| Under the background of the construction of Sichuan Tibet railway,the height and length of railway tunnels in China will create new records.However,the research on the train fire and evacuation rescue of the corresponding high-altitude super long tunnel is not sufficient,and many fields are still blank.Based on the fund project of China Academy of Railway Sciences Group Co.,Ltd.(2019yj027),taking the high altitude tunnel fire as the research object,this paper puts forward five potential disaster causing factors and their warning values,selects the numerical simulation software FDS,adopts the large eddy simulation and the mixed fraction model In this paper,the fire smoke spreading rule and evacuation safety of four kinds of fire carrying trains and 14 kinds of emergency rescue stations are analyzed,the disaster causing factors and mechanism of high altitude tunnel fire are analyzed,and the smoke control of some articles in the current Code for Design of Rescue Engineering for Disaster Prevention and evacuation of Railway Tunnel(TB10020-2017)at high altitude is discussed.The main conclusions are as follows:(1)Five potential hazard factors and their hazard warning values during high-altitude tunnel fires are proposed,especially for the low-oxygen characteristics of the environment in high-altitude tunnels,and "oxygen concentration" is included in the potential hazard factors.The results show that the too low oxygen concentration in the fire site is a unique hazard factor for high altitude railway tunnel fires,and is an important feature that is different from ordinary altitude tunnel fires.However,the current specifications are not included,and it is recommended to increase the "oxygen concentration not less than 14% ".(2)When the fire-carrying train is randomly stopped at a non-rescue station,if there is no longitudinal ventilation,the smoke spread at each time of 3500 m above sea level at 500 m above sea level will extend longer and spread faster.The fire was 7.0% faster at 30 s and 0.3% faster at 270 s.In addition,the fire source will enter a smoldering state at an altitude of 3500 m,which has a great influence on the vertical settlement of flue gas,and the flue gas layer fluctuates significantly;when the critical wind speed is applied,there is little difference between the vertical spread and vertical settlement at two altitudes.When considering the application of longitudinal wind from the evacuation safety,the available safety evacuation time downstream of the fire source is greatly reduced,that is,the longitudinal wind should be applied carefully.When there is no longitudinal ventilation,when the distance between the horizontal channels is less than 145 m,all personnel can be evacuated safely.(3)When a fire-carrying train is docked at an emergency rescue station,if no smoke control is applied,the smoke at high altitude will spread faster in the accident tunnel,but the spread in the contact flue is similar.Not big.When smoke is ventilated and exhausted according to the type of rescue station,the spread of smoke in different types of rescue stations and smoke exhaust methods is quite different.According to the smoke control effect,it is recommended to set up the main shaft in the emergency rescue station in the tunnel in combination with the inclined shaft.In the event of fire,centralized smoke exhaust is preferred.(4)The evacuation safety research results of high altitude emergency rescue station fire show that: the wind speed of 2.0m/s at the protective door of the cross passage can ensure that the cross passage is a safe area;but it is recommended to 5.3.1 in the " Code for Design of Rescue Engineering for Disaster Prevention and evacuation of Railway Tunnel " Section 3,"The supplementary air volume should not be less than 50% of the exhaust volume" to be revised.The current percentage of supplementary air volume should be increased,and the specific percentage needs to be further studied.There are 116 pictures,27 tables and 97 references. |
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