摘要
Abstract
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 trans-portation and diffusion were dissected under different construction phases,as well as the ventilation flow field char-acteristics 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 be-yond 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 concentra-tion in the vortex zone within 30 m of the working face decreased to 0.32％,and the time required for methane con-centration 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.关键词
公路隧道/瓦斯地层/现场监测/Fluent/运移扩散/通风优化Key words
highway tunnels/gas strata/field monitoring/fluent/transport diffusion/ventilation optimization分类
交通工程
