基于体积应变含瓦斯煤增透率模型及采动响应研究

Study on model of mining-enhanced permeability and mining response of gas-filled coal based on volumetric strain

为获得含瓦斯煤开采过程中渗透率的采动响应规律,从孔隙率的基本定义出发,通过引入增透率来反映单位体积改变下煤体渗透率的变化,建立了基于体积应变的含瓦斯煤增透率模型。基于增透率模型,结合工程实例采用Comsol Multiphysics模拟了含瓦斯煤开采过程中增透率的变化规律,并开展了增透率采动响应的试验研究。研究结果表明:增透率模型可对采动裂隙网络形成的煤层透气性进行定量评价研究,采动是影响含瓦斯煤增透率的关键因素,受采动影响,煤体体积应变、增透率的变化规律均基本一致,煤体膨胀变形、增透率随采煤工作面的推进逐渐增大,增透率的变化滞后于体积应变的变化,且越靠近工作面煤层增透效果和瓦斯抽采效果越好;沿煤层倾向,回风巷侧最大瓦斯抽采量大于运输巷侧,煤体增透率亦大于运输巷侧。依据增透率的采动响应规律调整瓦斯抽采孔与工作面的角度,可增加抽采量,降低工作面瓦斯浓度。

In order to obtain the mining response laws of permeability in the process of gas-filled coal mining , start-ing from the basic definition of porosity , the change of permeability of coal under the unit volume change was reflec -ted by introducing mining-enhanced permeability , the mining response model of permeability was established based on volumetric strain .The variation of mining-enhanced permeability in the process of coal mining was simulated based on the mining-enhanced permeability model by using Comsol Multiphysics , and the mining response of min-ing-enhanced permeability in the field was studied .The results showed that the coal seam permeability formed by the mining-induced fracture network can be quantitatively evaluated by the mining-enhanced permeability model . Mining is the key controlling factor affecting coal permeability , the variation of volumetric strain , mining-enhanced permeability is consistent affected by mining , the swelling deformation of coal and permeability increases gradually as the working face advancing , the mining-enhanced permeability changes lag behind the changes of volumetricstrain , and the closer to the face , the better results of mining-enhanced permeability effects and gas extraction .A-long the coal seam , the largest gas drainage , the fractured development and the extent of damage at the return air-way side seam are greater than those of haulage roadway at the same location away from the face;mining-enhanced permeability is also greater than that of haulage roadway .The gas holes are set to a certain angle with working face based on the mining response laws of mining-enhanced permeability;it can prolong the gas drainage time , increase the amount of gas drainage and prevent the gas gauge effectively .