The interaction between multiple fires is complex, in which the theory of single fire is not applicable. This study focuses on the combustion characteristics and temperature distribution of two pool fires with different transverse locations in a model tunnel under natural ventilation. In this study, 84 groups of combustion experiments of two ethanol pool fires were designed by varying the spacing between two pool fires (denoted by S), transverse distance between the geometric center of pool fires and tunnel sidewall (L), and side length of oil pan (D). The experimental results show that when L = 50 cm and L = D/2, mass loss rate decreases along with a bigger S/D, and reaches the minimum for L = 50 cm and the maximum for L = D/2. However, mass loss rate first increases and then decreases with S/D for L = 30 cm and L = 20 cm, which is controlled by the competition between air entrainment and radiant heat feedback. In order to describe the influences of fire source spacing and transverse distance, a prediction model of maximum temperature rise under the tunnel ceiling is developed, which matches the experimental results well. Under the case of no flame merging, longitudinal temperature distribution is insensitive to the transverse location rather than the spacing between the fire sources. Moreover, it is found that the vertical temperature distribution far from the fire sources matches the Gaussian distribution well. The results of this work can provide a significant reference for the risk assessment of tunnel fires with two fire sources.

多火相互作用复杂，单火理论不适用。本研究重点研究自然通风条件下模型隧道内两种不同横向位置的池火的燃烧特性和温度分布。本研究通过改变两池火之间的间距（用S表示）、池火几何中心与隧道侧壁之间的横向距离（L）和边长，设计了 84 组两种乙醇池火的燃烧实验。油底壳 ( D )。实验结果表明，当L =  50 cm 且L  =  D /2 时，质量损失率随着S的增大而减小/ D，并在L  = 50 cm 时达到最小值，在L  =  D /2 时达到最大值。然而，对于L  = 30 cm 和L，质量损失率随S / D先增加后减小 = 20 cm，这是由空气夹带和辐射热反馈之间的竞争控制的。为了描述火源间距和横向距离的影响，建立了隧道顶棚下最大温升预测模型，与实验结果吻合较好。在不合并火焰的情况下，纵向温度分布对横向位置不敏感，对火源间距不敏感。此外，发现远离火源的垂直温度分布与高斯分布很好地匹配。研究结果可为双火源隧道火灾风险评估提供重要参考。