Spread and burning characteristics of continuous spill fires in a tunnel

Abstract

Changing burning area of spill fire may cause chain effects and expand consequences in tunnels, which poses a greater challenge to personnel escape and rescue. Research on tunnel spill fire is needed to reveal its behavior and internal mechanisms. This paper carried out a series of continuous spill fires on fireproof glass both in tunnel environment (TE) and open environment (OE). The spread, burning, and heat transfer characteristics were compared between these two environments. The results showed that spread areas of TE spill fires in quasi-steady stage were smaller than those of OE. The burning rate enhancement coefficients ranged from 0.92 to 1.76 from small spill fires and larger ones in tunnel. With respect to penetrating heat radiation and heat conduction loss, TE spill fires were slightly larger than OE spill fires. And it was proved that the heat feedback is the main cause for the burning rate enhancement in tunnel. Then a semi-empirical model was proposed by coupling the spread, burning and heat transfer process. The model was proved to be quite accurate by validating with experimental data.