Miao Kaijun, Tu Shihao, Wang Yuyao, Li Jinghua, Zhao Hongbin, Guo Benhuan
School of Mines, China University of Mining and Technology, Xuzhou 221116, China; State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
School of Mines, China University of Mining and Technology, Xuzhou 221116, China; State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
Sci Total Environ. 2023 Dec 10;903:166812. doi: 10.1016/j.scitotenv.2023.166812. Epub 2023 Sep 4.
Coal mining-induced groundwater losses may trigger water inrush disasters and surface ecological degradation. The compaction and seepage characteristics of broken rock in gobs can be used to find the balance point of water inrush prevention and water resource protection in shallow coal seam groups. These characteristics, as well as geological and engineering parameters of shallow coal seam mining, are experimentally determined in this study. The performed permeability tests revealed that the percentage of voids in broken rock exponentially decreased with the axial stress. The water seepage of broken rock in the compaction process conformed to the Forchheimer theory, with the permeability ranging from 10 to 10 D. The initial value and reduction range of mudstone permeability in the three lithologic samples were the smallest. The uniaxial compression strength reduction caused by the increase in unit mass water due to water saturation of natural rock samples were 5.8 and 3.2 % for coal and sandstone, respectively. Based on the experimental results on compaction and seepage of broken rock, the axial stress-percentage of voids-permeability model considering compaction and re-crushing was established. The mudstone roof was found to be the key rock stratum during re-mining for ecological protection and hydraulic connection evaluation of the overburden.
煤炭开采引起的地下水流失可能引发突水灾害和地表生态退化。采空区破碎岩石的压实和渗流特性可用于寻找浅煤层群突水防治与水资源保护的平衡点。本研究通过实验测定了这些特性以及浅煤层开采的地质和工程参数。所进行的渗透率测试表明，破碎岩石中的孔隙率随轴向应力呈指数下降。破碎岩石在压实过程中的渗流符合福希海默理论，渗透率范围为10至10达西。三种岩性样品中泥岩渗透率的初始值和降低幅度最小。天然岩石样品因水饱和导致单位质量水增加而引起的单轴抗压强度降低，煤和砂岩分别为5.8%和3.2%。基于破碎岩石压实和渗流的实验结果，建立了考虑压实和再破碎的轴向应力-孔隙率-渗透率模型。发现泥岩顶板是复采过程中覆岩生态保护和水力联系评价的关键岩层。
