煤层采掘过程瓦斯流动耦合模拟研究

发布时间：2018-05-15 17:38

本文选题：煤层采掘过程 + 结构变形　；参考：《山东科技大学》2017年硕士论文

【摘要】：煤层采掘过程容易引发煤与瓦斯突出等严重自然灾害。在前人研究成就基础上,本文深入研究了煤层采掘过程中的煤体结构变形与煤层瓦斯流动间的耦合特征,这对于正确掌握煤层采掘过程可能引发的瓦斯突出规律,对于减少、预测和防治瓦斯灾害事故等,均具有重要意义。本文首先简述了煤层采掘过程引发的煤体结构变形特征以及瓦斯在变形煤体内的渗流流动特征;在此基础上,建立了煤体结构变形应力场与瓦斯流动渗流场之间的多场耦合数学模型;利用大型仿真模拟软件,模拟得出了煤层采掘过程中煤体结构应力场、瓦斯流动渗流场相互耦合的煤体应力、瓦斯压力、位移与瓦斯流速的分布特征与分布规律。最后,利用模型算例进行了验证分析。算例验证结果表明,本文所建立的多物场耦合模型是合理的,模拟计算结果与现场实际情况符合程度高,结果具有满意的可信度。本文第4章的煤层采掘过程细观瓦斯流动多物场耦合模拟结果表明:(1)在煤巷掘进过程中的不同时段,煤体结构变形的应力值先是在巷帮两侧出现了具有对称特征的卸压低压区,两侧向里则相似呈现应力集中峰值,然后垂向应力逐渐随距煤壁距离的增大而减小,并在煤层深部趋于稳定;(2)瓦斯压力则可受到煤层初始瓦斯压力、煤层渗透率、煤体变形应力的共同作用与影响,且随距煤壁的距离呈现非线性分布,并最终在煤层深部趋于稳定;(3)瓦斯渗流速度随距离采掘面距离的变化而变化,且同一点的流速在不同时刻又受地应力、瓦斯压力的显著耦合影响。本文第5章的算例模拟分析结果表明:(1)煤层掘进工作面开采位置延伸后,由于应力状态不同和透气性的差异,初采切眼附近的瓦斯压力降低很快;随着工作面的延伸,瓦斯压力呈动态变化,最后趋于一个固定值。(2)煤层初采切眼附近的瓦斯压力梯度,在切眼周围存在明显的瓦斯压力梯度分布,且随煤层的开采、瓦斯的卸压,其瓦斯压力梯度分布范围逐渐扩大。(3)本算例的验证结果表明,本文所建立的多物场耦合模型是合理的,模拟计算结果与现场实际情况符合、结论可信。
[Abstract]:Coal seam excavation process is prone to lead to coal and gas outburst and other serious natural disasters. On the basis of previous research achievements, this paper deeply studies the coupling characteristics between coal structure deformation and coal seam gas flow in the process of coal seam mining, which is helpful to correctly grasp the law of gas outburst that may be caused by coal seam mining process, and to reduce the gas outburst in coal seam mining process. It is of great significance to predict and prevent gas disasters and accidents. In this paper, the characteristics of coal structure deformation caused by coal seam excavation and the seepage flow characteristics of gas in the deformed coal body are briefly introduced, and on this basis, The coupling mathematical model between the deformation stress field of coal structure and the seepage field of gas flow is established, and the stress field of coal structure in the process of coal seam mining is simulated by using large-scale simulation software. The distribution characteristics and law of coal body stress, gas pressure, displacement and gas velocity of gas flow seepage field. Finally, a model example is used to verify and analyze the model. The simulation results show that the coupling model is reasonable, and the simulation results are in good agreement with the actual situation, and the results have satisfactory reliability. In chapter 4 of this paper, the simulation results of mesoscopic gas flow and multi-field coupling in coal seam mining show that the stress value of coal structure deformation first appears symmetrical pressure relief low pressure area on both sides of roadway in different period of time during coal roadway tunneling. The vertical stress decreases gradually with the increase of the distance from the coal wall, and tends to stabilize at the depth of the coal seam. The gas pressure can be subjected to the initial gas pressure of the coal seam and the permeability of the coal seam. The coaction and influence of deformation stress of coal body show nonlinear distribution with the distance from coal wall, and finally tend to stabilize in the deep coal seam) the velocity of gas seepage varies with the distance of mining face. The velocity at the same point is influenced by the coupling of ground stress and gas pressure at different time. The simulation results of the fifth chapter of this paper show that the gas pressure near the initial cut decreases rapidly due to the difference of stress state and gas permeability after the mining position extension of the coal seam driving face, and with the extension of the coal face, The gas pressure changes dynamically and tends to be a fixed value. Finally, the gas pressure gradient near the initial cut hole in the coal seam tends to be a fixed value. There is obvious gas pressure gradient distribution around the cut hole, and with the coal seam mining, the gas pressure is released. The verification result of this example shows that the coupling model of multi-matter field established in this paper is reasonable, and the simulation results are consistent with the actual situation and the conclusion is credible.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712

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