Abstract
Tunnel fires are one of the most dangerous catastrophic events that endanger human life. They cause damage to infrastructure because of the limited space in the tunnel, lack of escape facilities, and difficulty that intervention forces have in reaching the fire position, especially in highly crowded areas, such as Makkah in the Hajj season. Unfortunately, performing experimental tests on tunnel fire safety is particularly challenging because of the prohibitive cost, limited possibilities, and losses that these tests can cause. Therefore, large-scale modeling, using fire dynamic simulation, is one of the best techniques used to limit these costs and losses. In the present work, a fire scenario in the Makkah’s King Abdulaziz Road tunnel was analyzed using the Fire Dynamics Simulator (FDS). The effects of the heat released per unit area, soot yield, and CO yield on the gas temperature, radiation, concentrations of the oxygen and combustion products CO and CO2, and air velocity were examined. The results showed that the radiation increased with the heat released per unit area and the soot yield affected all parameters, except the oxygen concentration and air velocity. The CO yield significantly affects CO concentration, and its influence on the other studied parameters is negligible. Moreover, based on the validation part, the results proved that FDS have limitations in tunnel fires, which impact the smoke layer calculation at the upstream zone of the fire. Therefore, the users or researchers should carefully be concerned about these weaknesses when using FDS to simulate tunnel fires. Further comprehensive research is crucial, as tunnel fires have severe impacts on various aspects of people’s lives.
Highlights
The flame is spread very quickly, so that the source of fire changed from one point to another
The gas temperature, gas concentrations, radiation fluxes and air velocity were simulated at the different locations
While a grid sensitivity analyses (30 cm, 48 cm, and 60 cm) were evaluated, the results proved that Fire Dynamics Simulator (FDS) have limitations in tunnel fires, which impact the smoke layer calculation at the upstream zone of the fire
Summary
The flame is spread very quickly, so that the source of fire changed from one point to another. The spread of flame in a solid surface, such as walls or combustible materials, is considered a significant issue that increases the propagation of fire and raises the heat. The wall lining could burn and spread the fire very quickly, so that the fire source will transfer to one or more sources [1,2,3,4,5]. Most fire deaths do not occur because of burns, but because of smoke inhalation. When a fire reaches the growth stage, the smoke loaded with toxic gases spreads in the space completely and rapidly, which prevents people from accessing emergency exits
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