Optimization for diffusion-type oxygen supply nearby working face of railway tunnel in plateau

During the construction of railway tunnels in plateau environment regions, ensuring adequate oxygen supply is crucial for both worker health and safety, and tunnelling progress. Existing diffusion-type oxygen supply enrichments for plateau regions lack quantitative conclusions and have not been implemented systematically in actual engineering. To refine the design parameters of the required method, this study utilized computational fluid dynamics (CFD) to examine the optimal design parameters for oxygen supply equipment in a typical engineering project. The optimal scheme consisted of three rows of oxygen diffusion apparatuses with 0.07 m inlet diameter, 0.4 m lateral spacing and 60° tilt that maintain a constant oxygen supply rate. This configuration maximized oxygen concentration enrichment in workers’ breathing zones, with oxygen partial pressure in most target zones remaining below 3000 m altitude, except for the ventilation side where it was 3360 m. This study elucidated the effects of various design parameters on oxygen distribution and proposed the optimal combination for a typical tunnel engineering project. The findings provide a guidance for implementing diffusion-type oxygen enrichment in high-altitude tunnel construction, aiding both worker safety and project efficiency.