Shi Zhanshan, Ye Donglin, Hao Jianfeng, Qin Bing, Li Gang
School of Mining, Liaoning Technical University, Fuxin, Liaoning 123000, China.
Liaoning Academy of Mineral Resources Development and Utilization Technical and Equipment Research Institute, Liaoning Technical University, Fuxin, Liaoning 123000, China.
ACS Omega. 2022 Jul 7;7(28):24531-24550. doi: 10.1021/acsomega.2c02255. eCollection 2022 Jul 19.
For extra-thick coal seams, slice mining is a safer mining method than top coal mining, which can effectively reduce the strong mine pressure behavior caused by mining. However, in the slice mining of high-gas and extra-thick coal seams, the gas in the lower slice flows into the goaf, which increases the gas control difficulty on the upper slice working face. It is easy to cause the gas transfinite at the upper corner in the upper slice and reduce the mining efficiency. Therefore, it is of a great significance to carry out the research on gas control technology in slice mining of the extra-thick coal seam. There are some problems in the gas control of slice mining, such as a single gas control method, low control efficiency, and unclear gas migration law. Therefore, it is necessary to study the gas migration law and propose a targeted prevention and control the technical scheme. In order to improve the gas control efficiency of the extra-thick coal seam, the evolution law of permeability of the lower slice is obtained under mining through experimental research. The liquid-solid coupling seepage-flow model for gas migration is established in the lower slice. Comsol Multiphysics software is used to study the migration law of pressure relief gas in the lower slice. Based on the gas migration law, the gas extraction and cut flow technology for the lower slice long borehole is proposed. Through this technology, the amount of gas flowing into the upper slice goaf and the gas content of the lower slice are reduced, and the drilling horizon is optimized. The research results show that the determination of the optimal drilling horizon of the lower slice needs to balance the amount of gas flowing into the goaf and the total amount of gas extraction. The range of 3-7 m horizon in the lower slice is appropriate to the boreholes arranged. When the borehole is located in the lower slice -3 m horizon, the 360 day gas emission quantity of goaf can be reduced to 51.2% of the nondrilled emission quantity, and the total extraction amount is 1143 m. When the borehole is located in the lower slice -7 m horizon, the 360 day gas emission quantity of goaf can be reduced to 95.31% of the nondrilled emission quantity, and the total extraction amount is 1461 m. Considering the gas emission capacity of the upper slice and ensuring that the total extraction volume of the lower slice is maximized and the boreholes in the lower slice are not damaged, the boreholes are located in the -6 m horizon of the lower slice.
对于特厚煤层，分层开采是一种比分层开采更安全的开采方法，它可以有效减少开采引起的强烈矿压行为。然而，在高瓦斯特厚煤层的分层开采中，下分层的瓦斯会流入采空区，这增加了上分层工作面的瓦斯治理难度。容易导致上分层上角瓦斯超限，降低开采效率。因此，开展特厚煤层分层开采瓦斯治理技术研究具有重要意义。分层开采瓦斯治理存在瓦斯治理方法单一、治理效率低、瓦斯运移规律不明确等问题。因此，有必要研究瓦斯运移规律，提出针对性的防治技术方案。为提高特厚煤层瓦斯治理效率，通过实验研究得出开采条件下下分层渗透率的演化规律。建立了下分层瓦斯运移的液固耦合渗流模型。利用Comsol Multiphysics软件研究了下分层卸压瓦斯的运移规律。基于瓦斯运移规律，提出了下分层长钻孔瓦斯抽采与截流技术。通过该技术，减少了流入上分层采空区的瓦斯量和下分层的瓦斯含量，并优化了钻孔层位。研究结果表明，下分层最优钻孔层位的确定需要平衡流入采空区的瓦斯量和瓦斯抽采总量。下分层3-7m层位范围适合布置钻孔。当钻孔位于下分层-3m层位时，采空区360天瓦斯涌出量可降至未钻孔涌出量的51.2%，总抽采量为1143m。当钻孔位于下分层-7m层位时，采空区360天瓦斯涌出量可降至未钻孔涌出量的95.31%，总抽采量为1461m。综合考虑上分层瓦斯涌出能力，在保证下分层抽采总量最大化且下分层钻孔不被破坏的前提下，钻孔位于下分层-6m层位。
