This study proposes a new method for calibrating the theoretical model of resistivity versus unfrozenwater content in frozen soils. The method characterizes correlations between the soil mass resistivityand unfrozen water content in the frozen state by investigating the relation between resistivity andliquid water content in the drying state. The essential similarity between the soil mass freezing anddrying processes is analyzed through the process and path of unfrozen (liquid) water reduction. Theresistivity and unfrozen water (liquid water) content were correlated in soil samples with differentparticle sizes (clay, silt, and sandy soil) during freezing and drying. The test results showed that duringfreezing to temperatures below 5 °C (clay), 4 °C (silt), and 3 °C (sandy soil), the unfrozen watercontent thresholds of providing directional migration channels for conducting particles were 17%,14%, and 13%, respectively. During drying, the threshold water contents of clay, silt, and sandy soilwere 15.35%, 14.87%, and 14.34%, respectively. The correlation between the soil resistivity (ρD) andunfrozen water content (θu) in the freezing process can be expressed based on that between the soilresistivity and liquid water content in the drying state. Thus, the theoretical model of unfrozen watercontent can be calibrated by conducting a resistivity test under the drying condition. This new methodis suitable for model calibrations of electrical resistance tomography for engineering applications incold regions..
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