Numerical Investigation of the Temperature Field of Freeze-proof Separate

To analyze the temperature field of freeze-proof separate lining in cold-region tunnels, based on a tunnel on national highway number 307, the numerical model was established by the finite element software ANSYS, combined with the heat transfer theory using a cylindrical coordinate system. The change law of temperature field of the separate lining was investigated when the ventilation temperatures were -5℃, -10℃ and -15℃. The heat insulation effect of separate lining was also analyzed when the diameters of holes in the insulating layer were 5 mm, 10 mm and 15 mm, respectively. The results show that the temperature of lining and rock masses decreases gradually with the decrease of ventilation temperature and that the maximum temperature difference occurs in a closed air layer; considering that the temperature is still above 0℃. When the ventilation temperature is -15℃, the separate lining structure can protect the tunnel from freezing damage. The temperature field of the lining changes significantly if the diameters of holes in the insulating layer are large; the temperature of rock masses is -8.5℃ when the diameter is 15 mm, and the structure of the tunnel may suffer freezing damage. The tightness of the insulation layer has significant influence on the heat insulation effect of separate lining.