Theoretical and numerical study on ceiling temperature distribution of fire in the SRRT with curvature considering train blocking

The slopping rack railway tunnel (SRRT) with curvature is applied to pass through mountainous areas due to the terrain. And the temperature distribution under train blocking in the SRRT with curvature is significantly different when a fire occurs, posing a great threat to personnel safety. The train blocking and two curvature types of C-shaped and S-shaped are considered, and the mathematical expressions for temperature distribution with coefficients of slope and curvature are derived. The effects of slope, curvature, and train blocking on ceiling temperature are investigated using numerical simulation, and the applicability of the mathematical expressions is demonstrated through fitting. The results show that the mathematical expression for ceiling temperature distribution is a piecewise function with a stepped-down descent. The temperature attenuation is separated into three stages for C-shaped, and four stages for S-shaped. The coefficients are approximately linear with slope and curvature radius respectively. The train blocking on the ceiling maximum temperature for C-shaped is of a stronger effect than for S-shaped, and the slope on the temperature at the train tail for C-shaped is of a weaker effect than for S-shaped.