Abstract: It is known that frost heave pressure goes through the process of initiation, development and dissipation when rock cracks under freeze-thaw cycles. Moreover, both the frost extension of cracking and the degree of frost damage of rock depend on frost heave pressure. Therefore, an analytical model is established for frost heave pressure in an idealized cylindrical closed crack, based on the theory of thermodynamics, seepage mechanics, interfacial mechanics and elastic theory. Besides, the effect of moisture migration on the value of frost heave pressure is investigated. Without considering the moisture migration, the results show that the frost heave pressure increases rapidly with the increase of water saturation in crack and rock elastic modulus Es. Under the condition of and 94%, the frost heave pressure exceeds 15 MPa, which is high enough to drive rocks to initiate cracking. In addition, the rock starts to crack once the water saturation reaches its own critical value, . For rocks with the low permeability below 5×10?14 cm2, a high frost heave pressure can be produced by frozen water in the crack, which easily leads to frost crack propagation. However, for rocks with the permeability above 10?12 cm2, the frost heave water pressure could not cause any damage. The main reason for crack frost propagation in high permeability rock is the disjoining pressure in a microscopic unfrozen water film between ice and rock interface after water frozen.

Key words: fractured rock mass, frost heave pressure, water migration, disjoining pressure, deterioration mechanism