Impacts of frost heave susceptibility and temperature-changing conditions on freeze-thaw deterioration of welded tuffs

Damage development in rocks by freeze-thaw cycles, a phenomenon that is typical to cold regions, is known to reduce the strength and durability of structures. In this study, a series of freeze-thaw tests were performed on frost and non-frost heave rocks to examine the impact of frost heave susceptibility and temperature-changing conditions on rock behaviors. The freeze-thaw life and uniaxial compressive strength (UCS) of rocks subjected to freeze-thaw cycles were estimated using a model that was based on fatigue damage mechanisms. Furthermore, we proposed a method for estimating the freeze-thaw life of rocks, using expansive strain as an important factor. The results indicated that the Shikotsu welded tuff (a non-frost heave rock) exhibited higher durability than the Noboribetsu welded tuff (a frost heave rock); this may be because the Shikotsu welded tuff had a larger pore radius and more unsaturated pores. The one-dimensional (1D) cooling-heating conditions induced significantly less damage than the three-dimensional (3D) conditions, owing to the continuous migration of free water into the unfrozen zone. The damage model estimated that for the Noboribetsu welded tuff, the freeze-thaw life in the 1D conditions was approximately eight times longer than that in the 3D conditions. Notably, with respect to the Shikotsu welded tuff, a critical freeze-thaw period induced significant expansion, resulting in damage development in the tuff. The freeze-thaw life of each rock sample was estimated based on the magnitude of the volumetric expansive strain. This study contributes to the rational assessment of the stability and durability of rock structures in cold regions.