Study On Frostresisting And Antifreezing Strategies Of Extra-Long Highway Tunnel In Cold Area

Taking Zhegushan Tunnel Project as actual background and solving key construction techniques on frostresisting and antifreezing as starting point, this paper applied in-situ test and numerical calculation to study freezing damage mechanics of tunnels in cold area, with the emphasis on analyzing causes of freezing damage of tunnels in cold area.On the basis of investigating and analyzing all kinds of frostresisting and antifreezing measurements applied in the worldwide and aiming at characters of extra-long highway tunnels in cold area, this paper puts forward comprehensive frostresisting and antifreezing measurements favorable for extra-long highway tunnels in China cold area.By means of monitoring and analyzing air temperature, surface temperature of secondary linings, temperature backside secondary linings and temperature of surrounding rock within certain depth, variation laws of temperature of different position inside Zhegushan Tunnel are educed and by computational analysis, the critical temperature of protective heat preservation and insulation layer is determinated as well as protective length of insulation layer.In order to validate applicability of selected insulating material and reliability of thickness of insulating materials, in-situ tests for three different materials are carried out in the exit section of parallel pilot tunnel. Through study and analysis of measured data, insulating properties and in-situ applicability of three different materials are evaluated and instructive suggestions are brought forward for final conduct of insulating layers.