Long-term ground multi-level deformation fusion and analysis based on a combination of deformation prior fusion model and OTD-InSAR for longwall mining activity

Abstract

Abstract Caused by the underground longwall mining activities, ground deformation, which includes sudden large-level deformation, slow small-level deformation and the middle-level deformation between them, can lead to serious construction damage and ecological environment degradation. In this paper, we propose a new fusion model that is able to completely retrieve multi-level deformation with measured radar line-of-sight (LOS) deformation from offset-tracking (OT) and differential interferometric synthetic aperture radar (DInSAR) technique (referred to as OTD-InSAR). The results from OTD-InSAR show that small-level deformation on the edge of subsidence basin and large-level deformation in the central portion of subsidence basin are measured with high accuracy. The multi-level deformation fusion model considers the geographic information and SAR data information simultaneously to fuse large-level and small-level deformation and use inverse distance weighting method (IDW) to estimate the middle-level deformation. Due to the insufficient measured data in the actual situation, we present the prediction model to forecast the long period deformation evolution of full workface based on the exponent Knothe model and the fusion results. The 52,303 workface in Daliuta coal mining area in China was selected to verify the effectiveness of the fusion model and prediction model. The comparison between the fusion results and the in-situ measured data shows that the root mean square error (RMSE) is less than 0.23 m. Results of deformation prediction model are found to be very close to fusion results and the RMSE is less than 0.027 m. This research work has brought about a comprehensive analysis of the deformation evolution of the full workface with high precision from the beginning to the end of coal mining for about 18 months. As a result, the monitoring results can support the requirements of mining deformation monitoring in the management of surface disaster.