Abstract: The frost heaving pressure generated by water–ice phase change and volume expansion of saturated fractured rock mass in cold regions promote the initiation and expansion of new fractures, and lead to further damage and deterioration of fractured rock mass. To reveal the frost heaving pressure degradation mechanism of fractured rock mass subjected to multiple freeze–thaw cycles, the repeated frost heaving pressure monitoring test was carried out on saturated fractured granite with different macroscopic fractures under different freezing temperatures. The evolution characteristics of cyclic frost heaving pressure and the effect of crack size, freezing temperature and the number of freeze–thaw cycle on the frost heaving pressure of saturated fractured granite were analyzed. The results show that the evolution characteristics of frost heaving pressure in single freeze–thaw cycle is similar, which can be roughly divided into five stages. As the number of freeze–thaw cycles increases, the peak frost heaving pressure decreases exponentially, and the amplitude of peak frost heaving pressure drop increases. The peak frost heaving pressure increases linearly with the increase of crack length. The smaller the crack width, the earlier the frost heaving pressure appears in the freezing and thawing stages. The lower the freezing temperature, the earlier the frost heaving pressure appears. The peak frost heaving pressure increases linearly with the decrease of temperature, and the effect of freezing temperature on the frost heaving pressure weakens with the increase of freeze-thaw cycles. As the freezing temperature decreases, the effect of crack size on the peak frost heaving pressure becomes more significant. The research results can provide reference for the theoretical calculation and numerical analysis on frost heaving pressure of fractured rock masses in cold regions.

Key words: frost heaving pressure, freeze–thaw cycles, fractured rock, evolution characteristics