基于渗流力学的掘进工作面瓦斯涌出量预测

Prediction of gas emission volume from driving face based on seepage mechanics

为了实现煤巷掘进工作面瓦斯涌出的动态预测,基于渗流力学方法,采用瓦斯的连续性方程、运动方程、状态方程和瓦斯含量方程,建立了煤壁瓦斯渗流模型,并对渗流速度进行积分,推导得到掘进工作面的瓦斯涌出量预测公式,探讨了现场掘进过程中瓦斯涌出量预测值的准确性,在所建立的煤壁瓦斯渗流模型基础上,利用控制变量法研究了煤体渗透率和原始煤层瓦斯压力2种关键因素对瓦斯渗流速度的影响。研究结果表明:利用预测公式得到的掘进工作面瓦斯涌出量预测值与现场实际基本一致,瓦斯渗流速度随煤体渗透率、原始煤层瓦斯压力均呈负指数关系变化,煤体渗透率越高、原始煤层瓦斯压力越大,煤壁暴露时瓦斯渗流速度指数衰减越明显,随着时间增加,瓦斯渗流速度无限趋近于0。

In order to realize dynamic prediction of gas emission from seam gateway driving face, based on the seepage mechanics method, gas continuity equation, movement equation, state equation and gas content equation were applied to establish a gas seepage model of the coal wall.Integration was conducted on the seepage velocity, the prediction formula of gas emission from the driving face was deduced and obtained and the predicted value accuracy of gas emission value in the site driving process was discussed.Based on the establishment on the gas seepage model of coal wall, a controlled variate method was applied to study the two key factors on the permeability of coal and in-situ seam gas pressure affected to the gas seepage velocity.The study results showed that the predicted value of gas emission volume from the driving face obtained with the predicted formula was basic same with the site actual value, and with the seam permeability and in-situ seam gas pressure varied, the gas seepage velocity would be varied in a negative index relationship.The higher seam permeability was, the higher in-situ seam gas pressure would be.When the coal wall exposed, the gas seepage velocity index would be decayed more obviously. With time increased, the gas seepage velocity would be close to zero unlimitedly.