In order to improve the prediction accuracy of frozen soil temperature field and reduce the testing work load of thermal parameter

the inversion formula of unfrozen water content is deduced based on the thermal conductivity and the three-phase composition of soil

water and ice in saturated frozen soil. According to the two-phase structure of dry soil or saturated soil

a formula for predicting thermal conductivity of soil minerals is derived. The specific heat and thermal conductivity of silty clay are measured at different negative temperatures; and the unfrozen water contents of silty clay under different negative temperatures are calculated respectively through the recurrence method for unfrozen water content by specific heat and the inversion formula for unfrozen water content by thermal conductivity established in this paper. The thermal conductivity

specific heat and latent heat of frozen soil at different negative temperatures are determined based on the measured and inversed values of unfrozen water content. The thermal parameters calculated by the unfrozen water content are entered into ABAQUS; and the calculated values of frozen soil temperature field with different thermal parameters are obtained. The calculated values of each temperature field are compared with the measured values of the model test. The results show that the reducing testing work load of thermal parameters is feasible from the viewpoint of the unfrozen water content of frozen soil; and the thermal parameters obtained from the inversion of unfrozen water content based on the Johansen method can better predict the frozen soil temperature field.