水工隧洞过煤层超高压水力切割瓦斯增透技术研究

Research on ultra-high pressure hydraulic cutting technology to improve gas breathability during hydraulic tunnel passing through coal seam

针对水利设施、高速公路、高速铁路过煤层的隧道开挖工程,低透气性煤层所带来的不仅仅是抽采效率低、钻孔施工量大等问题,更严重制约了工程实施进度。以贵州省夹岩水利枢纽工程水打桥隧洞为研究对象,针对水工隧洞过煤层抽采周期长、瓦斯抽采浓度低、衰减快、瓦斯抽采困难等问题,提出了超高压水力切割煤层瓦斯增透技术。研究了超高压水力切割煤层的破岩机理,开发了超高压煤层水力切割设备,分析了水力压力与切割的半径、瓦斯抽采量、瓦斯自排量及残存瓦斯含量的关系。实践表明:实施超高压水力切割瓦斯增透后,该区域内的瓦斯透气性系数提高了17.82倍,平均瓦斯抽采浓度和纯量分别提高了3.50倍和4.70倍,超高压水力切割瓦斯增透效果显著。相关经验可供类似工程借鉴。

Tunnel excavation of water conservancy facilities,expressway,high-speed railway and other projects sometimes passes through the coal seam.The low permeability coal seam not only brings problems such as low extraction efficiency and large drilling construction volume,but also seriously restricts the engineering progress.Taking the Shuidaqiao Tunnel in the Jiayan Hydropower Project of Guizhou Province as anexample,in view of the problems existing in the process of hydraulic tunnel passing through coal seam,such as long extraction period,low gas extraction concentration,fast attenuation and difficult gas extraction,the ultra-high pressure hydraulic cutting technology to improve the gas breathability was proposed.In this paper,the rock breaking mechanism of the ultra-high pressure hydraulic cutting coal seam was introduced,as well as the super-high pressure hydraulic cutting equipment.The relationship between hydraulic pressure and cutting radius,gas extraction volume,gas self-displacement and residual gas content were also analyzed.The practices showed that after implementing the ultra-high pressure hydraulic cutting technology,the gas permeability coefficient in the area increased by 17.82 times,and the average gas extraction concentration and pure volume increased by 3.5 and 4.7 times,respectively.