Study on the Thermophysical Properties of Clay Under Repeated Freezing and Thawing

The thermophysical properties of soil are crucial factors for understanding the heat distribution in soil layers, especially in cold regions. Therefore, to analyze the effect of freezing and thawing action on soil thermophysical properties, here, samples with varying water content were subjected to different numbers of freezing and thawing cycles from 0 to 11 in a laboratory setting, and the thermal conductivity, thermal diffusion coefficient and volume heat capacity were measured and analyzed. Five previously proposed thermal conductivity models were evaluated, and a novel thermal conductivity model was developed based on the concept of the tortuosity and parallel model. The results showed that the thermal conductivity and volume heat capacity vary in direct proportion with the number of freezing and thawing cycles up to seven cycles. Beyond seven cycles, with repeated freezing and thawing action, samples with varying water content reach a residual porosity ratio of 0.5142–0.5345. Both the water content and freezing and thawing action influence the soil thermophysical properties, with water content playing a more important role than freeze–thaw cycles. Among these five models, the Kersten model was found to be the best, followed by the Johansen model, Lu et al. model, parallel model, and serial model. respectively. The Cote and Konrad model demonstrated the poorest performance. In addition, the tortuosity–parallel model was able to efficiently calculate the thermal conductivity of clay under freezing and thawing action.