新密矿区低临界值瓦斯动力现象及机理

Low-threshold coal and gas outburst dynamic phenomenon and mechanism in Xinmi coal mining area

本文从区域构造演化及构造特征、"三软"煤层(顶、底板和煤层均破碎的煤层及组合)分布及瓦斯特性和构造煤瓦斯内能释放等方面探讨了新密矿区低临界值瓦斯动力现象发生的机理及地质控制作用。研究结果表明:新密矿区构造演化具有多期叠加改造的性质,中、新生代拉张裂陷环境中形成的重力滑动构造对"三软"煤层的普遍发育具有重要控制作用,"三软"煤层的形成及组合形式影响井田瓦斯赋存和构造应力环境的非均衡性;顺煤层断层、煤层流变的规模及构造煤的发育程度是低临界值瓦斯动力发生的主控因素;高应力环境下"三软"煤层中构造煤的初期内能释放是激发低临界值瓦斯动力现象发生的关键;对低临界值瓦斯动力区域的预测可以通过对煤层流变和瓦斯初期解吸能的研究来实现。

The mechanism and geological control of the low-threshold coal and gas outburst dynamic phenomenon in Xinmi coalfield were investigated from regional tectonic evolution, structural characteristics, “three soft” coal seam, gas occurrence and the gas desorption ability at initial stage. Our investigation revealed that the tectonic evolution of Xinmi coalfield was reformed by multistage tectonic activities, the “three soft” coal seam was wide-spread in the whole coalfield and controlled by gravitation gliding structure which was developed in exten-sional-chiasmic environment since Meso-Cenozoic. At the same time, the combined styles of “three soft” coal seam in gravitation gliding structure influences the gas occurrence and tectonic stress heterogeneous distribution; the scale and intension of coal-seam faults and rheology, and the development of tectonically deformed coal are the controlling factors of low-threshold coal and gas outburst dynamic phenomenon; the internal energy release of tec-tonically deformed coal in high stress environment is the key to low-threshold coal and gas outburst; the low-threshold coal and gas outburst area can be predicted by studying the rheology of coal seam and the early stage of gas desorption ability.