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The ease of use and the design flexibility of cable bolts have made them a popular choice for rock support. Cable bolts can be encapsulated with cementitious grout or resin. There is a need to better understand the impact of resins on the behaviour of cable bolts under varying load and stress regimes over their long service life. This study reports on 18 large-scale resin pull-out tests. The testing apparatus minimised the rotational movement of the cable at the exit point by using a fully grouted anchor tube. Six cable bolts, ranging from 50 to 100 tonnes in capacity, anchored using a fast-curing urea silica resin, were tested under monotonic and cyclic loading. Each cable type was tested twice in monotonic loading, and then the average initial peak load was used to generate a cyclic loading pattern. The study found that the resin product had a relatively low load capacity regardless of the cable type, and that loading type had a minimal impact on the results. The cable diameter had a minor influence on the pull-out results. The resin provided a stiff behaviour and an excellent response to repeated loading. [ABSTRACT FROM AUTHOR]

With the increased use of cable bolts in mining and civil projects worldwide, it is important to understanding the performance of these support structures in different scenarios. The axial load transfer mechanisms of six cable bolts were investigated experimentally in this research study. A large-scale pull-out testing apparatus with a capacity of 1000 kN was designed and manufactured as part of the investigation. A common commercial cementitious grout with a uniaxial compressive strength of 60 MPa was used to encapsulate 300 mm length samples. Passive confinement encapsulated each sample to ensure the concrete's integrity during the testing. The encapsulated cable bolts were then subjected to axial loads using a hydraulic ram, with the axial load and displacement measured using a load cell and LVDTs. Two scenarios were investigated: free rotation and restricted rotation. The results demonstrated that the apparatus effectively recorded the behaviour of the cable during pull-out and identified that the radial stiffness of the samples had a significant impact on the overall load of the system. The results also indicated that rotation had a limited influence on the load behaviour of the samples tested. Highlights: Design and manufacturing of a high-capacity 1000 kN pull-out apparatus for newer cables, Rotation investigation showed less adverse effect than previously reported. It was concluded that a zero-rotation test is not feasible as the rotation of the cable inside the annulus is not uniform, Cable modifications such as surface indentation and bulbing significantly change the failure mode from strain hardening or perfectly plastic to strain softening, Interaction of cable strands with grout ridges inside the grout annulus creates relative movements and oscillations in the post-peak loading zone, and Failure is not uniformly distributed in the grout annulus, with higher damage observed at the cable's exit point and minor damage toward the entry point. [ABSTRACT FROM AUTHOR]

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. Highlights: The historical information that sets the record on the early development and application of cable bolt on ground reinforcement along with the relevant literature review was presented, The results of large-scale experimental study on shear behaviour of cable bolts were presented and discussed, The results of large-scale experimental studies on shear behaviour of cable bolts installed in angles for various pretension values were presented and discussed in detail at a level that has not been investigated in previous geotechnical projects, The capabilities of distinct element code in modelling shear behaviour of cable bolts were studied for different geotechnical conditions by developing original subroutine programs, and Parametric studies were carried out to investigate the effects of relevant parameters on shear behaviour of cable bolts. [ABSTRACT FROM AUTHOR]

A fully grouted cable bolt is normally loaded at rock joints by a combination of the axial and shear forces causing both axial extension and shear deformation of the cable. The proposed analyses presented here attempts to predict the joint shear strength and shear displacement. The analyses are based on the statically indeterminate beam theory and some basic findings and conclusions of other researchers. Parametrical investigation is performed on four influence factors including bolt pretension, joint friction angle, concrete strength and bolt installation angle. Although the true plastic moduli of the cable bolt deflecting section at failure are the essential parameters in this analysis, they are practically impossible to determine. Thus, the average cable moduli obtained from the cable tensile strength tests were used. The proposed analytical model was compared with the experimental results, showing a good agreement. This analytical work aims to develop a simple tool for the practicing geotechnical engineer to effectively evaluate the cable shear behaviour and the influence of fully grouted cable bolts on joint shear resistance. [ABSTRACT FROM AUTHOR]

Abstract Cable shear behavior in reinforcing rock discontinuities involves both the axial shear behaviour along the cable-grout interface and the local lateral shear behaviour of the cable deflecting section. This is a complex condition which is difficult to be solved in a theoretical manner. Pile structural elements in Flac3D were used here to investigate this shear behavior with special attention to the influence of cable anchorage length. The employed numerical cable model was firstly calibrated using the laboratory pullout test and a single shear test on a plain Superstrand cable bolt. Then the calibrated model was used to investigate the anchorage length effect on the cable lateral shear behavior. As expected, numerical results show that two demarcation anchorage lengths existed in cable shear tests. In the case of plain Superstrand cable bolt subjected to lateral shear loading at an angle of 90°, the two demarcation anchorage lengths were approximately 2.09 m and 0.61 m. [ABSTRACT FROM AUTHOR]

Pretension is the pre-added axial tensile force on fully grouted bolt systems, which include rock bolts and cable bolts. Although a series of studies via lab testing and analytical modelling proved the importance of pretension in cable bolts, there is no systematic analysis to guide the optimal pretension values to be applied on cable bolts in different engineering geological conditions. Complicated geological conditions, such as anisotropic in-situ stress, bedding plane detachment and country rock deformation, cannot be fully represented in the lab or analytical work. In addition, field scale numerical models to investigate cable bolt performance and its interaction with various geological conditions are rare. This paper analyses the effect of pretension on the performance of cable bolts in underground coal mines via field scale numerical models, with considering different geological conditions (in-situ stress, bedding plane stiffness and rock mass properties). Numerical models were developed based on a case study mine in Australia with challenging ground conditions. The in-situ stress, properties of claystone and bedding planes are considered critical variables to be analysed. The results show higher pretension contributes to higher force along the cable bolt. Neutral points, where shear force in grout materials is zero, are used to describe the pretension-induced stress redistribution on cable bolts. Pretension also has a positive effect on roof and bedding plane management, resulting in a more stable roof condition. In addition, high pretension and high in-situ stress are more likely to result in cable-grout (CG) interface failure since the relative vertical displacement difference between cable bolts and the surrounding rock mass is higher. Once CG interface failure is generated, the pretension effect turns out to be negative, leading to severe roof sagging and bedding plane aperture. This paper provides a guide to the application of pretension in coal mining. • Developed a numerical model to illustrate the effect of pretension on cable bolts. • Analysed effects of pretension and cable-grout (CG) interface failure on cable bolts. • Investigated the relationship between pretension applied and CG interface failure generated along cable bolts. • CG interface failure induced by excessive pretension is more sensitive to bedding plane properties. [ABSTRACT FROM AUTHOR]