Numerical Simulation Of Fire In An Inclined Tunnel With Curvature

With the continuous development of transportation,the structural forms of highway tunnels are becoming more and more diversified,and the appearance of inclined and curved tunnel overcomes the influence of geological conditions such as elevation difference and bad topography,and makes people’s transportation more convenient.In the highway tunnel development,there is the risk of tunnel fire.In recent years,there have been many major tunnel fire incidents at home and abroad,which have caused great damage to people’s lives and property.In case of fire,under the influence of slope and curvature,the velocity,direction and temperature of the smoke are more complicated than those of the straight tunnel,which makes it more difficult to rescue and escape in the tunnel.Therefore,it is of great significance to study the fire in inclined tunnel with curvature.This paper first introduces the development of tunnel construction,the damage of tunnel fire and the research status of tunnel fire at home and abroad,the process of smoke spreading in tunnel and the method of smoke control are described.Then,FLUENT numerical simulation software is used to study the smoke spreading law of slope tunnel and curved tunnel,the influence of slope and curvature on the spread of smoke in tunnel is analyzed.Finally,a three-dimensional model of inclined curvature tunnel is established,the influence of slope and curvature on the spread of smoke is analyzed and the effect of longitudinal wind on the control of fire smoke in inclined tunnel with curvature is considered,the critical wind speed under different fire power is simulated.The main research contents and results are as follows:(1)When a fire occurs in a slope tunnel,the velocity and temperature of smoke spreading in the downhill direction of the tunnel decrease with the increase of the slope,while the velocity and temperature of smoke spreading in the uphill direction of the tunnel increase with the increase of the slope.The tunnel slope ranges from 0% to 3%,the maximum temperature of tunnel vault decreases with the increase of slope,there is a critical slope value between 3 and 5% of tunnel slopes,the maximum temperature of the vault below the critical slope value decreases with the increase of the slope,the maximum temperature of the vault above the critical slope value increases with the increase of the slope.(2)When a fire occurs in a curved tunnel,the presence of the curvature of the tunnel will hinder the spread of smoke,in the vicinity of the fire source,the temperature of the tunnel vault decreases with the increase of the curvature of the tunnel.(3)This paper studies the fires with different source power in inclined curved tunnel.The results show that the higher the power of the fire source,the faster the smoke spread and the higher the temperature,under the joint action of the slope and curvature of the tunnel,the temperature of flue gas in the uphill direction of the tunnel is higher than that in the downhill direction,and the temperature in the outside of the tunnel is higher than that in the inside of the tunnel.(4)The effect of longitudinal wind on fire in inclined tunnel with curvature is considered.The results show that the higher the wind speed,the lower the temperature of the flue gas in the tunnel,the smaller the backflow of the smoke.The critical wind speeds of 5,10 and 20 MW are 2.2,2.7 and 3.0m/s,respectively.