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为了系统分析割缝预抽后钻孔周围煤体孔隙结构变化特征,基于孔隙结构测试方法的敏感性和精确性及液氮吸附法和压汞法测定原理,提出将液氮吸附法和压汞法有机结合来表征煤体孔隙结构。结果表明:1二者的有机结合应满足填充临界孔径所需的实验介质体积相等且结合点平滑过渡;2随取样点与割缝孔距离的减小,小孔(10~100nm)所占比例显著降低,大孔(>1 000nm)所占比例逐渐提高,中孔(100~1 000nm)和微孔(<10nm)所占比例变化较小;3割缝预抽后煤体瓦斯放散初速度ΔP受取样点与割缝孔距离的影响。水力割缝与瓦斯抽采协同作用能够弱化煤体对瓦斯的吸附能力并显著提高瓦斯在煤体中的渗流能力。研究结果对于指导高压水射流割缝瓦斯预抽具有重要意义。
In order to systematically analyze the change characteristics of pore structure of coal around the borehole after pre-pumping of kerf, based on the sensitivity and accuracy of pore structure test method and the principle of liquid nitrogen adsorption and mercury intrusion porosimetry, Law organic combination to characterize the pore structure of coal. The results show that: 1 the organic combination of the two should meet the experimental medium required to fill the critical pore volume equal and the smooth transition of the junction; 2 with the sampling point and the slit gap decreases, the proportion of small holes (10 ~ 100nm) (100 ~ 1 000 nm) and micropores (<10 nm) accounted for a small proportion. The average initial velocity of coal gas emission after 3-slot pre-pumping ΔP is affected by the distance between the sampling point and the slotted hole. The synergistic effect of hydraulic kerf and gas drainage can weaken the adsorption capacity of coal to gas and significantly increase the seepage capacity of coal in gas. The research results are of great significance for guiding pre-pumping of high-pressure water jet cutting seam gas.