【作者】 吴德兴；

【导师】 何川；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 近年来,随着我国各类特长公路隧道的大量涌现,隧道内火灾事故的危险性亦呈上升趋势,论文在充分调研分析国内外特长公路隧道通风排烟设计经验的基础上,结合浙江省特长公路隧道的具体特点,采用数值模拟、理论分析及模型试验等手段对火灾条件下有独立排烟道的点式通风排烟模式进行了全面系统地研究,取得的研究成果主要包括：1、基于对世界范围内特长公路隧道通风排烟系统设计资料的分析及对不同通风排烟模式的综合比较研究,根据现今纵向通风模式下三种独立排烟道系统的各自特点,结合浙江省境内特长公路隧道坡度长、交通量大、行车组织复杂及高于全国平均水平的火灾发生频率等具体特征,经过经济、技术及安全等各方面综合比较后,在山岭隧道中提出了火灾条件下开启有独立排烟通道的点式排烟系统,正常运营时竖井送排式与射流风机相结合的纵向通风模式的设计理念。2、通过对特长公路隧道有无排烟道火灾时通风排烟系统的三维数值模拟分析,研究对比了上述两种不同通风排烟模式下火灾发生时温度场分布及火灾烟气蔓延规律,验证了在有独立排烟道点式通风排烟模式下火灾发生时,火灾烟气的影响范围可控制在较小区域内；能有效解决单洞双向交通火灾、二次事故火灾、“烟囱效应”不利影响,可有效控制烟气蔓延及沉降,提高防灾救援安全性等优点。同时从火灾时的“烟囱效应”的影响分析来看,有独立排烟道时,火灾时“烟囱效应”引起的烟雾基本在排烟道内流动,人员及车辆可安全撤离。且能有效降低二次衬砌的拱顶最高温度值,对于二衬营运期间火灾条件下的安全性起到保护性作用。对于特长公路隧道采用该通风排烟方式提供了有力的理论依据。3、通过模型试验手段对有独立排烟道点式排烟模式下不同工况时温度场分布特征、火灾烟气蔓延规律、合理诱导风速的深入研究,探明了该通风排烟模式下坡度对高温区分布范围及烟气蔓延的影响特点,进一步对比了火灾发生时单双向排烟在烟气控制效果方面的优劣性,并根据研究成果,修正了坡度条件下的“临界风速”理论计算公式,揭示了坡度变化对合理诱导风速的影响特征,提出了不同坡度下火源位于排烟阀不同位置处的合理诱导风速值及风向选择,试验成果在进一步补充完善数值分析结论的基础上,验证了其准确性,对于后期将此通风排烟设计理念应用于特长公路隧道工程提供了重要的理论依据。4、通过模型试验手段对点式排烟模式下隧道排烟道内及排烟阀处的烟流分布规律、排热效果及排烟系统合理设置方式进行系统地分析研究表明：隧道排烟道内及排烟阀处烟气流速按照距离排烟风机由近至远呈递减趋势,双向排烟时排烟道内及排烟阀处最高烟气流速要小于单向排烟,排烟阀最高流速与排烟阀开口总面积、单个排烟阀开口面积以及排烟阀开启间距等因素有关；建立了独立排烟道系统的流速与压强理论预测模型；排烟阀排热效率因排烟方式不同而呈现不同的分布特征,总体而言,双向排烟方式下排烟风机排热效率高于单向排烟方式,并进一步探明了影响排烟系统设置的各主要影响因素,据此提出了独立排烟道点式排烟模式下排烟系统合理设置方案,细化了排烟组织设计,为后期类似工程设计提供了关键性指标参数。更多还原

【Abstract】 In recent years, with the abundant appearance of various extra-long road tunnels in China, the risk of tunnel fire is increasing. Based on fully investigating ventilation system design of extra-long road tunnel at home and abroad, considering the characteristics of the extra-long road tunnel in Zhejiang province, a new design concept is introduced to a tunnel in Zhejiang province. Point smoke extraction system in the tunnel with independent smoke exhaust duct is studied using numerical simulation, theoretical analysis and model experiment. The main results are as follows:1. Smoke exhaust system designs of extra-long road tunnels over the world are analyzed, and different smoke exhaust systems are compared. Three independent smoke exhaust duct systems under longitudinal ventilation have respective characteristics, and the extra-long road tunnel in Zhejiang province has long slope, high traffic volume, complex traffic organization and higher fire frequency than national average. Through comparative analysis of different smoke extraction systems in economic, technical and safety aspects, the design concept that point smoke extraction system with independent smoke exhaust duct in fire conditon and longitudinal ventilation system consisting of shafts and jet fans in normal condition is proposed in mountain tunnel.2. When a fire occures, the smoke extraction systems in tunnel with and without smoke duct are analyzed through three-dimensional numerical simulation, and temperature distributions and fire-induced smoke movements in tunnel with the two smoke exhaust systems above are compared. It can be seen that when fire occurs in tunnel using point smoke extraction system with independent smoke duct, smoke can be controlled in limited area, and the adverse impact of two-way tunnel fires with uni-or bi-direction traffic secondary fires by incidents and chimney effect can be well controlled. In addition, smoke is distributed in upper part of driveway and controlled effectively, and it is safer to rescue and evacuate. At the same time, fire-induced smoke mainly spread in smoke duct under the influence of chimney effect, so passenger and drivers can escape safely, and the maximum smoke temperature below ceiling is decreased. Theoretical basis is provided for extra-long road tunnel using the smoke exhaust sy.stem.3. The characteristics of temperature distribution, smoke spread and induced wind speed under point smoke exhaust mode in tunnel with independent smoke exhaust duct are studied through model experiments. The influence of tunnel slope on high temperature range and smoke spread is explored, and the effectiveness of smoke control under unidirectional and bi-directional exhaust mode are compared. According to the test results, the formula of critical wind speed in slope condition is modified, and the impact of slope change on induced wind speed is revealed. The selection of induced wind speed and wind direction under different tunnel slopes and different ignition source positions was raised. The numerical simulation results are complemented and verified by experiment results and it can provide theoretical basis for ventilation and exhaust design of extra-long tunnels.4. The research on smoke distribution, heat extraction effectiveness and exhaust system setting under point smoke exhaust mode shows that:smoke flow velocity in smoke exhaust duct and at exhaust valves decreases when the distance from the exhaust fan increases; the maximum smoke flow velocity under bi-directional exhaust mode is less than that under unidirectional exhaust mode; the maximum smoke flow velocity is related to total area of exhaust valves, area of each valve and space between different valves; the theoretical model of flow velocity and pressure intensity of independent smoke exhaust duct system is established; different smoke exhaust modes have different distribution characteristics of heat extraction efficiency; in general, the heat extraction efficiency of exhaust fans under bi-directional exhaust mode is higher than that under unidirectional exhaust mode; the main factors that influence the smoke exhaust system are ascertained, according to which proper setting scheme of exhaust system under point smoke exhaust mode in tunnel with independent smoke exhaust duct is proposed and smoke exhaust organization design is specified; it can provide key index parameters for similar engineering designs.更多还原