Abstract: The phase change evolution of pore water was analyzed in the freezing process. Based on the mechanism of sensible heat and latent heat, the frozen soil was divided into freezing soil and stable frozen soil. According to the physical meaning of latent heat, the specific heat of soil should be stepwisely calculated, namely melting stage, freezing state and frozen state as the temperature gradually drops from a general temperature to a larger negative temperature. In the melting stage, the pore water is always in the liquid phase. In the freezing stage, existing liquid water can be frozen into ice. In the frozen state, there exists no liquid water can be frozen into ice. Thus, the cooling of freezing soil would be accompanied by releasing of sensible heat and latent heat. In frozen soil, the further cooling was accompanied by releasing of sensible heat. Then, based on the weighted superposition of specific heat capacity of mixture, the specific heat of the frozen soil is investigated. A method is developed for calculating the specific heat capacity of frozen soil with consideration of latent heat.

Key words: frozen soil, specific heat, latent heat, freezing soil, stable frozen soil, weighted superposition