页岩地层瓦斯钻孔抽排参数研究——以白云山隧道为例

Research on Gas Drilling and Drainage Parameters in Shale Formation—A Case Study of Baiyun Mountain Tunnel

摘要: 页岩地层隧道施工中，掌子面前方岩体瓦斯压力过高是诱发岩体与瓦斯突出的主要因素。本文以白云山隧道为实际工程，基于流固耦合理论，建立数值模型，系统研究了抽排钻孔直径、抽排时间、抽排负压及钻孔间距对瓦斯抽排效果的影响规律。研究结果表明：当钻孔直径在0.100~0.125 m时有效抽排半径增量最大；抽排时间与有效抽排半径符合幂函数方程，抽排时间2 d时有效半径增量达到最大；抽排负压在一定范围内对有效抽排半径影响微弱；钻孔间距控制在1.5 m时，两孔抽排叠加效应明显，残余瓦斯压力位于0.74 MPa以下。揭示了瓦斯抽排参数与抽排效果的定量关系，确定了白云山隧道的最优钻孔参数，为类似的页岩地层隧道瓦斯防治提供理论依据与技术参考。

Abstract: In the construction of tunnels through shale formations, excessive gas pressure in the rock mass ahead of the working face is the primary factor inducing rock and gas outbursts. Taking the Baiyun Mountain Tunnel as a practical case, this study establishes a numerical model based on fluid-solid coupling theory to systematically investigate the influence of borehole diameter, extraction time, extraction negative pressure, and borehole spacing on gas extraction efficiency. The findings reveal: when the borehole diameter ranges between 0.100~0.125 m, the effective extraction radius increment reaches its maximum; the extraction time and effective extraction radius conform to a power function equation, with the effective radius increment peaking at 2 days of extraction; within a certain range, extraction negative pressure has minimal impact on the effective extraction radius; when borehole spacing is controlled at 1.5 m, the superposition effect of dual borehole extraction is pronounced, keeping residual gas pressure below 0.74 MPa. This study quantifies the relationship between gas extraction parameters and efficiency, determines the optimal borehole parameters for the Baiyun Mountain Tunnel, and provides theoretical foundations and technical references for gas prevention in similar shale formation tunnels.