FIRE RESISTANCE OF CAST IRON TUNNEL LINING WITHOUT FIREPROOF COVERING

Nowadays subway is one of the important parts of transport system in large cities. It is necessary a lot of time and money to keep up the efficiency of subways work and ensuring its fire protection. The collapse of the supporting structures of the subway tunnels due to fire complicates the firefighting and for long disrupts the normal functioning of subway. Lining of deep foundation subway tunnels working in hard usage are made of cast iron liners (tubing). The existing methods for calculating the limit of fire-resistance of steel structures do not take into account the features of cast iron tubing usage, such as difference properties of cast iron and iron and heat transfer from the unheated surface in the surrounding soil. The present article is brought the calculating of heating process of the cast iron tubing with account of heat release from the unheated surface in the surrounding soil. It was shown the influence of thermo-physical soil properties on the process heating of cast iron structures.