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为研究井下卸压抽采时瓦斯流动规律,建立煤层渗透率演化模型。为建该模型将煤体简化为有2组相互垂直节理发育的等效连续介质,假定瓦斯在煤体裂隙中的流动符合立方定律,考虑煤基质对吸附性气体的吸附膨胀作用和外荷载对煤的压缩变形作用,不考虑孔隙压力对裂隙张开的影响。从应力条件和孔隙压力2个方面,结合煤样渗透率试验,对该模型进行有效性验证。结果表明,渗透率模型能反映应力和低孔隙压力对煤样渗透率的影响,但不能体现高孔隙压力对煤样损伤导致的渗透率增大作用。
In order to study the gas flow law during underground pressure relief mining, the evolution model of coalbed permeability was established. In order to construct this model, the coal is simplified as an equivalent continuous medium with two sets of mutually perpendicular joint development. Assuming that the gas flow in the coal body fissures accords with the cubic law, the adsorption and expansion of adsorbed gas by the coal matrix and the external load The compressive deformation of coal does not consider the influence of pore pressure on the crack opening. From the aspects of stress condition and pore pressure, combined with the permeability test of coal sample, the validity of this model is validated. The results show that the permeability model can reflect the influence of stress and low pore pressure on the permeability of coal samples, but can not reflect the effect of high pore pressure on permeability increase caused by coal sample damage.