The Simulation And Analysis Of Fire Smoke Of Extra Long Tunnel In High Altitude Region

By the development of railway construction, the scale and number of tunnels had been increasing. Tunnels longer than 10km, which was called "Long Tunnels" were constructed. As the engineering features, altitude of many railway tunnels were higher than 3000m, which are called "High-altitude Tunnel". For example, Guanjiao tunnel is 32.645km long. The altitude of the tunnel entrance and the exit is higher than 3000m. So Guanjiao tunnel contain the feature of "extra long" and "high altitude". As the complexity of disasters and environmental conditions, long tunnel and high-altitude tunnel disaster prevention and emergency rescue had become a difficult and critical factor to the safe operation of the tunnel. Of all the disaster affecting the safe operation of the tunnel, fire hazard occurred in the tunnel is the most serious one. The background of this paper is "high-altitude long tunnel disaster prevention and emergency rescue technology", which is the key research subject of Ministry of Railways. Guanjiao Tunnel in Qinghai-Tibet Railway is the main research object.Research status of the fire security on the long tunnel and high altitude are introduced at home and abroad; the impact factor of long and high altitude tunnel fire safety are summed up; the common methods of numerical simulation of fire are introduced. A mathematical model is established in term of the equation of mass balance, the equation of momentum balance, the equation of energy balance, the equation of heat conduction and turbulence equation. Boundary conditions and initial conditions data needed by the numerical simulation are got by field test. The CFD software Star CCM+ was used to establish the geometric model and physical model, the buoyancy-modified k-εmodel was used in the simulation of fire and the standard k-εmodel was used in the simulation of ventilation. Results showed that, parts of the passengers in the emergency station were not safe, improvement on ventilation and smoke discharge model was needed; security of passengers in the state of randomly rescue was assured; the option with 4 jet fans in each group was better than the option with 6 jet fans. Conclusions above were helpful to the security of the passengers, arrangement position of fans and optimal designing of the emergency station.