GNSS+IR Imaging for Underground Coal Mining Inducde Ground Subsidence Deformation

This paper firstly reports the combined technique of GNSS positioning and GNSS-IR (GNSS+IR) for imaging the underground coal mining induced ground subsidence deformation over an area of ~10000m² based on a single GNSS station collected observations. The GNSS positioning is utilized to measure the movements of the GNSS antenna; and phase of the reflected GNSS SNR series is utilized to calculate vertical and horizontal distance from the ground specular reflection point to the antenna. The ground subsidence and plane coordinate of the ground specular reflected point can be obtained based on the GNSS antenna movements and the vertical and horizontal distance. An analytical function is developed to describe ground subsidence around the GNSS station; the function coefficients can be estimated by using the least-squares-method to the estimations of the ground subsidence and plane coordinate at the ground reflection points. After obtaining the coefficients, subsidence deformation around the GNSS station can be imaged based on the analytical function. The preliminary results show that there is a good agreement between the proposed method based results and the reference data sets, with the RMSE less than 5cm when the in-situ ground subsidence is in the range from 0cm to 300cm.