超大断面隧道三阶梯施工段风流场规律研究

Study on Airflow Field Law of Three-Step Construction Section in Super-Large Cross-Section Tunnel

摘要: 针对超大断面三阶梯工法隧道通风效率低、风流场不均及瓦斯积聚风险问题，本文提出适配性通风优化策略，揭示复杂工况下风流运动规律。以昭通隧道为研究对象，其断面面积达131 m²，结合需风量修正结果与CFD数值模拟，基于RNG k-ε模型构建三维通风模型，分析各阶梯段风速分布、涡流特征，验证风机与风管布局合理性。研究表明，风筒出口风速13.59 m/s时，掌子面附近形成贴壁射流，0~18 m区域涡流显著，三阶梯下部风流扩散能力较弱，易导致瓦斯积聚。通过调整风筒位置、优化射流角度可有效抑制涡流，提升瓦斯稀释效率。该研究明确三阶梯工法下风流场的非均匀分布特性，为超大断面隧道的通风系统优化及安全施工提供理论支撑。

Abstract: To address the issues of low ventilation efficiency, uneven airflow distribution, and gas accumulation risks in super-large cross-section tunnels constructed by the three-step method, this study proposes an adaptive ventilation optimization strategy and reveals the airflow movement laws under complex working conditions. Taking Zhaotong Tunnel as the research object with a cross-sectional area of 131 m², a three-dimensional ventilation model was established based on the RNG k-ε model, integrating corrected air demand results and CFD numerical simulation. The wind speed distribution and vortex characteristics in each step section were analyzed, and the rationality of fan selection and air duct layout was verified. The results indicate that when the air duct outlet wind speed is 13.59 m/s, a wall-attached jet is formed near the working face, with significant vortices in the 0~18 m region. The lower part of the three-step structure exhibits weak airflow diffusion capacity, which is prone to gas accumulation. Adjusting the air duct position and optimizing the jet angle can effectively suppress vortices and improve gas dilution efficiency. This study clarifies the non-uniform distribution characteristics of the airflow field under the three-step construction method, providing theoretical support for the ventilation system optimization and safe construction of super-large cross-section tunnels.