Numerical simulation study on the ceiling maximum temperature distribution characteristics of herringbone slope tunnel fire

This study investigates the ceiling maximum temperature distribution under various slope configurations when a fire source is located at the transition point of a Herringbone slope tunnel, with fire heat release rates of 10 MW, 20 MW and 30 MW. Results show that in the quasi-steady state, when the slope on the low-gradient side is 1%, the natural induced airflow velocity and fire environment are significantly influenced by the slope configurations on both sides of the transition point. Furthermore, the induced airflow velocity is directly proportional to the 0.1136th power of Q*H*. When the slope on the low-gradient side exceeds 3 %, the natural induced airflow velocity and fire environment are less affected by the slope composition on both sides. These findings provide a basis for optimizing ventilation and smoke exhaust design in Herringbone gradient tunnels.