THE ANALYSIS OF THERMAL CONDITIONS IN EXTRA-LONG RAILWAY TUNNELS DURING THE COLD SEASON

The subcool zone length is determined in lining of an extra-long railway tunnel subjected to deep influence of piston effect. The air temperature distribution in the outer air-tunnel lining contact zone is determined as function of the velocity of train and the outdoor temperature in the cold season. The authors review the de-icing methods of tunnel lining: warming-up using a self-tuning heating cable; arrangement of an unheated access gallery and heat insulation. The distribution of the hourly average air temperature in an extra-long railway tunnel is analyzed against of sites of fan heaters. The heat power patterns in the tunnel are estimated by the criterion of the required temperature conditions. It is shown that the most efficient arrangement of fan heaters to maintain the required air temperature in the tunnel is their uniform distribution along the length of the tunnel in combination with installation of warm air curtains at the tunnel faces.