Effects of freeze-thaw cycles on granite failure using acoustic emission test

Rock subjected to freeze-thaw (F-T) cycles may experience alterations in structural integrity and potentially impact its strength. This study investigates the effects of F-T cycles on granite by analyzing the acoustic emission (AE) signals recorded during uniaxial compression tests, characterizing the damage responses of the granite influenced by repeated F-T cycles. The results indicate significant reductions in uniaxial compression strength (UCS) and P-wave velocity as the number of F-T cycles increases. AE analysis reveals progressive damage accumulation, characterized by distinct stages of microcrack development. A parameter, AE energy intensity, is introduced to describe the failure process, showing that the typical AE quiet period in the failure stage is absent in granite pretreated with F-T cycles. Using the superlet transform method, AE frequency and amplitude are analyzed, revealing amplitude evolutions across three frequency domains. The results show that decreasing portions of signals in the high-frequency domain for granite are influenced by F-T cycles. These findings enhance understanding of rock degradation under F-T cycles, offering valuable implications for rock engineering in cold regions.