A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Effects of ventilation on evacuation in tunnel fires
Norwegian road traffic, including transport of goods, is growing and so has the need and ability to build long and deep tunnels. A tunnel fire has a catastrophic potential, so technical measures including ventilation systems are used as replacement for emergency exits or additional tunnel tubes which are very expensive. Originally, tunnel ventilation systems were implemented to handle waste gases and dust from the tunnel, but later this has become one of the most important mitigating measures during fire. The most commonly used ventilation system in Norway are longitudinal ventilation driven by jet fans in the ceiling and using tunnel portals as supply and exhaust. The reason for this is mainly the cost and the fact that transverse systems with vertical shafts are unwanted in densely populated areas, unpractical for tunnels deep into rock and not feasible for sub-sea tunnels. The transverse systems with ducts increase the required tunnel cross-section and become overly expensive. Longitudinal ventilation systems that achieve critical velocity are able to create a smoke-free environment upstream the fire, but often evacuees get trapped at the downstream side of the fire. The issue of downstream evacuation has raised discussions in the tunnel fire safety community and the industry regarding ventilation strategies. This has led to the use of several ventilation strategies, ranging from the ventilation system not starting at all before evacuation is completed to systems running at full power from start. The arguments for not starting the ventilation system is that this can diminish smoke stratification whilst on the other side, arguments are based on the dilution of smoke to an extent that visibility and toxicity does not severely affect the evacuation. This thesis investigate the effects of various ventilation velocities on downstream evacuation conditions using fire- and egress simulation models FDS and STEPS. Fire input data of the simulations are based on full scale tunnel fire test data, including the effect of ...
Effects of ventilation on evacuation in tunnel fires
Norwegian road traffic, including transport of goods, is growing and so has the need and ability to build long and deep tunnels. A tunnel fire has a catastrophic potential, so technical measures including ventilation systems are used as replacement for emergency exits or additional tunnel tubes which are very expensive. Originally, tunnel ventilation systems were implemented to handle waste gases and dust from the tunnel, but later this has become one of the most important mitigating measures during fire. The most commonly used ventilation system in Norway are longitudinal ventilation driven by jet fans in the ceiling and using tunnel portals as supply and exhaust. The reason for this is mainly the cost and the fact that transverse systems with vertical shafts are unwanted in densely populated areas, unpractical for tunnels deep into rock and not feasible for sub-sea tunnels. The transverse systems with ducts increase the required tunnel cross-section and become overly expensive. Longitudinal ventilation systems that achieve critical velocity are able to create a smoke-free environment upstream the fire, but often evacuees get trapped at the downstream side of the fire. The issue of downstream evacuation has raised discussions in the tunnel fire safety community and the industry regarding ventilation strategies. This has led to the use of several ventilation strategies, ranging from the ventilation system not starting at all before evacuation is completed to systems running at full power from start. The arguments for not starting the ventilation system is that this can diminish smoke stratification whilst on the other side, arguments are based on the dilution of smoke to an extent that visibility and toxicity does not severely affect the evacuation. This thesis investigate the effects of various ventilation velocities on downstream evacuation conditions using fire- and egress simulation models FDS and STEPS. Fire input data of the simulations are based on full scale tunnel fire test data, including the effect of ...
Effects of ventilation on evacuation in tunnel fires
Møller, Johan Kristian (author)
2018-01-01
Theses
Electronic Resource
English
DDC:
624
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