Deformation and Failure Characteristics of Uniaxial Compression Prestressed Red Sandstone Under Short-Term Immersion Conditions

Abstract

To study the impact of short-term water immersion on rock structures during water inrush or storage, a series of water immersion uniaxial compression (UC) tests were conducted on prestressed red sandstone. The effects of prestress levels (0, 0.5σ_c0, 0.7σ_c0, and 0.8σ_c0; σ_c0 is the uniaxial compressive strength) and immersion heights (0, 1/8H, 1/4H, 1/2H, and H; H is the specimen height) on the deformation, strength, and failure characteristics of red sandstone were analyzed. Furthermore, recommendations for treating underground rock structures affected by short-term water immersion were proposed. The results indicate that: during the prestress immersion stage, the deformation of the specimen with 0.5σ_c0 tends to stabilize; the specimen with 0.7σ_c0 maintains slow deformation and no failure; and immersion can cause failure to the specimen with 0.8σ_c0. The strength of red sandstone first increases and then decreases with the increase of prestress, reaching its maximum at 0.5σ_c0. The strength of red sandstone decreases with the increase of immersion height. Partially immersed specimens demonstrate nonuniform failure characteristics, with cracks and surface spalling preferentially occurring in wetted regions. Moreover, as immersion height increases, the spalling area before specimen failure expands. An optimal prestress range exists for red sandstone under short-term immersion, within which the weakening effect of water on strength is minimized.