Long-term mechanical performance analysis of post-grouting prestressed resin bolt under anchorage creep.

• A theoretical model was developed to explain how PRG bolts maintain support force after creep in the anchoring section. • Indoor experiments using Distributed Optical Sensing (DOS) technology revealed the changes in axial force distribution over time for both PR and PGR bolts during service. • The mechanical properties of PR and PGR bolts after long-term loading were evaluated through mechanical testing. As an effective solution for controlling deformation in surrounding rock, prestressed rock bolts have been increasingly adopted in transportation tunnels. However, the potential for prestress loss and anchorage failure due to creep in the anchorage material over extended service life necessitates further investigation. In response, this study investigated the long-term mechanical performance of a prestressed post-grouting resin bolt, focusing on its supporting effect and mechanical behavior after anchorage creep. We began by establishing a model that explained the mechanical mechanism of the grouting segment. This model was then used to analyze the impact of grouting material properties. Additionally, the bearing characteristics of the prestressed post-grouting resin rock bolt during reloading were assessed. Furthermore, a laboratory experiment was conducted using distributed optical fiber strain sensing (DOS) technology to evaluate the long-term behavior and mechanical performance of both prestressed resin anchor bolts (PR bolts) and prestressed post-grouting resin anchor bolts (PGR bolts) under various loading conditions. The results indicated that the PGR bolt significantly reduced prestress loss compared to the PR bolt, with reductions of 13%, 15%, and 16% at pretensions of 50 kN, 80 kN, and 110 kN, respectively. Additionally, PGR bolts can avoid stress concentration on the anchoring interface under long-term loads, reducing the risk of anchoring failure when re loaded. Taken together, the findings of the research indicate that PGR bolts can maintain higher prestress and strength in long-term support, and the theory model helps design the grouting parameters of PGR bolts. [ABSTRACT FROM AUTHOR]