高海拔隧道防烟策略及疏散通道间距探讨

为了确定高海拔环境下特长公路隧道的服务隧道防烟通风策略及人员疏散通道最佳间距,采用FDS和Pathfinder建立了主隧道+服务隧道的通风排烟及人员疏散仿真模拟平台,分析50 MW火灾规模下隧道内烟气运动规律及人员疏散过程,基于克拉尼公式和FED准则综合判定ASET(可用安全疏散时间)。针对低氧气环境下人员运动效率低下的这一背景情况,对人员疏散速度进行折减,进一步确定RSET(必须安全疏散时间)。结果表明:服务隧道内纵向风速1.6 m/s可保证服务隧道内1 200 s时间范围内无烟,考虑高海拔地区火灾增长系数的折减,人员可用安全疏散时间呈现为“W”形,下游200 m处可用安全疏散时间最少,结合人员必须安全疏散时间分析,人行通道间距宜设置为200 m。

Discussion on the Smoke Prevention Strategy of High-altitude Tunnel and the Evacuation Channel Spacing

In order to determine the smoke prevention strategy of service tunnel and the optimum spacing of evacuation passageways of extra-long highway tunnel in high-altitude environment, FDS and Pathfinder were used to establish a simulation platform for ventilation and personnel evacuation of main tunnel and service tunnel. The smoke movement law and evacuation process in tunnel under 50 MW fire were analyzed. The ASET (Available Safe Evacuation Time) is assured by combining Craney formula and FED criterion. Based on the background situation of low movement efficiency of personnel in low oxygen environment, the evacuation speed is reduced, and the RSET (Request Necessary Safe Evacuation Time) is further determined. The results show that: the longitudinal wind speed of 1.6 m/s in the service tunnel can ensure smoke-free in the service tunnel within 1 200 s. Considering the reduction of fire growth coefficient in high-altitude areas, the ASET is in the shape of "W", and the minimum ASET is located at 200 m downstream. The pedestrian passage spacing should be set at 200 m combined with the analysis of RSET.