Predicting the failure of different rocks subjected to freeze-thaw weathering using critical slowing down theory on acoustic emission characteristics

Abstract

Freeze-thaw weathering effectively deteriorates the physical and mechanical properties of rocks and seriously threatens the stability of engineering projects in cold regions. This study investigates the influence of freeze-thaw action on mechanical behaviors and failure prediction of different rocks i.e., sandstone, marble, and granite. The rock samples were subjected to a quasistatic compressive test, and a real-time acoustic emission (AE) monitoring technique was used to reveal the damage characteristics of rocks treated with 0, and 25 freeze-thaw cycles. The autocorrelation coefficient (AC) and variance of the AE count were then calculated by applying the Critical Slowing Down (CSD) theory, and the precursory features of rocks failure under the action of freeze-thaw were examined. The results unveiled that after the freeze-thaw action, the uniaxial compressive strength (UCS) of sandstone, marble, and granite was reduced by 16.5%, 8.36%, and 7.75% respectively. The AE count and the accumulative count correspond effectively to the failure of different rocks under compressive loading. Even though the samples have shown the same variation for AE count and accumulative count but those subjected to freeze-thaw weathering have shown an earlier rise in both AE counts and accumulative counts. It was noted that the AE signals had a CSD phenomenon. The sudden and significant increase in AC and variance curves of AE count, RA, and AF parameters can be used to predict rock failure. Furthermore, the precursory characteristics of different rocks treated with freeze-thaw weathering were compared. The ratios of the early warning to the main fracture and complete failure in terms of time are the highest for sandstone followed by granite, and marble. Moreover, the precursory points of treated samples were earlier than those of untreated samples. It was concluded from the results that AE counts' early warning precursory characteristics are more noticeable than other AE parameters, especially in the variance curves. Hence, the results of this study will provide significant importance to predicting rock failure in cold regions.