Saving lives in a road tunnel using transformable elements restricting the propagation of fire products

Abstract

The paper considers various scenarios of fire development in road tunnels. The dynamics of combustion products propagation is studied by taking into account the fire strength, tunnel geometry and layout, and aerodynamics of the ventilation flow. The impact of strong fires on the sustainability and proper operation of ventilation systems is demonstrated, and different types of numerical models are considered with the FDS software environment. Theoretical and numerical experiments have demonstrated that strong fires in tunnels can induce dynamic pressures greater than the static pressures of the tunnel fans. The latter can change the direction of movement of ventilation flows in the tunnels with an inclination of 3% or more when the seat of fire is at a hypsometrical height lower than the air supply portal, thus drastically impairing the self-evacuation capability of people in the disaster zone. It was demonstrated that one of the most reliable ways to save lives in case of fire is to limit the spread of flue gases to prolong the time for evacuation. The paper proposes a transformable flexible system to save lives, which artificially increases the aerodynamic resistance of tunnels to prevent the propagation of harmful combustion products on the people’s evacuation route. By considering the fire development scenarios in horizontal and inclined tunnels, the dynamics of the spread of the fire damaging factors when ventilation system is no longer operable and the only solution is the use of the flexible system is examined. The results of modeling evidence that by closing 50% of the tunnel cross-section with a flexible system it is possible to obtain important positive results in reducing the spread of combustion products and saving lives. The use of the proposed system reduces the intensity of the spread of fire hazards and will definitely help the people in the disaster zone. The analysis carried out clearly shows its necessity and that the comprehensive study of fires and generalization of study results will be useful in adequate planning and implementing future measures to prevent and reduce their harmful effects. Following the above-mentioned, a detailed description, analysis and development of a clear algorithm of action of fire cases, and communicating the results to rescuers, tunnel service personnel and the general public are needed.