Analysis of Pre- and Post-Mine Closure Surface Deformations in Western Xuzhou Coalfield From 2006 to 2018

Economic development and population expansion in mining cities have led to a growing scarcity of land for construction and thus the closed mines land reuse is extremely urgent. Exploration of the law of surface deformation in closed mine is therefore significance for the development of mining cities. In this study, we first used the StaMSBAS technique to reveal surface deformation of western Xuzhou coalfield from 16/6/2006 to 19/8/2018, based on 77 SAR images. The result of ALOS-1 monitoring was validated by levelling data, and it was shown that the root-mean-square-error and standard deviation were 31.8 mm and 28.9 mm, respectively. The law of surface deformation that occurred before and after mine closure was finally analysed. It was found that: 1) After mine closure, the surface deformation of Jiahe mine experienced the process of subsidence, relative stability and then uplift, and the surface deformations of Zhangxiaolou and Pangzhuang mines changed from slow subsidence to accelerated subsidence. 2) Where the maximum pre-closure subsidence occurred at Jiahe mine, the residual subsidence and uplift that occurred after mine closure was also significant, the correlation coefficients were 0.62 and 0.65, respectively. When the mines were active, surface subsidence of Jiahe and Zhangxiaolou mines was positively correlated with the strike mining degree, with correlation coefficients of 0.90 and 0.83, respectively. After Jiahe mine closure, the residual subsidence was positively correlated with the strike mining degree, and the surface uplift was positively correlated with the depth-to-thickness ratio, the correlation coefficients were both 0.70.