Experimental study on the smoke plug-holing phenomenon and criteria in a tunnel under the lateral smoke extraction

作者：Zhu, Yuantao; Tang, Fei^*; Huang, Yajun

来源：TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY, 2022, 121: 104330.

DOI：10.1016/j.tust.2021.104330

• Tunnel fire
• Plug-holing
• Smoke temperature
• Lateral smoke extraction
• Froude number

This work focused on the study of smoke plug-holing phenomenon with the effect of lateral smoke extraction system in tunnel fires. The reduced tunnel model was used to conduct experiments with various test conditions, the smoke plug-holing phenomenon at extraction vents with different aspect ratios were analyzed. It was found that, the smoke temperature rise under tunnel ceiling firstly decreased as the increasing the lateral smoke extraction velocities, and then show a trend of increase or remained stable, which can be explained by the plug holing phenomenon occurs as lateral smoke extraction velocity reaches a certain value. As the aspect ratio of the lateral smoke extraction vent increases, the smoke extraction velocity required for the smoke layer occurs plug holing phenomenon also increases correspondingly, and the previous classic empirical description model for the smoke plug-holing criterion is no longer suitable for tunnel fires with lateral smoke extraction. Then, a revised Froude number is proposed to determine smoke plug-holing phenomenon in a tunnel under the effect of lateral smoke extraction, the updated criterion can be used to evaluate smoke plug-holing phenomenon of tunnel fires with lateral smoke extraction system. The critical Froude numbers were approximately between 1.5 and 1.75. Meanwhile, with the aspect ratio of lateral smoke extraction vent increased, the critical Froude number also increased accordingly, the increase in the aspect ratio of lateral smoke extraction vent, the occurrence of smoke plug-holing phenomenon will be further reduced.