Characterizing frost heave pressure distribution on rock crack surfaces during freeze–thaw

Frost heave pressure plays a pivotal role in driving the occurrence and expansion of rock cracks. Thus, understanding the distribution and evolution of frost heave pressure on rock crack surfaces is integral to elucidate the mechanism of rock mass damage caused by freeze-thaw. In this study, a unique frost heave pressure monitoring experiment was performed, employing a membrane pressure sensor to provide real-time monitoring of frost heave pressure distribution across an entire rock crack surface. Simultaneously, temperature changes within the crack during freeze-thaw were monitored. Various factors including freezing temperature, crack water content, and lithology, were analyzed for their influence on the frost heave pressure distribution on the crack surface. Findings indicate that the frost heave pressure evolution during freeze–thaw can be divided into five stages: incubation, eruption, fall, equilibrium, and dissipation. The frost heave pressure is not uniformly distributed across the rock crack surfaces, with 0 MPa pressure on the upper part of the crack. The distribution pattern of frost heave pressure on the crack surface features smaller edges surrounding a larger middle area. No obvious correlation is observed between the maximum frost heave pressure and the freezing temperature. However, as the freezing temperature decreases, the maximum pressure-bearing area on the rock crack surface gradually increases. Additionally, as the water content within the crack decreases, there is a noticeable decrease in the distribution of frost heave pressure on the rock crack surface. Regarding frost heave pressure monitoring tests under four different lithological conditions, crack expansion was observed in fine sandstone, granite, and limestone specimens, but not in coarse sandstone specimens. The findings from this research enrich our understanding of the incubation mechanism of rock mass freeze–thaw disasters in cold regions, and serve as a reference for calculations and numerical simulations of rock crack frost heave pressure in these areas.