Enhancing Fire Safety in Urban Bifurcated Tunnels: An Investigation of Slope and Curvature Effects on Fire Dynamics and Smoke Temperature Distribution

This study delves into the critical aspects of fire safety in urban bifurcated tunnels, focusing on the influence of slope and curvature on fire dynamics and smoke temperature distribution. Through a combination of model-scale experiments and numerical simulations, the research investigates how these structural features affect flame morphology, high-temperature smoke location, maximum smoke temperature, and longitudinal temperature attenuation. The findings reveal that tunnel slope significantly impacts smoke flow and temperature distribution, with increased slope accelerating downstream smoke movement due to the stack effect. Conversely, variations in tunnel curvature have a subtler impact, with the maximum smoke temperature shift observed across varying curvature radii being around 20 K. The study establishes a clear link between the structural features of bifurcated tunnels and the fire thermal environment, highlighting the critical role of slope in resilient tunnel systems. Mathematical predictive models for maximum smoke temperature rise and longitudinal temperature attenuation were developed and validated, offering valuable applications in infrastructure planning and emergency management. The relative errors were within 20% when comparing the predicted values with previous full-scale experimental data, demonstrating the models' accuracy and reliability. This research addresses a critical gap in the literature by systematically examining the specific impacts of structural features on fire dynamics, providing essential tools for assessing risks and optimising evacuation procedures during tunnel fire incidents.