Study Of Smoke Characteristics And Safe Evacuation Of Road Tunnels In Extra-high Alititude Area

With the development of the western region,the number of tunnels in extra-high altitude is increasing.The area of Extra-high altitude has the characteristics of thin air,cold temperature,low oxygen and low pressure.These environmental characteristics put forward a new topic for disaster prevention and evacuation of highway tunnels.With the increase of altitude,the combustion characteristics,smoke diffusion mechanism and evacuation activities of tunnel fire are greatly changed compared with plain areas.Due to the particularity of extrahigh altitude and the scarcity of related research,it is necessary to study the smoke characteristics and evacuation technology of ultra-high altitude highway tunnel fire.Aiming at the highway tunnel fire in extra-high altitude,The main research work and achievements of this paper include the following three aspects:1.The smoke characteristics of highway tunnel fire in extra-high altitude were studied by the scale tunnel model test designed as a mobile test platform at different altitudes,including the heat release rate of fuel,vertical temperature distribution of smoke and concentration of carbon monoxide.Considering the influence of environmental parameters in high altitude area,the fitting relationship of altitude to the ratio of fire heat release rate and the fitting relationship of altitude to the ratio of concentration of carbon monoxide under unit mass loss rate are proposed.2.The diffusion mechanism of fire smoke in extra-high altitude highway tunnel is analyzed by numerical model calculation,and the effects of altitude and fire scale on the temperature field distribution,CO concentration field distribution and visibility change at the crown and characteristic height(2m)of fire smoke are explored.Some data are used to calculate the safe evacuation of fire personnel.3.Based on the influence of altitude,personnel characteristics and fire products on human movement speed,the evacuation characteristics of highway tunnel in extra-high altitude are revealed by using simulation software.Combined with FED model,the fire environment control standard for judging personnel safety is proposed.Finally,the optimal design of cross passage spacing of highway tunnel in extra-high altitude is given.In order to ensure the safe escape of tunnel personnel under the condition of fire,the dynamic characteristics of fire smoke and personnel evacuation in ultra-high altitude highway tunnel were studied.This is of great significance to improve the theoretical level of highway tunnel fire research in extra-high altitude in China,and provides a scientific basis for the design of disaster prevention ventilation system and the improvement of personnel evacuation scheme in ultra-high altitude highway tunnels in China.