- Title
- Susceptibility of rehabilitated mine batter surface to mass movement
- Creator
- Allen, Tristan
- Date
- 2018
- Type
- Text; Thesis; Masters
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/168528
- Identifier
- vital:13824
- Identifier
- https://library.federation.edu.au/record=b2771670
- Abstract
- The goal of the research is to quantify coal properties that may affect the processes and controls governing rehabilitated brown coal mine surface mass movements. The research investigates weathering of coal and assesses the difference in strength characteristics between fresh and weathered coal. In addition to quantifying the mechanical properties of coal surfaces in a rehabilitated slope, permeability changes due to weathering of coal are also investigated. Changes in coal strength influence sliding resistance. Changes in coal permeability impact pore pressures above the coal surface, which may also affect sliding resistance on the coal – cover interface. To assess these issues, direct and residual shear tests were used to investigate the changes in shear strength due to weathering at low normal stresses applicable to shallow cover materials. Testing was undertaken with abrasive surfaces to simulate sliding on the contact coal surface beneath cover materials assuming that the cover material is stronger than the coal. The roughness of the abrasive surface proved to be unimportant for large strain shear strength. The shear strength for coal with different weathering and normal effective stresses was examined. Coal cohesion was found to be low, but some rebinding of coal would occur with time. A coal residual friction angle of 39.1 and 37.0 degrees was found for the unsaturated and saturated tested coal respectively. Permeability tests using oxygenated water were undertaken to investigate changes to brown coal permeability as a result of weathering. Even with low levels of oxidation achievable with the permeability test apparatus, coal permeability dropped over time. While the magnitude of the reduction was not large for low oxidation magnitudes, the impact on permeability was demonstrated. A weathering index was developed as part of the study to provide a quantitative basis for assessing the weathered state of coal samples. The index employed changes to Fourier Transform Infrared Spectroscopy (FTIR) spectra to define the state of weathering. To assess the rate and magnitude of weathering of coal through oxidation an autoclave was used to artificially weather brown coal. Fourier Transform Infrared Spectroscopy and Gas Chromatography used to analyse the results. As for the permeability testing the autoclave experiments could not be run for sufficient time to progress to complete weathering by oxidation. Nevertheless the principles of the test and the equipment specifications were developed so that they could be used in future to complete the determination of weathering rates. The research has demonstrated the importance of understanding coal weathering at the upper boundary of a rehabilitated coal surface to the potential for cover mass movements due to sliding at the coal cover interface.; Masters by Research
- Publisher
- Federation University Australia
- Rights
- Copyright Tristan Allen
- Rights
- Open Access
- Rights
- This metadata is freely available under a CCO license
- Subject
- Rehabilitated mine; Batter surface; Mass movement; Coal properties
- Full Text
- Thesis Supervisor
- Wilcox, Steve
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