Exploration and stability evaluation of coal mine goaf based on SBAS technology

The long-term exploitation of coal resources has led to the existence of large-scale underground goafs. The rapid development of urban construction has made land resources increasingly tense,which leads to the land in subsidized areas of coal mines become an important resource for sustainable development. The high-precision and large-area investigation of mining subsidence and the evaluation of goaf stability are conducive to alleviate the increasingly sharp contradiction between underground goaf and ground construction,and have important practical significance for the sustainable development of the city. InSAR technology can realize the inversion of surface deformation with large coverage area and millimeter level accuracy through historical images,which has obvious advantages over conventional measurement methods. In order to further explore the availability of InSAR in the investigation and stability evaluation of coal resource goafs,in this paper，the 14 Sentinel-1 images during 2018-09-12 to 2019-03-11 were used to invert the deformation time series in the Jining district with SBAS method. The spatial distribution of coal mining subsidence area was successfully identified,and the interpreted deformation accuracy also was evaluated. The results show that,① More than 10 coal mining subsidence sites in the Jining district area were detected,and the maximum medium error between the monitoring results and the measured data was 5.8 mm; the surface deformation rate of study area is mostly less than -10 mm/a,which indicates that the goaf at the corresponding location has basically stabilized. ② the deformation curves of the ground points extracted by SBAS conform to the basic law of mining subsidence,and also can distinguish the characteristics of the surface residual deformation under different mining conditions. ③ The researches of this paper not only can improve the efficiency of geological survey in coal resources goaf,but also can provide basic data for goaf stability evaluation.