Numerical simulation of gas migration into mining-induced fracture network in the goaf
Numerical simulation of gas migration into mining-induced fracture network in the goaf
复制标题
采空区瓦斯运移采动裂缝网络数值模拟
DOI：
10.1016/j.ijmst.2017.05.015
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发表时间：
2017-07-01
影响因子：
11.8
通讯作者：
Li Wenpu
中科院分区：
文献类型：
--
作者：
Cao Jie;Li Wenpu
中国绝大多数煤矿的瓦斯开采实践证明，在煤层上钻孔是不适宜的。相反，应该利用采空区的采动裂缝进行瓦斯开采。为研究采动裂隙中瓦斯运移，选取河南省平顶山煤矿集团10矿1个工作面为研究对象。通过建立煤层开采影响下的瓦斯运移数学模型，利用离散元软件UDEC和多物理场软件COMSOL对采空区上方采动裂隙瓦斯运移进行建模。结果表明：随着工作面推进，采空区覆岩逐渐形成采动裂隙网络，裂隙网络呈梯形，其大小随工作面推进而增大；与上覆岩基质中的瓦斯运移相比，采动裂隙网络中的瓦斯流动要大得多。最大采动裂隙位于梯形带的上端，导致网络中瓦斯通量最大。在采动裂隙区钻孔抽采瓦斯时，瓦斯抽放过程中，整个区域瓦斯浓度降低，且裂隙区瓦斯浓度下降速度较快。结果表明：瓦斯抽放后，采动裂隙网络中瓦斯流动速度加快；(C) 2017年Elsevier B.V.代表中国矿业大学出版。
Gas extraction practice has been proven for the clear majority of coal mines in China to be unfavorable using drill holes in the coal seam. Rather, mining-induced fractures in the goaf should be utilized for gas extraction. To study gas migration in mining-induced fractures, one mining face of 10th Mine in Pingdingshan Coalmine Group in Henan, China, has been selected as the case study for this work. By establishing the mathematical model of gas migration under the influence of coal seam mining, discrete element software UDEC and Multiphysics software COMSOL are employed to model gas migration in mining-induced fractures above the goaf. The results show that as the working face advances, the goaf overburden gradually forms a mining-induced fracture network in the shape of a trapezoid, the size of which increases with the distance of coal face advance. Compared with gas migration in the overburden matrix, the gas flow in the fracture network due to mining is far greater. The largest mining-induced fracture is located at the upper end of the trapezoidal zone, which results in the largest gas flux in the network. When drilling for gas extraction in a mining-induced fracture field, the gas concentration is reduced in the whole region during the process of gas drainage, and the rate of gas concentration drops faster in the fractured zone. It is shown that with gas drainage, the gas flow velocity in the mining-induced fracture network is faster. (C) 2017 Published by Elsevier B.V. on behalf of China University of Mining & Technology.