Abstract: In order to study the effect of freezethaw cycles on the thermal conductivity of tunnel lining, the concrete is simplified to a porous media model, and the thermal conductivity of concrete specimens with different porosities is calculated and analyzed by Hamilton and Crosser theoretical calculation model and simulation software COMSOL. The research results show that: (1) The inverse calculation is carried out on the effective thermal conductivity of the concrete random distribution model, and the effective thermal conductivity of the concrete model with different porosities under different freezethaw cycles is obtained, which helps to determine the nonlinear functional relationship between effective thermal conductivity of the concrete specimens and the freezethaw cycle. (2) The thermal conductivity of lining concrete decreases first and then increases with the increase of freezethaw cycle, and finally becomes stable (increases a little).

Key words: seasonally , frozen tunnel, lining concrete thermal conductivity, porous medium model, porosity, freezethaw cycle