Slope On Long Highway Tunnel Fire Smoke Spread Characteristics Of Impact Studies

With the rapid development of highway construction in recent years, extra-long highway tunnels emerge in large numbers, which brings a great challenge to the fire protection of tunnels. In this dissertation, theoretical analysis, reduced scale model tests and numerical simulation have been used to study the characteristics of chimney effect and the influence of slope on smoke spread, which is essential to the fire protection of extra-long road tunnels. The following works have been accomplished:(1) Based on theoretical analysis, a theoretical model has been established to analyze the influence of slope on vertical temperature distribution and buoyant smoke flow resistance in tunnels. Then the influence of slope on vertical temperature distribution and buoyant smoke flow resistance has been investigated.(2) The influence of slope on temperature distribution and buoyant smoke spread in tunnels has been studied through reduced scale model tests. The slope condition that forms chimney effect has been obtained, and also the influence of slope and ignition source on the intensity of chimney effect has been acquired.(3) As a supplement of model tests, numerical simulation has been used to study the influence of slope on smoke temperature distribution and smoke development in tunnel fires. The distributions of smoke temperature of near fire source, longitudinal direction and cross-sectional direction have been acquired, the flow velocity distribution of upslope and smoke development of downslope have been obtained. And the results derived from numerical simulation and model tests have been compared.(4) The influnence of slope on smoke development and the characteristics of chimney effect in tunnel fires under different smoke exhaust modes have been studied through numerical simulation. The distributions of smoke temperature, flow velocity in driveway and shaft have been acquired under different smoke exhaust modes, tunnel slopes and shaft heights. The influence of tunnel slopes and the characteristics of chimney effect under three familiar smoke exhaust modes have been compared.The research results of this dissertation can provide valuable technical reference and scientific basis for smoke control, and ventilation and smoke exhaust design of extra-long highway tunnels.