Full-scale Experimental Research on the effect of Smoke Exhaust Strategies on Efficiency of Point Extraction System in an Underwater Tunnel

Fire smoke brings a severe threat to the tunnel users, especially in underwater tunnels, with greater difficulties in smoke control and human evacuation. A series of fire tests were conducted in a full-scale three-lane underwater experiment tunnel. The efficiency of smoke exhaust system was analyzed through comparison the influence of different opening modes of smoke vents. Experimental results show that the fire-induced smoke trends to maintain stable stratification at the top of tunnel. The temperature at the smoke vents in side walls decreases with the reduction of height. The temperature at the smoke vents rises rapidly after ignition, but it will decrease quickly after smoke exhaust fan is started up. Afterwards, the temperature at the smoke vents will rise gradually again with the increase of fire scale. The total volume rate of smoke vents of opening two continuous groups of smoke vents in the downstream is higher than that of opening two spaced groups of smoke vents in the downstream. Besides, both of them are higher than that of only opened one group of smoke vents. The efficiency of smoke exhaust system of the test case opened two continuous downstream groups of smoke vents was much the same as that of the test case opened two spaced downstream groups of smoke vents. And these all were larger than the efficiency of smoke exhaust system of the test case only opened one downstream group of smoke vents.