LOS deformation at the edge of the subsidence basin was obtained by the differential interference processing of data from two images of Sentinel-1A on 16 November 2017 and 10 December 2017 of 1613 working face of Guqiao South Mine. The 3D deformation of the surface in the mining area during this period were obtained by using the method proposed in this paper. The predicted subsidence value was compared with the measured surface subsidence value. The result is as follow: the maximum error value of subsidence was 60 mm, about 9.1% of the maximum value of subsidence, and the fitting error of mean square of subsidence was +/- 26.21 mm. The results show that the predicting 3D deformation method of D-InSAR for large gradient of mining subsidence based on constraints of improved dynamic prediction model proposed in this paper has certain engineering application values.