中文摘要：

松软煤层钻孔在钻进及抽采瓦斯过程中，容易发生钻孔形变、缩径、坍塌甚至堵孔等工程问题，造成瓦斯钻孔成孔率低、密封性差、服务时间短及瓦斯抽采阻力大等抽采问题。针对上述技术难题，基于松软煤层的构造演化过程，分析了自重应力、构造应力、采动应力及瓦斯应力等因素对松软煤层瓦斯钻孔稳定性的影响，得出了松软煤层钻孔的多应力耦合作用失稳机制。同时，针对松软煤层瓦斯钻孔失稳规律，提出以护孔为基础，自适应动态密封为关键的“护–封”一体化松软煤层瓦斯钻孔密封技术。工程试验结果表明，该技术可使单孔瓦斯抽采体积分数增加至90%以上，单孔瓦斯体积分数提高2~3 倍，且抽采浓度稳定。

英文摘要：

The engineering problems such as borehole shrinkage, deformation, wall collapse and plugging holes areprone to result in drainage problems such as low hole-making rate, poor sealing, short service time and big resistanceof drainage during drilling and gas extraction. Aiming at the above-mentioned problems, based on the tectonicevolution of soft coal seams, the paper analyzed the effects of gravity stress, tectonic stress, mining-inducedstress and gas stress on the stability of gas drainage boreholes in soft coal seam, the paper obtained the instabilitymechanism of borehole under the coupling effect of multiple stress. And according to the instability law of gasdrainage borehole in soft coal seam, it proposed the the integrated protection and sealing technology of gas drainageborehole in soft coal seam, that is to take protecting hole as the basis and self-adaptive dynamic sealing ascritical. Engineering tests show that the sealing system made the gas extraction concentration increase to above90% in single hole and the gas concentration of the single hole increase by 2 ~ 3 times, the extraction concentrationwas stable.