对于浅埋竖井型城市公路隧道（URTS），在火灾发生时烟气依靠自身热浮力排放，但实际排烟情况却存在着不确定性。为研究夏季隧道主体烟流扩散特性与竖井排烟性能，于2019年对南京2条URTS隧道实施了3次不同着火点的1.58 m×1.58
m柴油火试验，测得了顶棚下方、多个竖井顶/底部的烟气参数，发现近火源竖井单元有显著排烟，其最大排烟温度为47 ℃、速度为5 m/s、CO体积分数为18×10-4； 而远火源竖井单元底部烟气倒灌严重。进一步的分析结果表明： 1)顶棚下方烟流纵向温度/速度分布符合幂指数衰减规律，衰减系数较大程度受季节、着火位置、火源上下游影响； 2)实测竖井单元排烟量随远离火源逐次下降，已有排烟量预测模型未考虑烟流倒灌现象与烟气参数不均匀性； 3)试验1和试验2中的6#竖井Ri′分别达到10.8和1.5，已有Ri′c =1.4模型不适用于评价倒灌竖井底部烟流状态。
彭涛
,
童艳
,
张广丽
,
龚延风
,
陈征
,
郭屹忠
,
茅钦
,
吕刚玉
,
黄伟浩
,
戴宝连
. 夏季火灾工况下城市公路隧道竖井自然排烟现场试验研究[J]. 隧道建设, 2023
, 43(7)
: 1170
-1179
.
DOI: 10.3973/j.issn.2096-4498.2023.07.010
In case of fire,
the smoke is discharged by its thermal buoyancy for shallowburied
urban road tunnels with vertical shafts,
but the actual smoke exhaust situation remains unclear. To examine the
smoke diffusion characteristics of the tunnel main body and the smoke exhaust
performance of the shaft in summer,
three 1.58 ×1.58 m2
diesel fire experiments with different ignition points were conducted in two
tunnels in Nanjing in 2019, where the
smoke parameters under the ceiling and at the top/bottom of several shafts are
measured. It was found that the shafts near the fire source had substantial
smoke exhaust, with a maximum smoke
exhaust temperature of 47 ℃, a speed of 5 m/s, and a CO volume fraction of 18×10-4 , whereas shafts far from
the fire source had substantial backward smoke flow. The following are the
results of the analysis: (1) The longitudinal temperature/velocity distribution
of smoke flow under the ceiling obeys the law of power exponent attenuation, and the attenuation coefficient is
significantly influenced by the season,
the ignition position, the
upstream, and the downstream. (2) The
measured smoke exhaust of the shaft decreases gradually as the distance from
the fire source increases, and the
existing prediction models for smoke exhaust does not consider the backward
flow and uneven distribution of smoke. (3) The 〖WT5BX〗Ri′〖WT５《TNR》〗 number of the #6 shaft in the Shuiximen tunnel reaches 10.8 (Test
1) and 1.5 (Test 2), respectively, and the existing model with 〖WT〗Ri′c〖WT５《TNR》〗=1.4 is
unsuitable for evaluating the smoke flow state at the bottom of the shaft.
