Uniaxial compressive strength of Shikotsu welded tuff and Bibai sandstone at sub-zero temperature

Abstract

Understanding strength and deformation of frozen rock is important for stability assessment of a rock slope in cold weather regions because surfaces of the rock slope often get frozen in winter. In this study, strength and deformation of frozen rock specimens of Shikotsu welded tuff and Bibai sandstone were investigated by uniaxial compression test at -20oC (253 K). Failure processes of both rocks were also considered based on their deformation behaviors. Larger deformation of wet specimens was found than that of dry ones in both rocks due to pore ices plastic deformation. However, it was found that the effect of water content on strength depends on rock type. UCS of wet specimens of Shikotsu welded tuff was greater than that of dry ones. In contrast, UCS of wet specimens was smaller on Bibai sandstone. The former phenomenon can be interpreted by inclusion effect of presence of pore ice. The latter phenomenon can be explained due to stress corrosion by unfrozen water or reduction in friction coefficient of crack surfaces by pore ice.