Experimental and numerical investigation on the deterioration mechanism for grouted rock bolts subjected to freeze-thaw cycles

Development of durable anchorage systems for slope support in high-cold and high-altitude areas has been becoming a global research hotspot. This paper is addressed to the deterioration mechanism of bond and anchorage performance of grouted rock bolts under the action of freeze-thaw cycles. A laboratory-based physical simulation was employed to study the anchoring force, displacement, anchor stress, and bond strength between bolts and cement mortar. It was shown that the anchoring force decreased by 27% after 30 freeze-thaw cycles by means of the pull-out tests and microstructural characterization. It was found that the maximum anchor stress existed in the middle part of the anchorage, where the shearing failure was most likely to happen. Using bond-slip curves, four stages of bolt slippage were established. The analysis on the bolt deformation indicated that shearing failure was caused by a decrease of strength and stiffness of the cement mortar, which led to a loss of bonding ability. A degradation model for anchoring limit was established and the reliability of this model was ascertained. This may serve as a reference for future application of grouted rock bolts designed to be used in low-temperature conditions.

Automated summary

Development of durable anchorage systems for slope support in high-cold and high-altitude areas is a global research hotspot. This study investigated the deterioration mechanism of bond and anchorage performance of grouted rock bolts under freeze-thaw cycles. The results showed a decrease in anchoring force after 30 freeze-thaw cycles, with the highest anchor stress in the middle part of the anchorage, likely leading to shearing failure.