Testing procedure development and preliminary testing of sheath protected rock bolt subject to axial loading

Testing procedure development and preliminary testing of sheath protected rock bolt subject to axial loading

This study investigates the axial load transfer behaviour and elongation characteristics of CT26WR rock bolts encapsulated with MAPEI Stabilcem T grout, using large-scale pull-out testing under controlled laboratory conditions. The project utilised single and double embedment test setups, incorporating strain gauges and extensometers to assess strain distribution, bond strength, and joint elongation. Testing was carried out using a 1000 kN universal testing machine, and post-failure inspections were conducted through precision waterjet cutting. Results demonstrated that grout-sheath debonding and axial cracking within the grout governed failure mechanisms, with no visible bolt or sheath rupture across all configurations. The findings contribute critical knowledge toward understanding deformation behaviour in bolted ground support systems, particularly under high axial loading. The work supports improved design guidelines for elongation-sensitive rock bolts in tunnelling and mining applications and lays the groundwork for future standardisation of elongation testing methodologies.