Abstract: In order to prevent the fire smoke from spreading to the tunnel entrance, it is poured into the adjacent non?accident tunnel under the action of environmental wind. In this paper, the characteristics of smoke backflow at the entrance of a traffic tunnel with a slow?moving road under different wind speeds are studied by numerical simulation. The results show that the intrusion rate of fire smoke increases with the increase of ambient wind when no smoke control measures are taken in the non?accident holes, and increases with the increase of environmental wind. The smoke?proof wind speed of the driveway to prevent the backflow of smoke increases with the increase of the ambient wind speed and changes linearly. The normal operating wind speed 0.5 m/s of the slow lane can prevent the back flow of smoke into the slow lane. It was found that when the opening rate of the natural smoke exhaust outlet of the closed sound barrier is set to 10%, the natural smoke extraction scheme with continuous opening and vertical wall is the best, and the penetration rate of fire smoke to non?accident holes is the lowest.

Key words: tunnel, slow lane, smoke backflow, cooperative smoke control, sound barrier