Combustion characteristics and flame morphological evolution of double-layer cable fires in urban utility tunnels with various laying spacings

作者：Desheng Xu, Yanfeng Li, Junmei Li, Hua Zhong, Jiaxin Li, Youbo Huang · 发表于：Energy · 年份：2025 · DOI：10.1016/j.energy.2024.134324 · 被引用次数：18 · 研究领域：Fire dynamics and safety research、Fire effects on ecosystems、Evacuation and Crowd Dynamics

Utility tunnels serve as critical infrastructure for urban energy and electricity transport systems, housing multi-layered cable arrangements that pose significant fire hazards. This study investigates the effects of cable arrangement and layer spacing on the combustion parameters and flame evolution of double-layer cable fires, emphasising their implications for energy infrastructure safety. Using a reduced-scale utility tunnel model, we conducted fire experiments to measure the heat release rate (HRR), oxygen consumption, and fuel energy of cable combustion. The key parameters evaluated were the cable fuel energy, surface temperature, pyrolysis efficiency, and flame morphology. Our findings indicate that both total combustion time and HRR decrease with increasing layer spacing. Notably, the pyrolysis efficiency of double-layer cable fires can exceed 100 %, reaching up to 110 % at a spacing of 1 cm due to the mutual fuel effect created by the close proximity of the layers. This effect enhances the fire intensity, illustrating how the layer spacing critically influences the combustion dynamics. When the layer spacing exceeds the critical threshold, the lower cable cannot ignite the upper cable, resulting in a single-layer fire scenario. Additionally, the flame characteristics are positively correlated with increased HRR and reduced layer spacing. We analytically delineated the critical layer spacing into three distinct regions and proposed novel mathematical models to quantif...