Bolt Profile Geometry Effect on Load-Bearing Characteristics of Fully Grouted Rock Bolts
M. Bagheri1, H. Bakhshandeh Amnieh2, H. Jalalifar3
1University of Kashan, Kashan, Iran
2University of Tehran, Tehran, Iran
3University of Kerman, Kerman, Iran
Keywords: Fully grouted rock bolt, bolt-grout interface, pull-out test, bolt profile, embedment length
Abstract
A series of laboratory pull-out tests were performed on several types of bolts to investigate the effect of profile geometry of resin grouted bolts on load transfer mechanism. Therefore, three different types of bolts were used to prepare twelve series of specimens with different profiles. To evaluate the effect of bond length, the specimens were made using rebar bolts with two embedment lengths of 75 mm and 150 mm. The results showed that load transfer capacity and displacement at peak load were effectively related to the profile configuration and annulus thickness of resin. The bolt types T1 and G2 had higher peak share stress levels and the bolts with a rib spacing of 12.5, 16, 25 and 8 mm had the highest peak shear strength, respectively. By decreasing the rib spacing and embedment length, the system stiffness increased. In the bolt types T1 and G2, by increasing the embedment length from 75 mm to 150 mm, the shear stress decreased by 7.8% and 10.5% and their stiffness decreased by 60.8% and 75.6%, respectively. As the thickness of the resin annulus increased, the peak load decreased.
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