@article{XU2026, 
author = {Desheng XU and Yanfeng LI and Yong XU},
title = {Study on the influence of slope and ventilation compartment length on cable fire development in utility tunnels},
year = {2026},
journal = {Experimental Technology and Management},
volume = {43},
number = {1},
pages = {44-50},
keywords = {underground space, utility tunnel, cable fire, fire spread},
url = {https://www.sciopen.com/article/10.16791/j.cnki.sjg.2026.01.006},
doi = {10.16791/j.cnki.sjg.2026.01.006},
abstract = {ObjectiveThe continuous expansion and intensification of urban underground space utilization are leading to increasingly complex utility tunnel designs, including structures with significant longitudinal slopes and extended ventilation compartments. In contrast to cable fires in conventional utility tunnels, the interaction between slope-induced airflow and ventilation airflow path creates a unique underground environment that significantly affects fire spread and post-fire smoke exhaust. The development of fires in these complex utility tunnels must be investigated to provide robust, evidence-based guidelines for designing safer energy infrastructure and developing more effective fire protection strategies, thereby enhancing the resilience and safety of urban underground infrastructures. This study aims to quantify the impact of tunnel slope on fire spread behavior and to evaluate how daily operational ventilation strategies affect both sloped and long-ventilation-compartment tunnels.MethodsThis study employs the numerical simulation software Fire Dynamics Simulator using an actual utility tunnel project as the engineering basis to investigate the development patterns of cable fires in utility tunnels under varying longitudinal slopes (0%, 1%, 3%, 5%, and 10%), ventilation compartment lengths (200, 400, and 600 m), and daily air exchange rates (2, 4, and 6 h−1).ResultsThe findings show that for utility tunnels with longitudinal slopes, the natural airflow generated by the stack effect of a cable fire interferes with combustion, flame spread, and smoke propagation, resulting in accelerated fire spread on the right side of the tunnel. At a 10% slope, the maximum flame spread rate on the right side is 0.183 m/s, a 22% increase over the zero-slope conditions. Increasing the daily air exchange rate has a greater effect on suppressing fire spread in areas with large slopes. At an air exchange rate of 6 h−1, the right-side spread range of a cable fire reduced by 9 m under a 10% slope, while it reduced only by 7 m under a 3% slope. For utility tunnels with long ventilation compartments, extending the compartment length increases the airflow travel distance, reducing airflow pressure along the tunnel and weakening the influence of the airflow on fire development. Increasing the air exchange rate has a limited impact on the development of cable fires in long ventilation compartments of utility tunnels. Compared to no-ventilation conditions, air exchange rates of 2, 4, and 6 h−1 suppress fire spread only by 0.55%, 0.55%, and 1.67%, respectively.ConclusionsThe aforementioned results indicate that increased air exchange rates can effectively constrain fire spread in steeply sloped tunnels by counteracting the stack effect. However, their impact is markedly diminished in long ventilation compartments due to airflow attenuation over distance. The research results provide data and technical support for fire safety design and protection requirements in actual underground utility tunnels. The quantitative data and mechanistic explanations presented in this study can inform the development of enhanced safety standards and operational protocols, ultimately mitigating the risks associated with cable fires in the increasingly complex underground lifelines of modern cities.}
}