A predictive model of unfrozen water content including the influence of pressure

Unfrozen water content has strong control on the permeability, strength and thermal properties of frozen soil. Several techniques have been used to measure unfrozen water content in frozen soil and many models have been developed for its prediction. However, there has been little investigation on the quantitative analysis of the relationship between pressure and unfrozen water content. With the development of artificial ground freezing techniques and deep mining, knowledge of unfrozen water content in frozen soil under high pressure is critical to the stability of the frozen structures. Here, a new predictive model is presented based on the relationship between chemical potential and unfrozen water content and a previous empirical formula. The simulation results are in good agreement with those from laboratory tests. Both the theoretical analysis and the test results indicated that: (a) the pressure applied to frozen soil reduces the freezing point of bulk water and delays the phase change, and (b) unfrozen water content increases with increasing pressure, and at higher pressures the change is greater. The results improve our understanding of the physical and mechanical properties of freezing soil under pressure for artificial ground freezing applications and deep mining engineering.