Angle Shear Testing of 15.2 mm Seven Wire Cable Bolt
Rock Mechanics and Rock Engineering
This paper focuses on the experimental study of shear testing of 15.2 mm, 25 t capacity seven wire cables at zero, 30° and 45° angles using two different shear testing facilities at the University of Wollongong (UOW) and the University of Southern Queensland (USQ) in Toowoomba. A circular double-shear rig MK-IV was used for testing cable perpendicular to the sheared joint faces (zero angle of orientation), while testing the cable at 30° and 45° was carried out using a larger-size rectangular-shaped rig. Testing was carried out based on the double-shear testing methodology wherein cable bolts were fully encapsulated using Stratabinder HS inside of three concrete blocks representing host rocks. This study was part of the tri-universities-funded ACARP project C27040 awarded jointly to the University of New South Wales, University of Wollongong and University of Southern Queensland. The objective of the experimental testing programme was to provide the essential information for the development of numerical models that included not only the technical parameters, but also the behavioural outcomes from various tests with respect to the angles of testing and their effect on the nature of cable failure, be it pure shear, tensile shear or shear tensile, cable pretension and the credibility of the effectiveness of the Barrel and Wedge (B&W) anchorage system were evaluated. Laboratory facilities at both UOW and USQ were used in the study. The prepared double-shear samples were then positioned inside of compression testing machines and were subjected to shear testing. The values of shear load and displacement were recorded for various inclinations angles. It was found that increased angle of shear contributes to increased stiffness of the cable in shear with other parameters being equal. Subroutine codes were developed in UDEC and 3DEC to simulate shear behaviour of cable bolts installed in angles for different pretension loads. The numerical simulations indicated that UDEC and 3DEC can simulate the general shear behaviour of cable bolts reasonably well for various inclination angles and pretension values.
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Australian Coal Industry’s Research Program