Comparative Evaluation Of Conventional And Resin Bolting Systems

Over the past few years, the use of fully grouted bolts to support the roof of underground openings has increased dramatically. While conventionally anchored bolts effectively reinforce the strata of over 80 percent of mine workings, the use of resin grouted bolts in areas of severe roof conditions has resulted in a substantial reduction in roof falls and an overall improvement in both safety and production. The Roof Control Group of Pittsburgh Technical Support Center, Mining Enforcement and Safety Administration, has conducted numerous field and laboratory investigations to isolate parameters which contribute to the effectiveness of both conventional and resin bolting systems. Specially developed strain-gamed resin bolts, compression pads and differential sag stations installed during the mining cycle have generated data reflecting the loading characteristics and resulting roof stability associated with each type of support. Additional investigations have produced optimum installation parameters of the two systems including the effectiveness of thrust/torque controls for conventional bolts and various bolt/ hole diameter combinations for fully grouted rods. Theoretical analyses, coupled with the actual field and laboratory findings and numerous installation observations have facilitated basic comparisons of the working mechanisms and failure modes of both resin and conventional systems.