Numerical simulation and experimental study on oxygenation of tunnel face in plateau tunnel construction

In order to investigate the effect of different oxygenation schemes on oxygen enrichment under different working conditions during the construction of the tunnel face of a large section tunnel on a plateau highway and to solve the quantitative problem of the oxygen enrichment model, a full-size numerical model of the tunnel face and a 1:30 experimental model were established for a plateau highway tunnel. These were used for numerical simulation and experimental research. The results indicate that the oxygen enriched area is piled up in the shape of a round bench when a construction bench is present, whereas in the absence of a construction bench, the oxygen enriched area assumes the shape of a slanting droplet. Furthermore, the oxygen enriched programs with oxygen delivery distances of 9 m, 8 m, and 7 m are unable to deliver the oxygen to the tunnel face. In the absence of a construction bench, the oxygenation effect is enhanced when the distance between the oxygen outlet and the tunnel face is 0.5 m. The oxygen released from different locations in multiple ports is distributed along the tunnel’s oxygen distribution range, which extends from three ports to two ports to one port. The number of oxygen ports affects the initial velocity of oxygen, which is susceptible to wind flow field influence. It is challenging to direct the flow of oxygen along the oxygen ports. The oxygen enriched volume of the different oxygen enriched programs in the tunnel under different working conditions can be quantified according to the multivariate linear regression oxygen enriched model, which can serve as a reference for optimizing oxygen enriched programs.