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A study on the fire characteristics according to the installation type of large smoke exhaust port in a small cross sectional tunnel fire

소단면 대심도 터널 화재시 대배기구의 설치형태에 따른 화재특성 연구

  • Received : 2018.12.10
  • Accepted : 2019.01.03
  • Published : 2019.01.31

Abstract

Recently, due to the efforts to mitigate traffic congestion and expansion of space efficiency, the construction of underground roads has been increased in big-scale cities. Since tunnels in the city have a higher chance for a fire leading to a great tragedy during a severe traffic jam than mountain tunnels, it is highly likely that it will be constructed as a tunnel, having a small cross section, for small vehicles. However, if they are constructed as such small-vehicle tunnels, it would be possible to reduce the design fire intensity while the concentration of harmful gases would increase due to a reduction in the small cross sectional area, led by a decrease in the tunnel height. In this study, behaviors of fire smoke by the installation interval and format of large-scale exhaust-gas ports were examined and compared in the analysis of temperatures and CO concentrations of a tunnel and its results were as the following. Although there were no significant differences in the smoke spreading distance between installation intervals, but in this study, 100 m was found to be the most effective installation interval. The smoke exhaustion performance was found to be excellent in the order of $4m{\times}3m$, $6m{\times}2m$, and $3m{\times}2m$ (2 lane) of the smoke spreading distance. Although there was no significant difference in the smoke spreading distance between formats of large-scale exhaust-gas ports, it was found that the smoke spreading distance was larger than other cases when it was $3m{\times}2m$ in the fire growing process. The analysis of smoke spreading distances by the aspect ratio showed that a smoke spreading distance was shorted when its the smoke spreading distance was found to be shorter when its traverse distance was relatively longer than its longitudinal distance.

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Fig. 1. Cross-section

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Fig. 2. Type of smoke exhaust port

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Fig. 3. Simulation domain

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Fig. 4. Fire growth (HRR) curve

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Fig. 5. Diffusion length according to installation distance (upstream)

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Fig. 6. Diffusion length according to installation distance (downstream)

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Fig. 7. Diffusion length according to installation size (upstream)

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Fig. 8. Diffusion length according to installation size (downstream)

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Fig. 9. Diffusion length according to aspect ratio (upstream + downstream)

Table 1. Case of simulation

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Table 2. Boundary conditions & calculation method

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Acknowledgement

Grant : 대심도 복층터널 설계 및 시공 기술개발

Supported by : 국토교통과학기술진흥원

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