The maximum ceiling temperature and longitudinal temperature distribution were investigated in bifurcated tunnels with different bifurcation angles under longitudinal ventilation. A series of experiments were carried out in a 1:10 small-scale bifurcated tunnel with a bifurcation angle of 60°, considering different longitudinal fire locations. Furthermore, 44 cases including 2 fire locations with bifurcation angles between 20°∼90° were simulated by FDS. The results indicated that: (1) The longitudinal fire location would affect the maximum temperature rise in the bifurcated tunnel. When the fire was in the bifurcated zone, the maximum temperature was lower than that in the non-bifurcated zone under a same condition. (2) The bifurcation angle had little effect on the maximum ceiling temperature. (3) The longitudinal temperature distribution of the main tunnel in the downstream from the fire source was independent of the bifurcation angle, while the attenuation rate of longitudinal temperature of the branch tunnel increased with the increasing of bifurcation angle. In addition, prediction models of the maximum ceiling temperature rise and the longitudinal temperature distribution in the main tunnel and branch tunnel were proposed, which could well predict the smoke temperature profile in T-shaped bifurcated tunnels with bifurcation angles between 20° and 90° under the dimensionless ventilation velocity greater than 0.19.

研究了纵向通风下不同分岔角分岔隧道的最高顶板温度和纵向温度分布。考虑不同的纵向火灾位置，在分叉角为60°的1:10小比例分叉隧道中进行了一系列实验。此外，通过FDS模拟了44个案例，包括2个分岔角在20°~90°之间的火灾位置。结果表明：(1)纵火位置会影响分岔隧道的最大温升。火灾发生在分叉区时，在相同条件下，最高温度低于非分叉区。(2) 分岔角对最高顶棚温度影响不大。(3)火源下游主隧道纵向温度分布与分岔角无关，而支隧道纵向温度衰减率随着分岔角的增大而增大。此外，提出了最大顶棚温升和主支隧道纵向温度分布预测模型，可以较好地预测分叉角在20°~90°之间的T形分叉隧道的烟气温度分布。无量纲通气速度大于 0.19。