Shear performance degradation of bolted rock joint under corrosion-temperature coupling

In complex in-situ service environments, anchorage systems are often exposed to groundwater containing acidic or alkaline components and subjected to varying temperatures. A series of direct shear tests were conducted under acidic, neutral, and alkaline conditions at three different temperatures, aiming to investigate the influence mechanisms of this coupling effect on the shear mechanical behavior of bolted joints. The study systematically analyzed the shear performance of threaded rock bolts embedded in jointed rock masses under these combined conditions. The results show that in acidic environments, the high activity of H⁺ ions rapidly disrupts the passive film on the bolt surface and accelerates anodic Fe dissolution, resulting in a decline in anchorage performance with increasing temperature and a pronounced brittle failure in the shear response. In neutral environments, the bolts experience mild uniform corrosion and localized pitting, with shear performance falling between that observed in acidic and alkaline conditions and decreasing gradually with temperature. In contrast, the abundance of OH⁻ ions in alkaline environments promotes maintain passive film stability, leading to minimal corrosion, stable shear performance, and ductile failure characteristics. Observations of shear fracture traces on joint surfaces and the morphology of corroded bolts further confirm the progressive transformation of shear failure modes under the combined effects of corrosion and temperature. Microscopic analyses reveal that steel undergoes the most severe corrosion in acidic conditions, develops a thick and porous rust layer in neutral environments, while the formation of a passive film in alkaline media markedly mitigates corrosion. • Corrosion–temperature coupling influences the shear behavior of bolted rock joints. • Acidic environments accelerate corrosion and reduce shear strength. • Neutral causes pitting, while alkaline conditions help preserve bonding and capacity. • SEM–EDS confirms corrosion features consistent with shear response.