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| Research on calculation model of critical smoke control velocity for evacuation passages in shield tunnels |
| Luo Chiheng1, Guo Yuanjun2, Jia Yao2, Jiang Xuepeng2
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| (1.China Railway Siyuan Survey And Design Group Co., Ltd., Wuhan 430063,Hubei,China; 2.School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430081,Hubei,China） |
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Abstract To determine the critical smoke control velocity for safety evacuation passageways located beneath the carriageway of shield tunnels, a theoretical model based on the Froude number was developed and validated via FDS numerical simulations and reduced-scale experiments. An implicit governing equation for the critical smoke control velocity was theoretically derived by considering the effects of longitudinal tunnel velocity, fire heat release rate, and tunnel height. The results showed that the critical smoke control velocity decreased linearly with increasing longitudinal tunnel velocity, increased linearly with increasing fire heat release rate, and decreased exponentially with increasing tunnel height. Meanwhile, a critical Froude number of 12 was identified as the threshold for preventing smoke ingress into the safety evacuation passageway. The proposed theoretical model was further validated in a 1:10 reduced-scale experiment, and the maximum absolute deviation between the calculated and measured velocities did not exceed 0.05 m/s, demonstrating the satisfactory predictive accuracy of the model. The results can provide a theoretical basis for the design of pressurized ventilation systems and the determination of critical smoke control velocities in safety evacuation passageways of shield tunnels.
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Received: 21 April 2026
Published: 14 September 2026
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