Abstract:Abstract：Controlling the flue gas occupies a very important position in the tunnel fireproof safety design when the fire happens, and the critical wind velocity which is the minimum airflow speed without reflux can effectively control the flue gas at the source of fire under the direction of the wind in the process of tunnel fire , and it is the key to control the tunnel fire smoke. The CFD numerical simulation software simulated the smoke diffusion of different fire conditions of the road tunnels, and using SAP2000 respectively calculates the internal force size of the reinforced concrete tunnel in different critical wind velocity of different fire source locations when fire happens. After the comparative analysis, it should be appropriate to increase the critical wind velocity, so that it can effectively control the spread of the flue gas flow to avoid reflux, and it is also beneficial to reduce the tunnel structural damage in the condition of high temperature at the same time.