Experimental study on transverse fire source and blockage locations influence on tunnel fire temperature distribution

Previous research has commonly assumed that tunnel fire blockage occurs at the central longitudinal axis of tunnels. However, fires may arise at different points within tunnels, each with various distances from the tunnel sidewall. The study aimed to investigate the distribution of ceiling temperature fields across various scenarios of blockage and transverse fire source locations by conducting a sequence of fire experiments within a reduced-scale 1:10 horseshoe-shaped tunnel model. The findings indicate that at sufficiently low ventilation velocities (v’≤0.19), the maximum ceiling temperature rise in the tunnel remains virtually unchanged regardless of the locations of blockage and transverse fire source. For higher ventilation velocities (v’>0.19), the maximum ceiling temperature rise diminishes with greater blockage-fire source distance. Additionally, the maximum ceiling temperature rise increases as the distance between the sidewall and the fire source diminishes. Furthermore, a new model has been formulated to forecast the dimensionless maximum ceiling temperature rise, incorporating both blockage and transverse fire locations.