Numerical investigation on flexural performance of retrofitted tunnel lining with short bolts and steel-plate

To establish the flexural performance of a retrofitted anchor-bolted steel plate reinforced structure as a cast-in-place tunnel lining, we conducted a numerical analysis using bend-compression tests. The current rehabilitation structure involves the combination of a long bolt and an H-shaped steel girder. However, installing the long bolt is complex and can damage the waterproof structure. Furthermore, the H-shaped steel girder can intrude into the tunnel clearance. To overcome these limitations, we replaced the existing long bolts and H-shaped steel girder structure with girders using short bolts. The developed numerical model was validated against the experiment model based on the failure pattern, load-deflection, and load-strain results. Three initialised cracks of different depths were considered and produced on the beams. The numerical results unveiled the flexural-tensile failure pattern and demonstrated significant enhancements in flexural capacity, stiffness, and ductility. The proposed short anchor-bolted steel plate system is a viable option for repairing cast-in-place tunnel linings.