特长公路隧道压入式和巷道式通风有害气体扩散规律研究OA

To investigate the impact of different construction ventilation schemes on harmful gases diffusion in extra-long highway tunnels,this study is based on the Daliangshan No.1 Extra-Long Highway Tunnel a critical project along the Leshan-Xichang Expressway in Sichuan Province.Based on the species transport model in the computational fluid dynamics(CFD)software Fluent,numerical simulation models are established for forced ventilation in the main tunnel and pilot tunnel,as well as for coordinated gallery ventilation.The models reveal the spatiotemporal distribution patterns and dispersion mechanisms of harmful gases under both ventilation modes,and examine the spatiotemporal effects of transitioning between construction ventilation schemes on gas diffusion.The results indicate that during tunnel construction ventilation,jet zones,recirculation zones,and vortex zones are present in the fluid domains of both the main tunnel and pilot tunnel,with jet zones exhibiting lower gas concentrations,recirculation zones maintaining relatively uniform gas distributions,and vortex zones demonstrating gradient variations in gas concentration.Gas accumulation is observed at the arch foot of the tunnel face and in the area beneath ventilation ducts near the tunnel floor.During forced ventilation,both the spatial extent of the high-concentration gas zone ahead of the pilot tunnel face and the gas concentration levels at its floor level exceed those observed in the main tunnel.In contrast,gallery ventilation significantly reduces the extent of high-concentration gas zones ahead of the faces in both the main and pilot tunnels,while simultaneously enhancing construction ventilation efficiency and reducing energy consumption.