基于卸压开采的下向穿层钻孔抽采瓦斯技术

Technique of gas drainage with pressure relief by downward crossing boreholes

为了实现下伏被保护层的卸压瓦斯抽采最大化，本文提出了保护层开采采用“Y”型通风沿空留巷技术，同时配合下向穿层钻孔的立体式抽采瓦斯技术，优化确定了下向钻孔的技术参数、施工时间、粉尘防治等工艺难题。工程实践表明，下向穿层钻孔单孔抽采瓦斯纯量可达0．2m^3/min，最大约0．45m^3/min，浓度高达60～90％，高效稳定时间约20～30d，可实现卸压瓦斯的抽采最大化。

To maximize the amount of gas extraction with pressure relief from the underlying protected seam, the technology of downward crossing boreholes with gob-side entry retaining and Y-type ventilation method during protective seam mining was proposed in this paper. Technical parameter de termination of downward drilling holes was optimized and the problems about drilling time and dust control were solved. The experimental results indicate that the average gas drainage volume by single borehole was O. 2m^3/min and the maximum value was about 0. 45m^3/min. The gas concentration re mained at 60-0%. Moreover, the effective period can maintain 20-30 days. In conclusion, the technique of downward crossing boreholes can maximize gas drainage with pressure relief.