考虑时间因素的铁路隧道防灾通风方案研究

Study of Fire Ventilation Scheme for Railway Tunnels Considering Time Factor

研究目的:隧道防灾通风系统启动后,疏散横通道防护门不能立刻达到临界风速,尚需等待一定的时间。现行铁路防灾规范要求安全疏散时间不宜超过6 min,可见疏散前期的时间是十分宝贵的,防灾通风系统的及时性是必须考虑的问题。基于此,本文研究两单隧道互为救援时的防灾通风系统,建立防灾通风网络模型,从整体上对救援站供风策略开展对比分析,另外也对目前广泛采用的安全隧道供风的漏风率进行研究。研究结论:(1)安全隧道供应新鲜风时,普通横通道防护门门缝存在漏风,漏风率随隧道长度增加而增大,隧道长度超过36 km且门缝大于4 mm时,将有超过10%的新鲜风在送往救援站的途中损失;(2)应关注救援站防护门处风速的时变特性,以快速达到并保持不小于临界风速表征通风方案具有良好的及时性;(3)由安全隧道供风的方案,防护门处风速时变模式记为M1,该风速随时间单调增大并可划分3阶段,即初期缓慢增大、中期快速增长、后期持续缓慢增大并趋稳定;由辅助坑道供风的方案,防护门处风速时变模式记为M2,该风速峰值出现在疏散前期,可划分3阶段,即初期缓慢增大、中期快速增大并出现最大值、后期持续缓慢降低;相较而言,M2具有更优的及时性;(4)隧道内火灾可用疏散时间短,救援站防护门处风速及时达到临界风速,对于保障人员安全具有重要意义,该研究成果可为工程方案选择提供参考和借鉴。

Research purposes:After the tunnel disaster prevention ventilation system is started,the protective door of the evacuation cross passage cannot reach the critical wind speed immediately,and it needs to wait for a certain time.The current railway disaster prevention regulations stipulates that the required safety egress time should not exceed 6 minutes.The time in the early stage of evacuation is very valuable,the timeliness of the fire ventilation system must be considered.Based on these,this paper studies the fire ventilation system of twin single-track tunnel tubes.By establishing a ventilation network model,the paper conducted a comparative analysis of two ventilation strategies and studied the air leakage rate of the currently widely used air supply scheme through safe tunnel.Research conclusions:(1)When fresh air is supplied through the safe tunnel,there is air leakage due to the protection door of the ordinary cross passage.The air leakage rate increases with the increase of the tunnel length.When the tunnel length exceeds 36 km and the door gap is greater than 4 mm,more than 10%of the fresh air will be lost on the way to the rescue station.(2)The available evacuation time for tunnel fire hazard is short.Attention should be paid to the time-dependentair speed at the protection door of the rescue station.Rapidly reaching and maintaining above the critical speed indicates better timeliness.(3)When fresh air is supplied through the safe tunnel,the air speed at the protection door monotonously increases over time.Recording its air speed time-varying mode as M1,there are three stages:slowly increasing in the initial stage,rapidly increasing in the intermediate stage,slowly increasing and approaching to a stable value in the later stage.When fresh air is supplied through the auxiliary tunnel,the peak of air speed at the protection door occurs in the early stage of evacuation.Recording its air speed time-varying mode as M2,there are three stages:slowly increasing in the initial stage,rapidly increasing and reaching the peak in the intermediate stage,slowly decreasing in the later stage.The latter indicates better timeliness.(4)The fire evacuation time in tunnel is short,and the wind speed at the protective door of rescue station reaches the critical wind speed in time,which is of great significance for the safety of personnel.The research results can provide reference for the selection of engineering schemes.