Using SBAS-InSAR to Detect Surface Movement above Old Mining Areas after Mine Closure

The impact of underground coal mining on the surface is not only manifested in the period of coal mining, but also after the coal mining stops and after the coal mine closes down, there will still be residual settlement, or the opposite movement - surface uplift. With the continuous development of microwave earth observation technology, time series InSAR technology has become one of the important means of surface deformation observation in mining areas. In this paper, SBAS-InSAR technology is applied to study the surface deformation movement in Lingzi coal mine, Shandong Province. The time series observations of Sentinel-1A/B data acquired from March 2015 to August 2019 were analyzed, it is found that the seasonal variation of atmosphere is more obvious under the short revisit period and long time series of satellite data, especially in mountainous areas. Considering this effect, the polynomial method is used to fit the observed results. The results show that the surface deformation in Lingzi coal mine is diverse. Some areas continue to uplift, with the maximum uplift of 69mm. Others first subsidence and then uplift, with the maximum subsidence of - 80mm. The process of subsidence and uplift is based on different mechanisms. The subsidence is the residual subsidence of underground caving caused by coal mining, and the process of uplift is related to the recharge of groundwater.