Abstract: The application of resin bolts to weak and broken surrounding rocks in tunnels faces numerous challenges, such as difficult operations, poor anchorability, and a lack of long-term reliable monitoring means. To address these issues, a novel technical scheme of prestressed hollow anchor bolts with built-in resin is applied to a weak and broken rock tunnel in southwest China to validate its feasibility. Prestressed hollow force-measuring anchor bolts are utilized for tunnel monitoring, while a bolt supporting scheme is optimized based on the monitoring data of surrounding rock deformation and bolt stress. Finally, the proposed optimization scheme is verified by combining numerical simulation results. Research results indicate the following: (1) The prestressed hollow anchor bolts with built-in resin realize the mechanical and rapid construction of broken and soft rock tunnels. The operation time (including drilling) of these bolts in collapsed sections ranges at 6－10 min, and the construction efficiency of bolts is improved by >33%. (2) The prestressed hollow force-measuring anchor bolts with built-in resin can effectively monitor their mechanical state, and the wavelength value shows a good linear relationship with the anchor bolt pulling force. (3) Field measurements indicate asymmetric tunnel deformation with a maximum displacement of 305 mm and a peak axial force of 149 kN in anchor bolts, both of which are observed on the right side of the tunnel crown. Therefore, the original bolt supporting scheme needs to be reinforced and optimized on the right side. (4) Numerical simulation shows that the maximum axial force and maximum deformation of the surrounding rocks of the optimized solution are reduced to 204 mm and 126 kN, respectively, indicating that the developed bolts can significantly enhance the effectiveness of controlling surrounding rock deformation.

Key words: prestressed hollow anchor bolt with built-in resin, force-measuring anchor bolt with built-in resin, tunnel, broken and weak surrounding rock