为解决小倾角高压瓦突煤层底部瓦斯抽排困难，改善瓦斯抽排效果，依托贵州正安至习水高速公路桃子垭隧道，对穿越小倾角高压瓦突煤层段瓦斯抽排进行研究。基于隧道开挖过程中开挖断面与煤层空间位置关系的变化特点，提出分步、分区的煤层瓦斯抽排方案； 并利用热传导理论与瓦斯流动理论的相似性，采用热力学有限差分计算软件模拟分析隧道小倾角煤层的瓦斯防突抽排过程和实施效果。研究表明： 1）分步、分区的煤层瓦斯抽排方案可避免底部煤层超长抽排钻孔打设，较整体一次性抽排方案，钻孔长度减少31%，且施工更便捷、消突更可靠； 2）煤层断面抽排钻孔均匀布设时，中间钻孔抽排区域提早达到消突目标，而边缘区域滞后，采用边缘密、中间疏的抽排钻孔布设方式更合理； 3）对比沿煤层倾向打设的抽排钻孔和以斜交打设穿透煤层面的抽排钻孔模拟效果，前者抽排效率较后者提高约1/3，且瓦斯压力消散更均匀； 4）瓦斯抽排工期可根据抽排模拟计算进行预估，其值大致介于抽排区域平均瓦斯压力和最大瓦斯压力降至瓦斯突出临界压力的时长之间。

The extraction of gas at the bottom of coal seams with low-angle high-pressure gas outbursts is difficult, which reduces the extraction efficiency. To address this issue, a case study is conducted on the Taoziya tunnel on the Zheng′an-Xishui expressway in Guizhou, China. Based on the variation in the spatial position relationship between the excavation section and coal seam during tunnel excavation, a step-by-step and zoned coal seam gas extraction plan is proposed. The similarity between heat conduction theory and gas flow theory is leveraged by the thermodynamic finite difference calculation software to simulate and analyze gas outburst prevention and extraction as well as the effect of constructing a tunnel in the small-angle coal seam. Results are as follows: (1) The step-by-step and zoned coal seam gas extraction scheme prevents the drilling of super-long discharge boreholes in the bottom coal seam, thereby reducing the total drilling length by 31% compared to the overall one-time extraction scheme; it is also proving more efficient and reliable. (2) Gas extraction simulation results show that when the extraction boreholes are evenly distributed on the coal seam section, the middle drilling and extraction areas reach the gas outburst elimination target earlier and the edge area lags behind. Therefore, adopting a dense edge and sparse middle extraction and extraction borehole layout method is reasonable. (3) A comparison of simulation results of drainage boreholes drilled along the coal seam dip and those drilled obliquely through the coal seam shows that the former improves drainage efficiency by ~1/3, with more uniform gas pressure dissipation. (4) The gas extraction period can be estimated via simulation based on the extraction plan, which is roughly between the time when the average gas pressure in the extraction area reduces to the critical pressure of the outburst and the time when the maximum gas pressure decreases to the critical pressure of the outburst.