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为揭示低渗透性煤层瓦斯抽采渗流机制,在综合考虑Klinkenberg效应、有效应力和解吸收缩对瓦斯渗流及煤体变形影响的基础上,建立描述瓦斯渗流及煤骨架可变形的流固耦合模型。运用该模型,优化某矿29031工作面本煤层顺层钻孔的抽采负压和钻孔间距。结果表明,在抽采钻孔附近,模型考虑Klinkenberg效应比未考虑Klinbenberg效应时瓦斯压力下降更快,距离抽采钻孔越远,Klinkenberg效应的影响越小;在抽采时间一定的前提下,抽采负压对煤层瓦斯压力的下降影响不明显,有效抽采半径与抽采负压之间满足幂函数关系;考虑现场的复杂性和不均衡性,需要增加30%的安全余量,29031工作面本煤层顺层钻孔间距为6 m时,瓦斯压力下降幅度及范围最大,同时可以有效地避免“空白带”和抽采的无效叠加,抽采效果比较理想。
In order to reveal the seepage mechanism of gas drainage in low permeability coal seam, a fluid-solid coupling model describing gas seepage and deformation of coal skeleton is established based on comprehensive consideration of Klinkenberg effect, effective stress and desorption shrinkage on gas seepage and deformation of coal. The model is used to optimize the suction pressure and borehole spacing of the coal seam in the coal seam 29011 working face. The results show that the model considers the Klinkenberg effect to drop faster than the Klinbenberg effect without considering the Klinkenberg effect and the farther away from the drilled hole, the smaller the Klinkenberg effect is. When the extraction time is constant, The negative pressure of pumping has no obvious effect on the decrease of coal gas pressure. The effective power extraction radius and pumping negative pressure satisfy the power function relationship. Considering the complexity and unevenness of the site, it needs to increase 30% safety margin. 29031 When the distance between layers is 6 m, the pressure drop and the range of the gas pressure are the largest. At the same time, the ineffective superposition of “blank belt” and extraction can be effectively avoided, and the pumping effect is ideal.