Research on ceiling gas temperature rise and floor heat flux driven by strong fire plume in a sealing tunnel

Sealing is one of the important means to extinguish fire in tunnel. It is necessary to investigate the strong fire plume in tunnel under sealed conditions. In this paper, the fire experiments were carried out in a 1:10 tunnel platform, and the influence of different sealing forms, heat release rates of fire source and heights of fire source on the ceiling gas temperature rise and floor heat flux driven by strong fire plume were analyzed. As expected the tests show that the ceiling gas temperature rise under sealing effect will be lower than that without sealing. The larger the total sealing ratio, the greater the temperature rise and floor heat flux. When the total sealing ratio is the same, the higher the proportion of the upper part sealing structure, the larger the ceiling gas temperature rise and the floor heat flux, meanwhile, these two parameters are also positively correlated with the height of fire source. In the region close to the fire source, the longitudinal temperature rise along the ceiling attenuates rapidly, but the decays trend becomes slower as the distance away from the fire source increases. In this paper, the sealing opening coefficient is introduced, and the prediction models of the longitudinal temperature rise decay along the tunnel ceiling and the floor heat flux under sealing effect are proposed respectively.