隧道火灾临界风速模型的差异与适用性分析  

Analysis of differences and feasibility of critical velocity models for tunnel fires

作　　者：孙峰[1] 李江栋 王小飞[1] 吴珂[2,3,4] Sun Feng;Li Jiangdong;Wang Xiaofei;Wu Ke(China Railway Siyuan Survey and Design Group Co.,Ltd.,Hubei Wuhan 430063,China;Center of Balance Architecture,Zhejiang University,Zhejiang Hangzhou 310037,China;Key Laboratory of Offshore Geotechnics and Material of Zhejiang Province,Zhejiang University,Zhejiang Hangzhou 310058,China;Research Center for Urban Fire Safety Engineering,Zhejiang University,Zhejiang Hangzhou 310058,China)

机构地区：[1]中铁第四勘察设计院集团有限公司,湖北武汉430063 [2]浙江大学平衡建筑研究中心,浙江杭州310037 [3]浙江大学浙江省海洋岩土工程与材料重点实验室,浙江杭州310058 [4]浙江大学城市火灾安全工程研究中心,浙江杭州310058

出　　处：《消防科学与技术》2024年第9期1272-1277,共6页Fire Science and Technology

基　　金：宁波市交通科技计划项目(202113);浙江省重点研发项目(2018C03029);杭州市人工智能关键技术研发计划(2022AIZD0057)。

摘　　要：临界风速是纵向通风隧道防排烟设计的重要指标,目前广泛采用的临界风速模型分为临界弗洛德数模型(世界道路协会PIARC推荐)和分段函数模型(美国消防协会NFPA推荐)两类,但两种公式的计算结果差异显著,给隧道防火设计造成了困扰。本文分析了PIARC公式和NFPA公式在不同火源功率、隧道宽度、隧道高度下计算临界风速的差异及成因,同时结合隧道火灾全尺寸试验、数值模拟对比了两种公式计算结果的控烟效果,并与已有的全尺寸和比尺模型试验数据比较论证了两公式的适用性。结果表明,受临界弗洛德数取值和均匀混合假定的制约,PIARC公式无法准确反映临界风速随火源功率的变化规律,公式计算结果明显偏小,且误差随着宽高比的增大而增大;而NFPA公式更加全面地考虑了火羽流状态与隧道断面尺寸之间的相对关系对临界风速的影响,计算结果具有更好的烟气控制效果,且与试验数据更为吻合;NFPA公式可以适用于大部分隧道断面和火源功率条件下的临界风速计算,而PIARC公式仅适用于断面宽高比较小(AR≤1)和火源功率较大(HRR≥15MW)时的临界风速计算。Critical velocity is an important indicator of the smoke control design for longitudinal ventilation tunnel fires.Currently,two calculation methods,i.e.,the critical Froude model(recom-mended by the World Road Association,PIARC)and the piece-wise function model(recommended by National Fire Protection Association,NFPA)are widely adopted in practice.Neverthe-less,the calculation result of the two models shows a significant difference,causing confusion and disagreement regarding tunnel fire safety design.This work analyzes the differences between the PIARC equation and the NFPA equation under various heat re-lease rates,tunnel widths,and tunnel heights,respectively and the reasons are discussed in detail.Then,the smoke control per-formances and feasibilities of these two models are compared with a set of numerical simulations,full-scale and reduced-scale test data.Results show that the PIARC equation fails to describe the correlation between critical velocity and heat release rate due to the fixed Frc value and unrealistic uniform mixing assumption.The PIARC equation will underestimate the critical velocity and the error increases with the tunnel aspect ratio.The NFPA for-mula comprehensively considers the impact of the relationship be-tween the fire plume and the tunnel structure on critical velocity.Therefore,the prediction shows a better smoke control perfor-mance and agrees well with physical test data.Moreover,realistic factors,e.g.,blockage,altitude,fire source rising,and lateral lo-cations will also affect the value of critical velocity and should be considered in future work.

关 键 词：隧道火灾 纵向通风 临界风速 全尺寸试验 数值模拟 适用性 

分 类 号：U452[建筑科学—桥梁与隧道工程]