Macro-mesoscopic Correlation Investigation on Damage Evolution of Sandstone Subjected to Freeze-Thaw Cycles

Freeze-thaw action is one of the primary factors causing rock damage in seasonally frozen regions. Investigating macroscopic and mesoscopic correlations is essential for examining the damage evolution of rocks subjected to freeze-thaw cycles. As a typical type of rock, sandstone was herein selected to examine the influence of freeze-thaw cycles on its mesoscopic structure and macroscopic mechanical properties. The computed tomography (CT) scanning images indicate that the structural integrity of sandstone is undermined disrupted at the mesoscopic level during freeze-thaw cycles, leading to changes in equivalent radius of the pores, of which the mesopores (i.e., pores with equivalent radii ranging from 100 to 500 mu m) are most significantly affected. The results from uniaxial compression tests demonstrate that both the compressive strength and elastic modulus decrease exponentially with the number of freeze-thaw cycles. After 135 freeze-thaw cycles, the degradation rates of compressive strength and elastic modulus are 59.18% and 63.87%, respectively. Based on the macro-mesoscopic results, the macroscopic and mesoscopic damage variables were modified, whereby the freeze-thaw damage evolution functions were proposed. The damage evolution in sandstone subjected to freeze-thaw cycles is characterized by correlating the macroscopic mechanical response with the mesoscopic damage variable, thus deepening the knowledge of rock freeze-thaw damage mechanisms. Damage evolution in sandstone subjected to freeze-thaw cycles was investigated by macro-mesoscopic correlation.Equivalent radii of pores in sandstone during freeze-thaw cycles were examined.Mesoscopic damage variable was modified to quantify the freeze-thaw damage in sandstone.Damage evolution functions were developed based on modified damage variables.