Abstract: Seven full-size straddle monorail tunnel models with different cross-section shapes were established through numerical simulation. It was found that the ceiling temperature in the rectangular tunnels was generally higher, followed by tunnels with vaults, and the ceiling temperature in square tunnels was generally lower. The temperature at the bottom of the circular tunnel was the lowest among all the tunnels. Under the condition of large fire power, the slope had little effect on the critical wind speed. However, the effect of slope on the critical wind speed was more obvious far from the fire source: with the increase of slope, the control wind speed in the uphill direction decreased significantly, while it increased slowly in the downhill direction.

Key words: tunnel fire; cross-section shape; slope; smoke distribution; critical wind speed