深部煤与瓦斯共采中的优质瓦斯通道及其构建方法

High quality gas channel and its construction method applied to coal and gas simultaneous extraction in deep mining

瓦斯抽采钻孔围岩的破坏形态和范围对于瓦斯通道区域的联通具有重要影响。以钻孔围岩"蝶形塑性区"理论模型为基础,对深部煤与瓦斯共采中钻孔瓦斯导向通道进行了研究,结果表明:深部环境和采矿活动引起的"加载"与"卸荷"效应,会使钻孔围岩出现有利于瓦斯导通的"蝶形塑性区",蝶叶长度可达钻孔直径的几十倍以上。以"蝶形塑性区"理论为基础,提出了优质瓦斯通道的概念:通过协调采矿工程活动与瓦斯抽采钻孔布局,形成有利于瓦斯抽采的瓦斯导通和流动网络;并确定了以构建优质瓦斯通道的应力环境,确定钻孔布置岩层层位及协调采矿活动与钻孔时空关系为主要内容的优质瓦斯通道构建方法,以实现优质瓦斯通道的高效性、稳定性、长期性,提高瓦斯抽采效率。

Currently borehole extraction is a main engineering measure in coal and gas simultaneous extraction. The destruction pattern and range of drilling surrounding rock have a great influence on the link of gas channel area. In order to rationally design drilling gas guide channel for deep coal and gas simultaneous extraction and promote the guided flow,a theoretical model of drilling surrounding rock plastic zone was established. The model shows that:in deep mining environment influenced by mining unloading,a large-scale deviatoric stress area is formed in the coal and rock mass of mining space,and under the effect of high deviatoric stress,the butterfly damage zone,which is advantageous to the gas conduction,appears in the borehole surrounding rock. The butterfly zone length can reach more than dozens of times of borehole diameter. Based on the butterfly plastic zone theory,the concept of high quality gas channel was put forward,which means by coordinating mining engineering activities and gas drainage borehole layout,the gas conduction and mobile network is formed which is advantageous to the gas extraction. The construction method of high quality gas channel was determinedby rationally planning working face length,mining times,mining height,and coal pillar size to form a stress environment required by the formation of high quality gas channel. Also,the drilling horizon,direction,space,setting time and other gas drainage borehole layout were determined accordingly,which was able to achieve a high efficiency,stability,long-lasting,and high quality gas channel and greatly improve the extraction efficiency.