Full-scale fire tests in the underwater tunnel section model with sidewall smoke extraction

The Hong Kong-Zhuhai-Macau Bridge (HZMB) is a 55-km bridge-tunnel system, including a 6.7-km undersea tunnel that adopts the sidewall smoke extraction system. To evaluate the potential tunnel fire hazards, a 1:1 full-scale HZMB tunnel section model (16 m x 7.2 m x 150 m) was constructed, and eight full-scale tunnel fire tests were conducted with the sidewall smoke extraction. The temperature distribution and smoke movement under different vent arrangements and fire sizes (1.2-6.6 MW) were quantified. Results indicated that the fire HRR was mainly affected by the size of the liquid-fuel pool but insensitive to the arrangement of ventilation. The correlation between HRR and diesel pool-fire area can be fitted by a linear function of HRR = 1.24A(F)-0.87 MW. The sidewall smoke extraction generated a tilted fire plume and non-uniform temperature distribution at the transverse direction, whereas the temperature decay still followed the exponential decay for the far fire field region. The decay factor increases with the increase of the HRR and increases when distributing the ventilation capability into two vent groups. A relatively slow smoke motion (0.8-1.2 m/s) and good smoke stratification were demonstrated in the tests, indicating a robust condition for safe evacuation. This research deepens the understanding of fire and smoke characteristics in tunnels with the sidewall extraction and highlights the importance of full-scale test data in the development of the smart tunnel-fire protection system.

Automated summary

Through full-scale tests on the tunnel section model of the Hong Kong-Zhuhai-Macau Bridge, the impact of the sidewall smoke extraction system on tunnel fires was evaluated. The results showed that the fire heat release rate was primarily affected by the size of the liquid-fuel pool and insensitive to ventilation arrangements. The tests demonstrated slow smoke motion, good smoke stratification, and provided a stable condition for safe evacuation. This research deepens the understanding of fire and smoke characteristics with sidewall extraction and emphasizes the importance of full-scale test data for the development of smart tunnel-fire protection systems.