顶板水力挠动强制卸压煤层瓦斯抽采工程实践*

对塑性松软煤体进行水力挠动较难取得理想的瓦斯增浓提效效果，为克服该措施的局限性，使松软煤层有效卸压增透，可将挠动对象转移至煤层顶板砂岩。基于对顶板砂岩水力挠动裂隙发育、延展及煤层卸压增透机理分析，在试验矿井的松软煤层及顶板砂岩中分别施工钻孔进行水力挠动试验，同时采用多级指标对措施后的瓦斯抽采效果进行考察。结果表明:水力挠动作用下砂岩体内部形成有利于下部煤层瓦斯流动的裂隙网络，抽采流量、浓度及累计抽采纯量大幅提高；但由于高压水作用下松软煤体内部发生塑性变形、裂隙堵塞、瓦斯流动性弱化，导致抽采流量、浓度及累计抽采纯量不升反降。研究结果可为松软煤层实施水力挠动提供参考，以期实现较理想的瓦斯治理效果。

Engineering practice of hydraulic disturbance to coal seam roof for forced pressure relief and gas drainage

It is difficult to obtain the ideal goal of gas concentration and efficiency improvement by the hydraulic disturbance on plastic soft coal body.In order to overcome the limitation of this measure,for the aim of gas pressure relief and permeability improvement of soft coal seam,the disturbance object could be transferred to the roof sandstone of coal seam.Based on the analysis of the development and extension of hydraulic disturbance fracture of roof sandstone,and the mechanism of pressure relief and permeability improvement of coal seam,the hydraulic disturbance tests were carried out by constructing boreholes in soft coal seam and roof sandstone in the testing mine respectively,at the same time,the multi-level indexes were used to investigate the effect of gas drainage after applying the measures.The results showed that under the effect of hydraulic disturbance,the fracture network formed in the sandstone was beneficial to the gas flow in the lower coal seam,and the gas drainage flow,concentration and cumulative pure flow increased greatly.On the contrary,under the effect of high-pressure water,the plastic deformation occurred in the soft coal body,the fissures were blocked,the gas flow was weakened,and the gas drainage flow,concentration and cumulative pure flow did not rise but fall.The research results provide reference for implementing hydraulic disturbance in the soft coal seam to achieve more ideal gas control effect.