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针对富含节理裂隙的煤层瓦斯抽采钻孔结构失稳的延迟现象,分析了瓦斯抽采钻孔周边的瓦斯流场和节理裂隙场。研究表明钻孔结构失稳是由瓦斯孔隙压力和节理裂隙共同影响的;瓦斯孔隙压力的变化会影响节理裂隙表面的正应力,增加节理裂隙发育、扩展、破坏的可能性,宏观表现为钻孔结构的失稳;瓦斯抽采钻孔结构失稳时间上的延迟效应内因是由于煤层节理裂隙的存在,外因则是煤层节理裂隙中瓦斯孔隙压力的变化。最后结合实例说明瓦斯抽采钻孔结构延迟失稳能造成瓦斯抽采浓度、抽采流量的大幅度下降等问题。
In view of the delay phenomenon of the gas-in-hole structure instability in coal seam with coal-rich joints and fissures, the gas flow field and the joint fissure field around the gas drainage borehole are analyzed. The results show that the instability of the borehole structure is affected by both the gas pore pressure and the joint and fracture. The change of gas pore pressure will affect the normal stress of the joint and fracture surface and increase the possibility of development, expansion and destruction of the joint and fracture. The instability of the structure; the reason of the delay effect on the instability time of gas drainage borehole structure is due to the existence of coal seam joint fissures, and the external factor is the change of gas pore pressure in coal seam joint fissures. Finally, an example is given to illustrate the problems such as the concentration of gas drainage and drastic reduction of drainage flow caused by the delay instability of gas drainage borehole structure.