突出发动过程中煤岩-瓦斯系统能量失衡致灾机制研究

Coal and gas outburst is serious in China, and becomes more severe as the mining depth increase. In recent years outburst prevention technique is developing rapidly, while the outburst mechanism research as the guide is relatively backward. The outburst mechanism research needs turn to quantitative study from qualitative understanding. Through experiment and theory analysis, this project would study the effect of coal mass damage in the outburst launch process on outburst energy accumulation and the energy bearing capacity of coal and gas system. Firstly, through the test of gas desorption and sound emission in the whole stress-strain process of coal, the effect of coal mass damage on coal matrix gas desorption would be analyzed. And then considering the effect of coal mass damage, the formula of coal mass elastic energy and desorption gas expansion energy is established, and combining the evolution model of coal and gas before outburst, the evolution of outburst energy before outburst initiation is studied. Finally, through the physical simulation experiment of coal and gas outburst with different conditions of mechanical and gas loading, the maximum energy of coal and gas system could be determined by the result whether or not outburst occurs. And the effect of coal mass damage on energy carrying capacity of coal and gas system could be studied, and then the action mechanism of energy unbalance of coal and gas system in outburst initiation would be uncovered. This project is beneficial for the quantitative and modeling of coal and gas outburst, and could provide the fundamental basis for outburst prevention work development.

我国煤与瓦斯突出灾害严重，并随着采深的增加日益严峻。近年来防突技术在快速发展，而作为理论指导的突出机理研究相对落后。突出机理研究需要由定性化认识向定量化研究转变。本项目采用实验和理论分析相结合，对突出发动过程中煤体损伤对煤岩-瓦斯系统突出能量积聚与可承受能力的影响进行研究。首先通过煤岩全应力应变过程中瓦斯解吸及声发射实验，确定煤岩损伤裂隙扩展对基质瓦斯释放能力影响规律。然后建立考虑煤体损伤影响的煤体弹性能、解吸瓦斯膨胀能计算公式，结合构建的突出发动前期煤岩-瓦斯演化模型，确定突出前期煤体损伤破坏过程中煤岩-瓦斯系统突出潜能演化规律。最后通过不同力学、瓦斯加载条件下突出模拟实验，由突出是否发生确定煤岩-瓦斯系统可承受的最大能量，研究煤体损伤对系统能量承载能力的作用规律，进而揭示煤岩-瓦斯系统能量失衡致灾机制。项目的开展将有利于突出机理的定量化、模型化，为煤矿防突工作的发展提供理论基础。

瓦斯灾害是限制我国煤矿安全高效开采的主要因素之一，特别是随着采深增加煤与瓦斯突出灾害愈加显著。近年来突出防治技术的发展和煤矿安全需求的增强都对煤与瓦斯突出机理研究提出了更高的要求。本文基于双重孔隙介质模型建立了煤与瓦斯突出发动之前煤岩—瓦斯演化控制方程，分析煤岩损伤对突出能量演化影响。由于煤岩损伤、解吸环境压力变化，在突出发动时其向外释放的条件并非一成不变。经化简分析后，提出了考虑煤岩损伤和非常压解吸环境的解吸瓦斯膨胀能计算公式，与之前瓦斯膨胀能计算不同。煤岩损伤对瓦斯能量作用的数值分析表明，损伤裂隙发育会影响基质瓦斯扩散能力，从而对突出发动时膨胀功产生显著影响，在工作面前方创造一个瓦斯膨胀潜能高峰带，是突出危险的发动区；突出发动时尽管处于正压环境，但是环境压力在与大气压条件下未有几倍悬殊条件下，对瓦斯能影响较小，可视作常压下解吸；瓦斯赋存及流动条件是影响瓦斯分布，因此对瓦斯膨胀能影响显著，而煤体受力条件主要作用是对弹性能起决定作用。从而得到了突出前期煤岩损伤对煤岩-瓦斯系统能量及抗失稳能力作用机制，确定了采动应力对突出的影响，解释了构造煤突出危险性高的原因，能够为煤与瓦斯突出预测及消突机理提供理论指导。此外，根据基质尺寸对瓦斯释放能力作用规律，结合采煤工作面前方卸压带内承载地应力卸荷，煤体有损伤裂隙发育的特点，提出利用卸压带裂隙发育的特点，采用水平长钻孔对随采随冒的极近距离邻近层进行提前预抽和边采边抽，得到工程应用。