Static and dynamic mechanical properties and deterioration of bedding sandstone subjected to freeze-thaw cycles: considering bedding structure effect.

The bedding rock widely exists in nature and its mechanical properties are complex. In this study, the Φ100 mm split Hopkinson pressure bar (SHPB), freeze-thaw(F-T) cycle test system joint with scanning electron microscope and other facilities are applied to investigate the static characteristics, impact characteristics, and damage microstructure of the bedding rock under freezing and thawing conditions. Our experimental results show that under the F-T cycle conditions, the peak point deteriorating path of the static stress-strain curve and the post-peak strain softening curve of the vertical and parallel bedding sandstone specimens have obvious anisotropic characteristics. Parallel bedding specimens have a "pressure bar" effect when loaded. Under the dynamic mechanical test, the peak stress of the vertical bedding specimen is always larger than that of the parallel bedding specimen, and the difference between the two becomes larger while the impact velocity increases. Finally, our microscopic analysis indicates that the main reason for the formation of fissures in the bedding sandstone under the F-T cycle is the cracking of the cement and the shedding of the mineral particles, while the fracture of the mineral particles rarely occurs. The results can provide theoretical guidance for geotechnical engineering in alpine regions.