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覆压−注水作用下含瓦斯煤解吸特性试验研究

Experimental study on desorption characteristics of gas-containing coal under the action of overburden pressure and water injection

  • 摘要: 深部开采易形成地应力与瓦斯的耦合作用,出现地应力主导型的煤与瓦斯突出事故。为了提高矿井瓦斯灾害防治的精准性,亟需深入了解地应力作用下水分介入后对含瓦斯煤解吸特性的影响。在试验室搭建了覆压作用下注水对煤样瓦斯解吸特性影响的模拟测试装置,通过向试验煤样施加覆压,同时注入水分,研究覆压−注水作用下含瓦斯煤的解吸特性。基于该试验装置,测试了古汉山矿(GHS)煤样在覆压5、10、15 MPa,水分0、2%、4%和6%,相同充气量条件下的瓦斯解吸数据。通过分析试验数据,得到覆压−注水作用对GHS煤样累计瓦斯解吸量、瓦斯解吸速度、初始瓦斯解吸速度影响系数和残存瓦斯含量的影响规律。研究结果表明:覆压作用使干燥煤样累计解吸量和初始瓦斯解吸速度增大,促进了瓦斯解吸;随着水分的介入,覆压大的煤样累计瓦斯解吸量和初始瓦斯解吸速度反而变小,说明水分抑制了瓦斯解吸,水分介入后覆压作用从促进瓦斯解吸过渡为抑制瓦斯解吸。理论分析认为,覆压的活塞效应促进干燥煤样的瓦斯解吸,随着水分的介入,水分在煤体裂隙和孔隙中产生了强烈的毛细管阻力,随着覆压增大,煤样被压碎压实,煤中孔隙尺寸变小,毛细管阻力变大,从而产生更强的抑制解吸作用,试验结果对于更深入认识水力化措施防治煤与瓦斯突出的机理具有一定的积极意义。

     

    Abstract: It is easy to form a coupling effect between ground stress and gas, and cause the accident of coal and gas outburst dominated by ground stress during deep mining. In order to improve the accuracy of mine gas disaster prevention, it is urgent to deeply understand the influence of water intervention on the desorption characteristics of gas-containing coal under ground stress. A simulation test device was set up for the effect of water injection on the gas desorption characteristics of coal under overburden stress and water injection by applying overburden stress and injecting water at the same time to the experimental coal sample. Based on the experimental setup, the gas desorption data of coal samples from Guhanshan Mine (GHS) were tested at overburden stresses of 5 MPa, 10 MPa and 15 MPa, moisture content of 0%, 2%, 4% and 6%, and the same inflation amount. By analyzing the experimental data, the influence of overburden stress and water injection on the cumulative gas desorption amount, gas desorption rate, initial gas desorption rate influence coefficient and residual gas content of GHS coal samples was obtained. The result shown that the overburden stress effect increased the cumulative desorption amount and the initial gas desorption rate of the dried coal samples, which promoted gas desorption. With the intervention of water, the cumulative gas desorption amount and initial gas desorption rate of coal samples with large overburden stress became smaller, indicating that the moisture inhibited gas desorption, and the overburden stress effect transitioned from promoting to inhibiting gas desorption. Theoretical analysis shown that the piston effect of overburden promoted gas desorption of dried coal sample. As moisture intervention, it produced a strong capillary resistance in the pores and cracks of coal. With the increasing overburden stress, the coal sample was crushed and compacted, and the capillary resistance became larger as the pore fissures got smaller, resulting in a stronger inhibition of desorption. The experimental results have certain positive significance for an in-deep understanding of the mechanism of hydrodynamic measures to prevent coal and gas outburst.

     

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