Effect of freezing and thawing on the physical properties of red sandstone
The experiment was conducted on the red sandstone samples obtained from the same piece of large rock from Shaanxi to test data comparability. The raw sample was sent to a test chamber to undergo sleeve hole coring, cutting, polishing, and other processes, and finally international standard sample of Φ 50 × 100 mm was obtained. After vacuum pump-forced saturation of the sample, rock quality, dimension, and longitudinal wave velocity were recorded. According to the longitudinal wave velocity measured, all the samples were divided into six groups of freeze-thaw cycles: 0, 5, 10, 20, 40, and freeze-thaw damage. Damage group is mainly used for measuring samples’ longitudinal wave velocity under freeze-thaw cycles. All samples were sorted into the fast freeze-thaw test machine with temperature cycle of −20 to + 20°C and +20 to −20°C. The freezing and thawing damage and failure behavior of the rock were observed
As a common natural material prone to damage, rock generates a large number of pores and microcracks, with high moisture even after a long time of geological processes. From the study of the freeze-thaw damage failure mechanism of rock, we find that the internal stress of rock changes with the high-low temperature and new cracks emerge. The local cracks grow into overall cracks gradually, thereby damaging the structure of rock. From the aspect of macroscopy, the rock strength decreases with the increase of deformation, rock cracking, and peeling[1-5]. These phenomena have certain influence on the construction, operation safety, and reliability of rock engineering in cold region. The analysis of physical properties of rock under freeze-thaw condition has a great practical significance for the engineering constructions in cold region.