淮南矿区关闭矿井地表次生沉陷InSAR监测与规律分析

Monitoring and Law Analysis of Surface Secondary Subsidence of Closed Mines in Huainan Mining Area Based on InSAR

不同地质采矿条件下关闭矿井地表次生沉陷规律是国内外关注的问题之一,对此进行研究具有重要的理论和实用价值。淮南矿区地下潜水位高、第四系松散层厚、煤层开采多,监测分析淮南矿区关闭矿井地表次生沉陷规律具有典型性。基于160景Sentinel-1A数据,利用永久散射体干涉法(persistent scatterers interferometry,PSI)和小基线集(small baseline subset,SBAS)技术分别获取了2016-01-14—2022-05-30淮南矿区关闭矿井地表次生沉陷。结果表明,新集三矿、李嘴孜-新庄孜-谢一矿关闭后地表上升,新庄孜矿最大上升速率为51.1 mm/a,而潘一矿因关闭时间晚(2018-09)受采空区残余形变影响地表仍表现为下沉。由PSI和SBAS同名点监测结果统计分析可知二者相关性为0.74,标准偏差为1.59 mm/a,证明了合成孔径雷达干涉结果的可靠性。通过时序形变分析,将淮南矿区关闭矿井地表次生沉陷规律归纳为下沉阶段—稳定阶段—上升阶段,但下沉、稳定和上升阶段并不一定随时间推移逐次发生。由地表上升起始时间及李嘴孜矿、新庄孜矿和谢一矿的位置关系可知,三矿之间可能存在水力联系,地下水先从新庄孜矿和谢一矿交界处开始回升,后流向东南和西北两侧。研究成果对完善关闭矿井地表沉陷规律、构建地表沉陷预测模型具有重要意义。

Objectives:As a continuation of mining subsidence,the surface secondary subsidence(including sinking and uplift)of closed mines poses a potential threat to the safety of surface buildings-structures in mining areas.However,at this stage,the law analysis of the surface secondary subsidence of closed mines under different geological mining conditions is not yet comprehensive.Due to the high underground water level,thick Quaternary loose layers,and multiple coal seams in the Huainan mining area,monitoring and analyzing the surface secondary subsidence of closed mines in the Huainan mining area has important theoretical and practical values.Methods:First,in order to verify the reliability of the monitoring results,the StaMPS software is employed to simultaneously perform persistent scatterers interferometry and small baseline subset processing.Amplitude dispersion index and amplitude difference dispersion index are used to select coherent points,respectively.Then,the unwrapped phases of the coherent points are obtained by a three-dimensional phase unwrapping algorithm.Finally,the surface subsidence of the coherent points are obtained by using temporal-domain low-pass and spatial-domain high-pass filtering.Results:The results show that:(1)The surface uplifts after the closure of Xinjisan and Lizuizi-Xinzhuangzi-Xieyi mines,with a maximum uplift rate of 51.1 mm/a,and is located in Xinzhuangzi mine,while the surface of Panyi mine is still sinking due to its late closure in September 2018.(2)The surface secondary subsidence law of closed mines in Huainan mining area is sinking stage‑stable stage‑uplift stage,which is consistent with the surface subsidence law of closed mines in Xuzhou mining area,but the sinking,stable and uplift stages do not necessarily occur successively over time.(3)There may be a hydraulic connection between Lizuizi,Xinzhuangzi,and Xieyi mines.The groundwater first rises from the junction of Xinzhuangzi and Xieyi mines and then flows to the southeast and northwest sides.Conclusions:Although the law of surface subsidence in the closed mines of Huainan and Xuzhou mines is relatively consistent,there are differences in the law of surface uplift due to different hydrogeological mining conditions.Therefore,in future work,we will continue to pay attention to the law of surface secondary subsidence of closed mines under different geological mining conditions.