Experimental Analysis on the Critical smoke exhaust rate for Large Vent in Tunnel concerning for Plug-holing Phenomenon

Abstract For different combinations of fire heat release rate and longitudinal velocity, a series of experimental tests concerning for plug-holing phenomenon have been carried out on a 1/20 reduced scale model tunnel. Firstly the smoke temperature distribution beneath the tunnel ceiling was given out. And based on the temperature profiles of pile A, B and C, the air-smoke interfaces for three locations were accordingly labeled and flow patterns below the vent were given out. Secondly with the augment of the smoke exhaust rate, the smoke layer decreased. For the case (Q=4.68MW, v=0.33m/s), the stability of upper smoke layer had been broken, when the smoke flow rate increased to 58m 3 /s corresponding to plug-holing phenomenon. Lastly for different combinations of fire heat release rate and longitudinal velocity, the critical smoke exhaust rate can be obtained. And a simple dimensionless correlation, suitable for practical application, was given out.