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 ex-tracts 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.