Practical Investigations into Resin Anchored Roof Bolting Parameters

Resin bolt parameters, such as back pressure and gloving, and their effect on ground support system performance, remains one of the fundamental areas of rockbolt research. The majority of previous studies into resin bolting parameters have utilised various methodologies to investigate the effect of a singular parameter. Unfortunately, due to the variability in methodologies and the relatively narrow field of study of each research project, a holistic conclusion into the exact science behind various results is unable to be drawn. It is the focus of this research project to conduct a detailed and consistent testing program, which attempts to simulate real world conditions as closely as possible, in order to provide the industry with engineered roof bolting solutions to specific underground roof properties. Recently published studies have implemented steel piping as a simulated borehole and have reported relatively high back-pressure measurements. As part of this project, testing conducted both underground and in a cement block, have recorded back-pressures in the range of 4-10 MPa, which are substantially lower than previous tests conducted in steel piping. Rockbolts installed in an underground coal mine using a continuous miner have been over-cored, the core has been cut into 100 mm lengths and each sample has been push tested. After push testing, the samples from the top 300 mm of each bolt were inspected for gloving. Almost all of the recovered rockbolts experienced some degree of gloving within the top 300 mm of its length. The average severity of gloving within these specimens was found to be relatively minor. It was found that gloving can reduce load transfer by 4-6 kN per 10% of gloved surface area.