煤体渗透性对煤与瓦斯突出的影响规律及机制研究

The increasingly serious and complex coal and gas outburst disasters restrict the safety production of coal mine in China. Field practice shows that coal permeability is an important factor affecting coal and gas outburst. However, there is no systematic and in-depth study on this issue at present. This project will adopt the research method of combining physical simulation with theoretical analysis, taking raw coal and briquette coal as research objects. Firstly, the experimental study on coal and gas outburst induced by cross-cut coal uncovering and coal roadway excavation under different initial permeability conditions will be carried out. The mathematical expression of critical gas pressure for outburst will be obtained, and the control effect of coal permeability on outburst initiation conditions under different outburst induction modes will be discussed. Then, the influence of initial permeability on coal stress and strain, outburst strength and gas pressure under different induction modes will be analyzed. On this basis, the spatial distribution of gas pressure in coal will be obtained based on the interpolation of gas pressure data. Then, the gas release rate of outburst can be deduced and calculated by combining with the adsorption and desorption characteristics of coal. Finally, the coupling relationship among initial permeability, gas release rate and outburst strength will be studied to reveal the mechanism of the influence mechanism of coal permeability on outburst strength. The research results can establish the foundation for objective and effective identification of coal seam outburst, prediction, evaluation and prevention of coal and gas outburst.

日趋严重复杂的煤与瓦斯突出灾害制约着我国煤矿安全生产，现场实践表明，煤体渗透性是影响煤与瓦斯突出的重要因素，目前针对这一问题缺乏系统深入的研究。本项目拟采用物理模拟试验和理论分析相结合的方法，以原煤和型煤为研究对象，首先开展不同初始渗透率条件下石门揭煤和煤巷掘进诱发煤与瓦斯突出试验研究，获得突出临界瓦斯压力，并建立临界瓦斯压力与煤体初始渗透率关系式，探讨不同诱突方式下煤体渗透性对突出发动条件的控制作用；然后分析煤体初始渗透率对不同诱突方式下突出前后煤层应力应变、瓦斯压力以及突出强度的影响规律；并进一步基于瓦斯压力测点数据获取煤体内部瓦斯压力空间分布，结合煤样吸附解吸特性，推导并计算突出瓦斯释放速率；最后研究煤体初始渗透率、突出瓦斯释放速率、突出强度三者耦合关系，揭示煤体渗透性对煤与瓦斯突出强度的影响机制。研究成果可为客观、有效进行煤层突出性鉴定、煤与瓦斯突出预测、评估及防治奠定基础。

近年来煤与瓦斯突出事故频发，严重制约我国煤矿安全高效生产，突出防治刻不容缓。实践表明，煤层渗透率是影响突出的一个关键因素，突出形成的煤-瓦斯两相流不仅掩埋人员、破坏设备，还可能诱发二次灾害。首先开展了不同煤体渗透率和瓦斯压力条件下的突出物理模拟试验，分析了突出过程中煤层参数时空演化规律和突出两相流在巷道的传播致灾过程，构建了煤体渗透率和突出强度的数学关系，揭示了突出主控因素及其受渗透率影响机制。研究成果如下：1）自主搭建了一套可实现煤样一次性成型、渗透性测试和突出两相流可视化等多功能于一体的煤与瓦斯突出模拟试验系统，为开展突出物理模拟试验研究提供平台。2）突出启动后，巷道空气受压缩产生多道以正相压和负相压交替向前传播的冲击波，冲击波超压峰值在巷道中部达到最大；冲击波阵面的速度高达361.76m/s，远大于煤粉流速度，超前于煤-瓦斯流在巷道以超声速传播。3）突出发生后，煤层温度先下降后上升，和瓦斯压力演化过程具有一致性；巷道两相流温度的变化则滞后于气压的变化，呈现出短暂上升-快速下降-缓慢回升的整体演化趋势，其中煤层解吸气体吸热占据主导作用。4）当瓦斯压力从0.35MPa增加至2.0MPa时，相对突出强度由36.13%增大至63.7%；当煤层渗透率从1.38mD增加至9.10mD时，相对突出强度由78%降低至11.55%；煤层渗透率与相对突出强度呈现负指数函数关系。5）随着工作面向煤层深部推进，煤层渗透率急剧下降，瓦斯压力逐渐增加。结合试验结果得出，越是渗透率小、抗剪强度低的煤层，越容易发生突出。因此，在突出防控工作中，应尽量采取煤层卸压增透措施以提高卸压带煤层渗透率、降低工作面前方气压梯度，实现煤与瓦斯突出的有效防控。研究成果在煤与瓦斯突出预测、煤层突出危险性鉴定及煤与瓦斯突出防治方面具有广泛的应用前景。