19th WORLD CONFERENCE OF THE ASSOCIATED RESEARCH CENTRES FOR THE URBAN UNDERGROUND SPACE, Belgrade, Serbia, November 4-7, 2025. (Paper No: 4.2.21, pp. 671-678)
АУТОР(И) / AUTHOR(S): Yunxiao Xin, Yaqiong Wang
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DOI: 10.46793/ACUUS2025.4.2.21
САЖЕТАК / ABSTRACT:
Branching tunnels are a crucial component of underground transportation networks, and their structural shape results in a more complex distribution of wind flow fields in the bifurcated section compared to normal tunnels. Especially, the arch tunnels have a sudden change of cross-section at the bifurcation point, which makes it more difficult to control the spread of smoke in the tunnel at the bifurcation. This paper takes the Dapeng Tunnel of the Shenzhen Outer Ring Expressway as the research object, and studies the fire smoke spreading rule for the merging section of the arch bifurcation tunnel through model experiments. The results show that when the fire source is located in the normal section, the critical wind speed is higher than that of a normal tunnel, and smoke backflow is more likely to occur upstream of the fire source. When the fire source is located in the transition section of the tunnel, smoke tends to accumulate in this section during the spread process and form a long backflow upstream of the fire source. When the fire source is located in the transition section, the critical wind speed is essentially the same as that of a normal tunnel, and smoke tends to accumulate and flow back into the non-fire source bifurcation section in the tunnel transition section. In the transition section of the tunnel, smoke tends to fluctuations at the tunnel roof and eddies at the side walls of the transition section. By increasing the wind speed at the entrance of the main tunnel and ramp, it is possible to significantly suppress smoke backflow and reduce temperature, thereby effectively controlling the scale of the tunnel fire.
КЉУЧНЕ РЕЧИ / KEYWORDS:
Bifurcated tunnel, Arched section, Fire ventilation, Smoke spread, Model experiment
ПРОЈЕКАТ / ACKNOWLEDGEMENT:
This study was financially supported by the Fundamental Research Funds for the Central University, CHD (No. 300102214107), Natural Science Basis Research Plan in Shaanxi Province of China (No. 2024JC-YBQN-0320).
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