Monitoring of residual subsidence in old goafs based on ultrashort-baseline InSAR technology

摘要

When applying the differential interferometric synthetic aperture radar (D-InSAR) technology to high-resolution SAR data, an external digital elevation model (DEM) with comparable resolution is usually not available for removing topography-related phase component for the purpose of deformation extraction. To avoid the problem due to insufficient DEM resolution, a DEMfree InSAR approach based on ultrashort spatial baselines (USB) is introduced here, capable of overcoming DEM limitations of conventional differential InSAR technique. We analyzed the principle of selection of USB interferometric pairs, and briefed permanent scatter (PS) pixel phase modelling and parameter estimation with respect to USB technology. This method was applied to the subsidence monitoring in three old goafs in Yulin mining, Shaanxi. The corresponding law of subsidence obtained was used to establish the empirical relation between circulating peak of subsidence velocity and mining thickness as well as between subsidence velocity cycle and ratio of mining depth to mining thickness. The experiment results provide basis for predicting and evaluating the residual subsidence of old goafs.