高原瓦斯隧道“风帘+巷道式”通风方案应用研究

Investigation of the“wind curtain+tunnel-type”ventilation system in high-altitude gas tunnels

合理的通风方案设计是保证高原瓦斯隧道安全施工的基础。针对高原瓦斯隧道通风难度大、施工危险性高等难题,基于“风帘+巷道式”通风方案,采用通风网络设计计算、Fluent数值模拟计算与工程现场应用的方法,探究“风帘+巷道式”通风方案在高原瓦斯隧道中的应用效果。结果表明:“风帘+巷道式”通风方案不但能满足大风量通风需求,而且风帘的设计可有效解决瓦斯回流问题,保证运输安全;基于Fluent数值模拟计算,揭示了瓦斯气体具有贴壁扩散的规律,瓦斯先聚集于隧道顶部后贴壁扩散到隧道内,且回风侧的瓦斯体积分数高于风管侧,在距掌子面20 m外,所有指标均满足安全施工规范要求,各断面瓦斯平均体积分数低于0.5%,通风效果显著。研究可为类似的高原瓦斯隧道通风方案实施提供参考。

To tackle the ventilation challenges in high-altitude gas tunnels—characterized by low air pressure,low air density,reduced oxygen levels,significant temperature variations,and difficulties in controlling gas diffusion—this paper proposes a“wind curtain+tunnel-type”ventilation scheme.These factors contribute to increased ventilation difficulties and heightened construction risks.First,the“wind curtain+tunnel-type”ventilation network is designed,and its effectiveness in meeting ventilation requirements is assessed based on the principles of wind pressure balance and air volume balance.Next,gas migration patterns during ventilation are analyzed using Fluent numerical simulations to evaluate the feasibility of the proposed scheme.Building on this analysis,the practical effectiveness of the“wind curtain+tunnel-type”ventilation system is validated through its implementation in a real high-altitude gas tunnel project.The research results indicate that the“wind curtain+tunnel-type”ventilation scheme not only satisfies the requirements for high air volume ventilation but also effectively mitigates gas recirculation through the wind curtain design,thereby enhancing transportation safety.During the ventilation process,airflow speeds at the corners of the duct are significantly higher than in other areas.Utilizing high-strength ventilation ducts can effectively withstand the impact and damage caused by this increased wind flow.Based on Fluent numerical simulations and field applications,it was observed that within 30 meters of the working surface,gas flows along the tunnel crown towards the sidewall,where there are no ventilation ducts,subsequently dispersing across the working surface.As the distance from the working surface increases,the gas concentration in the cross-sections gradually diminishes.Beyond 20 meters from the working surface,the average gas concentration in all cross-sections falls below 0.5%.This indicates that there is no gas accumulation within the tunnel,and all indicators comply with safety construction standards,highlighting the significant effectiveness of the ventilation system.