Barrett, Jye (2024) Shear Behaviour of Sandy Clay Infilled Rock Joints. [USQ Project]
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Abstract
Understanding the shear behaviour of rock joints is critical to improving the stability and safety of engineering structures, encompassing everything from tunnels to bridges and foundations. Whilst significant research has been conducted previously, further research is required to fully
understand and model the shear capacity of rock joints under varying conditions including loadings and infill material properties. In many situations, a significant factor of safety is applied to structures to counteract the unknowns associated with rock joints. Further research and a greater understanding of rock joint shear capacities will allow this factor of safety to be reduced resulting in more economical and sustainable designs.
This project uses direct shear testing machines to investigate the shear behaviour of sandy clay infilled rock joints for a range of normal stress values. Rock samples were created by pouring cement grout into 3D-printed moulds with a triangular asperity. Shear testing was conducted using the ShearTrac2 shear testing machine with varying infill material thicknesses and applied normal stresses. The study tested one infill material type with four thicknesses (0 mm, 1 mm, 2 mm and 3 mm) and 4 loading conditions (150 kPa, 300 kPa, 450 kPa and 600 kPa).
The bulk data was processed using Excel to produce graphical representations of the shear and normal stress against the shear displacement of the joint. The main observation from this project was that the introduction of infill material into the rock joint greatly reduced the maximum shear capacity of the joint. The increase in infill material thickness had little effect on the shear stress of joints with lower applied normal stresses, as the applied normal stress increased the infill material thickness had a greater impact on the shear strength of the rock joint. Overall, the inclusion of material within a rock joint reduces the interaction between the asperities of the joint resulting in lower shear stress values.
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| Item Type: | USQ Project |
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| Item Status: | Live Archive |
| Faculty/School / Institute/Centre: | Current – Faculty of Health, Engineering and Sciences - School of Engineering (1 Jan 2022 -) |
| Supervisors: | Mirzaghorbanali, Ali |
| Qualification: | Bachelor of Engineering (Honours) |
| Date Deposited: | 06 Oct 2025 23:18 |
| Last Modified: | 06 Oct 2025 23:18 |
| Uncontrolled Keywords: | rock joints; sandy clay; shear testing |
| URI: | https://sear.unisq.edu.au/id/eprint/53017 |
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