Study of the Bond–slip performance of grouted rockbolt structures under the coupling effects of temperature and corrosion

Due to the “three high and one disturbance” effect, the high-temperature and humid environment in deep tunnels leads to the corrosion of rockbolts, decreases the stability of support structures, and endangers tunnel safety. Therefore, the stability of grouted rockbolt structures in high-temperature and humid environments must be addressed. In this work, rockbolts were corroded for different time periods and at different temperatures to study the bond–slip performance of corroded grouted rockbolt structures. Based on the load evolution process and failure mechanism of the grouted rockbolt interface, a bond–slip model considering temperature and corrosion was constructed. The results indicate that the coupling effect of temperature and corrosion exacerbates the deterioration of bond performance of the bond interface; as the temperature increases, the ultimate load of the corroded grouted rockbolt structure first increases but then decreases. When the temperature was 35 °C, the maximum limit load was reached. The bond strength and peak slip length of rockbolts significantly decrease under high corrosion rates. The rust expansion effect of rockbolts increases the radial pressure at the grouted rockbolt interface, leading to changes in the failure mode of rockbolts. The proposed bond–slip model, which considers the temperature and corrosion rate, can accurately reflect the actual load transfer behavior of rockbolts in complex environments.