铁路隧道火灾烟气温度场分布规律的试验研究

Experimental study on the temperature distribution of fire-induced smoke in railway tunnel fires

以我国某铁路水下盾构隧道为背景,针对不同纵向通风风速、火灾规模等因素进行了18组缩尺寸火灾模型试验,对火灾时隧道内烟气温度场的纵向变化规律、高温烟气的蔓延规律进行研究,获得了不同工况下拱顶下方烟气温度纵向分布规律、火区内和火区下游烟气最高温度分布规律,以及火灾蔓延范围等。并根据火区内烟气最高温度的试验数据,得到关于烟气最高温度与纵向通风风速及火灾规模的理论公式。拟合结果表明,该理论公式与试验数据能够较好地吻合,相关性为0.92左右。

The present paper intends to introduce our experimental study on the temperature distribution of fire-induced smoke in railway tunnel fires. In order to provide appropriate fire rescue measures and diminish the damage caused by the fire, we have carried out eighteen tests in a reduced-scale model tunnel in hoping to trace the distribution of smoke temperature along the tunnel ceiling and the high-temperature smoke dispersing regularity in the tunnel. On the basis of studying the first extra-long underwater railway tunnel in China, we have traced the longitudinal ventilation velocity with the variation of the fire size. From the tests we have found the smoke temperature below the tunnel ceiling in diverse situations, the maximum smoke temperatures below the ceiling at the near-fire position and the downstream situation, in addition to the distribution range of given smoke temperatures under the ceiling. The results of our study show that the decreases of smoke temperature along the tunnel ceiling at different longitudinal ventilation velocities and fire sizes can fall into an exponential function. The smoke temperatures for the upstream back layering prove to be more sensitive to the longitudinal ventilation. At the lower wind velocities, the smoke temperature below the ceiling for the upstream back layering tends to be higher at the near fire positions while decreasing faster when travelling away from the fire than that of the downstream fire current. However, when the longitudinal ventilation velocity is not lower than the critical one, the smoke temperature won＆rsquo;t be rising. The maximum smoke temperature below the tunnel ceiling should be lower with the higher longitudinal ventilation velocity, but higher with larger fire size. In addition, we have obtained an exponential expression about the relationship among the maximum smoke temperature, longitudinal ventilation velocities and the fire sizes based on the experimental data measured. And the predictions of the formula prove to be in concord with the experimental data for all the tests with a correlation coefficient of 0.92.