Damage deterioration behavior of granite subjected to freeze-thaw cycles: Experiments and theories

Granite, as an important natural building material, has a significant impact on the stability of engineering structures due to freeze-thaw (F-T) damage. This study aims to reveal the mechanical nature and damage mechanism of F-T damage in granite. The energy evolution law and cracking failure characteristics were investigated based on the unconfined uniaxial compression test, acoustic emission (AE) technique and multiple fractal theory. The early warning methods of granite fracture failure instability were proposed, utilizing the extracted acoustic emission Mel-frequency cepstral coefficients (MFCC). Additionally, the frost damage to pore walls was analyzed based on the thermodynamic principles and the theory of elastic mechanics. The results indicate that the average damage of granite specimen after 200 F-T cycles is 37.76 % and the F-T damage rate is reduced to 0.19 %. Notably, the frozen-thawed granite tends to a more homogeneous fracture mode, and a sudden decrease in the 2nd order coefficient of MFCC prior to rock fracturing could serve as an early warning for instability. The established computational modeling of pore wall mechanics demonstrated that temperature and porosity exert a significant influence on frost damage. This study comprehensively resolved the failure characteristics of frozen-thawed granite, laying a significant theoretical and experimental foundation for understanding the F-T damage mechanism in rock engineering.