Underground » Geology
The objective of this project was to develop a new system for evaluating geotechnical boreholes in underground mining. This approach was predicated on the demonstration of a commercial prototype imaging system (the Slim Borehole Scanner (SBS)) which is designed to be suitable for application in all standard geotechnical boreholes and is certified Intrinsically Safe (IS) in Europe.
This ACARP Project (C16019) was designed to test this new imaging system in Australian conditions and critically compare the outcomes from the work with currently available technologies. A key aspect of the project was the assessment of the likely impact the imaging system has on current practices and recommendations for improved methods of geotechnical assessment in underground operations.
A comprehensive field-testing program of the SBS was undertaken to evaluate its suitability for application in Australian conditions. Test work was completed at BHPB Illawarra Appin Colliery and Xstrata Coal Tahmoor Colliery.
The Slim Borehole Scanner (SBS) was found to be a useful tool for enhancing the capability of Australian underground mine operators to assess roof conditions. The SBS is a significant advance on existing qualitative assessment methods such as the Borescope, and is complementary to existing direct measurement methods such as Tel-tales and Gel-extensometers.
The system proved to be easily deployed by 1-2 individuals and would best be applied on a discretionary basis by geotechnical engineers as an investigative tool. A clear advantage of the SBS is the ability to develop a database of roof conditions in digital form that can easily be contrasted and compared between sites and over time.
The SBS could provide a useful aid to the implementation of the CMRR system through the provision of reliable fracture intensity data. The SBS is also potentially complementary to the GRR (Geophysical Roof Rating) System developed by ACARP Project C15019.
The tool is robust and practical as is, and is immediately useful to Australian mining operations. It is suggested however that work is undertaken by the manufacturer to streamline a mechanical insertion process for the SBS, and to ensure that reliable depth encoding is ensured.
The use of the SBS system is likely to deliver the following benefits to the Australian underground coal industry:
- Improved means of carrying out quantitative analysis of roof behaviour;
- Improved understanding of roof properties and changes through time;
- Advance notice of potential roof stability issues;
- Reduced risk of unexpected gateroad failure; and
- Provide an objective digital record of roof properties.
It is recommended that the SBS system undergo Australian intrinsic safety approval and be adopted as a routine part of the geotechnical engineer's arsenal in assessing roof control issues in Australian mines.