State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou, 221116, Jiangsu, China; Key Laboratory of Deep Coal Resource Mining of Ministry of Education, China University of Mining & Technology, Xuzhou, 221116, Jiangsu, China.
State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou, 221116, Jiangsu, China; Key Laboratory of Deep Coal Resource Mining of Ministry of Education, China University of Mining & Technology, Xuzhou, 221116, Jiangsu, China.
Chemosphere. 2021 Feb;264(Pt 1):128400. doi: 10.1016/j.chemosphere.2020.128400. Epub 2020 Sep 24.
Gangue backfilling mining (GBM) can effectively alleviate the gangue accumulation pollution and the overburden aquifer destruction. To efficiently evaluate the reutilization of gangue wastes by GBM and its advantage in overburden aquifer protection, non-Darcy hydraulic properties and deformation behaviors of granular gangues were studied through laboratorial, theoretical, and in-situ aspects. A series of compression and seepage tests on granular gangues under the variable original grain size grade (GSG) and stress rate were conducted. Laboratorial testing results convince that, hydraulic properties (porosity and permeability) of the granular gangue decline with the increasing original GSG and decreasing stress rate. The crushing ratio of the sample increases with the increase of original GSG and the decrease of stress rate. The fractal dimension reveals more obvious increases in the samples with the higher original GSGs and lower stress rates. The Kruger model (a classical theoretical model) was employed to predict the permeability evolution based on the porosity. However, the invalid pores in rocks would result in the model's underestimation. To this end, an improved model was established to predict the permeability evolution by the fractal dimension, and the improved Kruger model has better accuracy than the original one. Finally, according to the laboratorial testing and theoretical predicted results, friendly-environmental strategies for overburden aquifer protection were proposed. The effectiveness of these strategies was successfully verified by an in-situ application. It is concluded that the high filling stress, low gangue original GSG, and low filling stress rate in GBM can effectively reduce the risk of overburden aquifer destruction.
矸石充填采矿（GBM）可以有效地缓解矸石堆积污染和覆岩含水层破坏。为了有效地评估 GBM 对矸石废物的再利用及其在覆岩含水层保护方面的优势，从实验室、理论和现场三个方面研究了粒状矸石的非达西水力特性和变形行为。对不同原始粒径等级（GSG）和应力率下的粒状矸石进行了一系列压缩和渗流试验。实验室测试结果表明，粒状矸石的水力特性（孔隙率和渗透率）随原始 GSG 的增加和应力率的降低而降低。随着原始 GSG 的增加和应力率的降低，样品的破碎率增加。分形维数揭示了原始 GSG 较高和应力率较低的样品中更明显的增加。Kruger 模型（一种经典的理论模型）被用来基于孔隙率预测渗透率的演化。然而，岩石中的无效孔隙会导致模型低估。为此，建立了一个改进的模型，通过分形维数来预测渗透率的演化，改进的 Kruger 模型比原始模型具有更好的准确性。最后，根据实验室测试和理论预测结果，提出了保护覆岩含水层的环保策略。现场应用成功验证了这些策略的有效性。研究结果表明，GBM 中的高充填应力、低矸石原始 GSG 和低充填应力率可以有效地降低覆岩含水层破坏的风险。
