Authors: Yan-feng Li , Jun-mei Li and Yu-sheng Hou
Theoretical analysis and numerical simulation have been carried out to investigate the critical velocity in a tunnel cross-passage. Considering the effect of train blockage, several cases are studied by FDS software to determine whether the critical velocity can control smoke in the cross-passage or not. Result indicates that the distance of the train head away from the cross-passage is related to the 1/2 power of tunnel velocity. During the train cross the cross-passage, the value velocity of the cross door increase gradually and then decrease when the middle of the train is situated at the door of cross-passage. The maximum value of velocity is greater than the critical velocity calculate by Froude model. In other cases, the air velocity fails to prevent smoke propagation from accident side of the tunnel and the gas full of the cross-passage cause risk of evacuation.
Keywords: tunnel cross passage; critical velocity; train; blocking;, smoke movement