Study on the simulation method and mesoscopic characteristics of rock freeze-thaw damage

The damage to saturated rock caused by freeze–thaw cycles seriously affects the stability of projects in cold regions. To accurately obtain the mechanical characteristics of rock after freeze–thaw damage, this paper extracts the microscopic pore structure parameters of freeze–thaw sandstone based on CT scanning tests. Functional relationships between the number of freeze–thaw cycles and both the frost heaving coefficient and thawing coefficient of pore particles are established, and a new method to simulate the mechanical behavior of freezing-thawing rock is proposed based on PFC3D. The CT test results show that the freeze–thaw cycle causes a certain degree of damage to the mesopore structure of sandstone. The sensitivity of each pore structure parameter to characterize the damage is pore volume > effective porosity > porosity > pore radius > fractal dimension > throat length > throat radius > coordination number. Numerical simulation results show that with the increase in the number of freeze–thaw cycles, the internal damage degree of sandstone is more obvious, and the bearing capacity declines. In addition, the rock mainly produces tensile cracks during the freeze–thaw cycle, and failure occurs first outside the rock. The research results reveal the freeze–thaw damage mechanism of rock more accurately.