The influence of diffuse terminal parameters on its local oxygen enrichment performance in high-altitude railway tunnels

Oxygen enrichment is essential for worker safety for high-altitude tunnel construction. To improve the design of oxygen-enrichment system, this study conducted a validated simulation to investigate the effect of diffuse terminal parameters on oxygen concentration at the tunnelling face. Relationships amongst terminal parameters, ventilation duct height and oxygen concentration were analysed. Results show that with variations in the terminal parameters, the fraction of the breathing zone meeting the oxygen-enrich criteria fluctuated between 11.76% and 76.47%. Analysis of variance was taken to quantify the relative influence of each terminal parameter on oxygen concentration. A correlation was proposed to predict local oxygen concentration within the workers’ breathing zone in the high-altitude tunnel. The findings can provide guidance for improving practical oxygen-enrichment system design during high-altitude tunnel construction.