Study on smoke transport characteristics in super large space of covered ground interchange

Based on the fire numerical simulation, the movement characteristics of fire smoke in the super large space above the ground interchange is studied. In view of the characteristics of the overpass tunnel with large span, large space, many diversion and confluence nodes, the smoke layer morphological characteristics and smoke temperature distribution of different longitudinal air velocity under the longitudinal smoke exhaust mode are studied, and the critical air velocity of smoke flow, smoke diffusion characteristics and smoke control technology in the overpass tunnel are analyzed. The results show that after the partition between the lanes in the same direction is removed, due to the expansion of the section, the wind velocity in the original branch ramp can not effectively suppress the smoke countercurrent, and the critical smoke exhaust air velocity will increase; After canceling the same direction partition between ramps, under all calculation conditions, except for the fire source area, the other indicators 1.8 m above the ground meet the needs of personnel evacuation and escape, and the longitudinal smoke exhaust air velocity that controls the smoke not to produce countercurrent is 3.0 m/s.