以工程实验为基础，结合屯兰矿现有瓦斯抽放中封孔工艺，主要针对封孔长度，通过理论分析，确定合理的封孔长度。
Based on engineering experience and combined with presently hole-sealed technology of gas drainage used in Tunlan mine, the reasonable hole-sealed length was determined by theoretical analysis.
针对煤层钻孔抽放瓦斯后煤层孔隙裂隙发育致使瓦斯浓度下降，钻孔有效抽放期缩短的技术难题，首次提出二次封孔方法。
Gas concentrations drop, and the effective gas drainage period of holes is shortened, because pores and cracks in the coal seam become completely developed after gas drainage.
高压水射流径向水平孔钻进技术是水平孔施工技术之一，它是在垂直瓦斯抽放或煤层气勘探钻孔布置机械或水力扩孔装置，对准选定的煤层部位进行扩孔。
As one of radial horizontal drilling techniques, high pressure water jet drilling technology is capable of using mechanical or water jet apparatus to make a cavity at the selected coal seam.
目前在瓦斯抽放中急待解决的问题是软煤层瓦斯抽放的打钻技术，尤其是深孔打钻技术。
At the present, the problem which is urgently to be solved in gas discharge is the drilling technology in soft coal seam gas discharge, especially the drilling technology of the deep hole.
煤层深孔预裂爆破近年来在瓦斯抽放中运用日益增多，但目前对其爆破理论研究较少。
The technique of deep-hole presplitting blasting in coal bed is widely used for gas predrainage recently; but its blasting theory is not clear up to now.
简要论述了深孔爆破提高瓦斯抽放的机理，以煤体中柱状装药爆炸后的裂隙圈半径进行了计算。
The principle of increasing gas emission rate by long hole blasting in the crossing hole is discussed. The radius cracked zone in coal seam caused by long hole blasting is calculated.
简要论述了深孔爆破提高瓦斯抽放的机理，以煤体中柱状装药爆炸后的裂隙圈半径进行了计算。
The principle of increasing gas emission rate by long hole blasting in the crossing hole is discussed. The radius cracked zone in coal seam caused by long hole blasting is calculated.
应用推荐