针对煤矿井下瓦斯抽采钻孔施工中，瓦斯超限、煤与瓦斯突出事故易发的难题，分析了传统简易孔口装置与常开式自动孔口防喷系统存在的问题，提出采用常闭式防喷系统及方法。常闭式防喷系统可与钻机本体集成，满足各种异形巷道孔口密封、排渣及抽气使用需求；同时控制系统可与钻机电液控系统联动，实现孔口防喷系统泄压自动关闭，防止孔内瓦斯泄露。该防喷系统与传统及现有孔口防喷系统相比系统简洁明了，与钻机适配性更强，钻孔防喷治理效果显著提升，工人劳动强度明显降低，可为煤矿井下瓦斯抽采钻孔施工的安全性提供有力保障。

In view of the problems of gas overrun and coal and gas outburst accidents in the construction of underground gas extraction boreholes in coal mines, the problems existing in the traditional simple orifice device and the normally open automatic orifice prevention system were analyzed, and the normally closed blowout prevention system and method were proposed, which could be integrated with the drilling rig body to meet the needs of various special-shaped roadway orifice sealing, slag discharge and gas extraction. At the same time, the control system can be linked with the hydraulic control system of the drilling machine to realize the automatic closing of the pressure relief of the blowout prevention system at the orifice to prevent the leakage of gas in the hole. Compared with the traditional and existing orifice blowout prevention systems, the blowout prevention system is simple and clear, has stronger adaptability to the drilling rig, significantly improves the effect of drilling blowout prevention and treatment, and significantly reduces the labor intensity of workers, which can provide a favorable guarantee for the safety and efficiency of underground gas extraction drilling construction.