Research On High Altitude Railway Tunnel Emergency Rescue Station Fire Combustion Characteristics And ASET Computational Model

With the advancement of the new round of Western Development and the rapid development of infrastructure,a large number of high-altitude railway tunnels have emerged in China.Although the construction of railway tunnels has promoted ecnomic development and brought convenience to our production and life,the railway tunnels are prone to accidents such as running,train shutdown and during operation.If a tunnel fire occurs,it will cause casualties,economic losses and social panic.Due to the environment characteristics of‘low temperature,low oxygen and low pressure’ in high altitude railway tunnels,the fire characteristics are different from those in plain tunnels.At this point,evacuation mainly depends on ermergency rescue stations.Therefore,the study on the combustion characteristics of the emergency rescue station of the high-altitude railway tunnel and the available safe evacuation time calculation model is of great significance to the disaster prevention and rescue design of the high-altitude railway tunnel.The research methods in this paper include literature survey method,CFD(Computational Fluid Dynamics)numerical simulation,orthogonal test principle,range analysis,regression analysis and theoretical derivation,etc.In this paper,the characteristics of railway tunnel fires and the characteristics of high altitude environment are introduced.The fire and combustion characteristics of the emergency rescue station of the high-altitude railway tunnel and the safe evacuation time of personnel were studied.The article gives the recommended values for the structural parameters of smoke extraction facilities at different altitudes.This article mainly leads to the following conclusions:(1)The characteristics of fire flue gas spread and the distribution of temperature field at the emergency rescue station of high-altitude railway tunnel were investigated.Through comparative analysis,the fire combustion characteristics at different altitudes were obtained when the scale of the fire source was 20 MW.When the scale of the fire is the same,with the increase of altitude,the spread rate of fire smoke increases,the smoke production of the fire increases,and the longitudinal spread rate accelerates,and the maximum temperature of the vault at the source of the fire increases.At a certain altitude,with the increase of the wind speed of the exhaust outlet,the flue gas spread distance decreases,and the maximum temperature of the vault at the source of the fire decreases.When the exhaust outlet wind speed is greater than 4m/s,the phenomenon of flue gas subsidence begins to decrease.When the spacing between the exhaust outlets changes,the larger the spacing between the exhaust outlets,the lower the efficiency of the exhaust,and the temperature of the vault at the source of the fire increases.When the spacing between the exhaust ports is 120 m,the smoke extraction efficiency is greatly reduced.When the area of the exhaust outlet changes,the larger the area of the exhaust outlet,the better the smoke exhaust effect,but the overall temperature and flue gas concentration in the tunnel do not change much.(2)This article is based on the principle of orthogonal test,the working condition table of the 4-factors 4-levels’ available safety evacuation time calculation model is established.The extent to which influencing factors affect the available safe evacuation time can be obtained by measuring the difference analysis.The results of the range analysis are as follows: altitude> exhaust air velocity> smoke outlet spacing> exhaust area.Through the regression analysis of the orthogonal experimental results,an available safe evacuation time calculation model for the emergency rescue station of the high-altitude railway tunnel was obtained(3)This article is based on the safety evacuation criteria of personnel and the calculation model of available safe evacuation time,this chapter establishes a flowchart of structural parameters of smoke exhaust facilities at emergency rescue stations in highaltitude railway tunnels.Through the flow chart,the recommended values of the structural parameters of the smoke exhaust facilities of the emergency rescue station of the railway tunnel at different altitudes are given.