Small-scale experimental and theoretical analysis on maximum temperature beneath ceiling in tunnel fire with vertical shafts

By replacing jet fans with vertical shafts to facilitate ventilations, the installation and operating costs of a tunnel reduced drastically. However, compared to jet fans in tunnel ventilation which have been systematically studied, the ventilation efficiency of vertical shafts is much more complicated to be analyzed and theoretically proved as it is affected not only by the quantity of shafts, but also by the arrangements and the dimension of them. In order to provide theoretical support, small-scale experiments and theoretical analysis are carried out in this paper to predict the maximum temperature beneath ceiling when there is a fire in tunnel with vertical shafts. Firstly, a theoretical prediction model is deduced to calculate them under different shaft geometry and arrangements. Secondly, the calculation results of the proposed model are compared with experimental data. The comparisons show that the proposed theoretical model can be used to predict the maximum smoke temperature beneath ceiling.