摘要
针对高瓦斯地层公路隧道施工安全和通风优化问题,以寨门口隧道为研究对象,采用现场监测和数值模拟相结合的方式,从瓦斯浓度、瓦斯涌出量参量出发,分析了隧道内瓦斯浓度和涌出量变化规律,进一步剖析了不同工序下瓦斯运移扩散特征和隧道通风流场特征,最终提出了对现有通风系统的优化措施并验证其效果。结果表明:瓦斯浓度均呈现“掌子面>二衬台车>回风流”的趋势,相同区域位置瓦斯平均浓度左洞高于右洞;钻孔爆破和出渣运输2个阶段瓦斯涌出量约占单个施工循环中瓦斯涌出总量的70%;距掌子面30 m以内各断面瓦斯浓度呈现风管处最低、向外扩散升高的趋势,30 m以外均匀分布,其中左拱肩和左拱脚两处瓦斯积聚程度较高;隧道流场分为涡流段、发展段和稳定段3个区段,涡流段的复杂流场特征是瓦斯浓度分布不均、局部瓦斯积聚的主要原因;优化通风措施后,掌子面30 m内涡流段瓦斯平均浓度降至0.32%,瓦斯浓度下降至稳定状态的时间从21 min缩短至13 min。研究成果对同类型高瓦斯公路隧道施工及通风优化具有一定的参考价值。
Addressing safety and ventilation optimization challenges in highway tunnel construction with high-gas strata,the Zhaimenkou Tunnel was taken as a study subject.By a combination of field monitoring and numerical simulation,the variation patterns of methane concentration and outburst volume within the tunnel was analyzed based on methane concentration and outburst volume parameters.Furthermore,the characteristics of methane transportation and diffusion were dissected under different construction phases,as well as the ventilation flow field characteristics of the tunnel.Ultimately,the optimization measures for the existing ventilation system were proposed and the effectiveness was verified.The results indicate that methane concentrations consistently follow the trend of"working face>secondary lining formwork>return airflow."In the same area,the average methane concentrations of the left tunnel were higher than the right tunnel;Methane outburst volumes accounted for approximately 70%of the total methane outburst volume per construction cycle during drilling/blasting and spoil transportation;Within 30m of the working face,the methane concentrations were lowest at the air duct and increased outward.While beyond 30 m,the concentrations distributed uniformly,with higher accumulation at the left arch shoulder and left arch toe;The tunnel flow field was divided into three zones of vortex zone,development zone,and stable zone.The complex flow characteristics in the vortex zone were the primary cause of uneven methane concentration distribution and localized methane accumulation;Following ventilation optimization measures,the average methane concentration in the vortex zone within 30 m of the working face decreased to 0.32%,and the time required for methane concentration to stabilize was reduced from 21 minutes to 13 minutes.These findings provide valuable reference for construction and ventilation optimization in similar high-methane highway tunnels.
作者
刘强
LIU Qiang(China Railway Eighteen Bureau Group Tunnel Engineering Co.,Ltd.,Chongqing 400000,China)
出处
《市政技术》
2025年第12期55-64,共10页
Journal of Municipal Technology
关键词
公路隧道
瓦斯地层
现场监测
FLUENT
运移扩散
通风优化
highway tunnels
gas strata
field monitoring
fluent
transport diffusion
ventilation optimization
