Experimental Study of the Effects of Borehole Size, Borehole Roughness, and Installation Pressure on the Pull Load Capacity of Inflatable Rockbolts

Abstract An inflatable rockbolt is a steel tube that has been rolled into an omega shape. During installation, water injected the tube, which expands profile of rockbolt, generating radial force against borehole wall. This reinforces rock mass through friction at bolt–rock interface. study aims to quantify effects size, roughness, and installation pressure on pull load capacity bolt. was achieved series tests under laboratory conditions. The test results showed higher in boreholes were either close initial diameter bolt or fully unfolded bolt, 26.8 mm 38.7 mm, respectively, study. stiffness lowest medium-sized (33 33.5 mm). In small boreholes, shoulders tongue are tightly compressed such outward elastic deformation locked after installation. locking enhances addition, found be percussively drilled than diamond-drilled boreholes. additional angle percussive back-calculated approximately 5.83°. also increase as increases range pressures tested. It observed clamped three zones: two side opposite tongue.