Acceptance Criteria for and Capabilities of Liners for Mitigating Ground Falls in Mines
| Principal investigator(s): | James F. Archibald (Queen’s University) |
| Co-investigator(s): | P.T. Katsabanis (Queen’s University) |
| Sponsoring Institution: | Queen’s University |
A paper based on this research was presented by Dr. Archibald at the Mining Health and Safety Conference in 2001. The paper is available as a pdf at http://www.mine.queensu.ca/people/faculty/Archibald/MASHA2001paper.pdf.
A list of Dr. Archibald's other papers that are very closely related to this research project is available at
http://www.mine.queensu.ca/people/faculty/Archibald/
For more information about this study, please contact James F. Archibald: archibal@mine.queensu.ca
Results
All polymer and like conventional area support products, such as shotcrete and fibrecrete, tested in this Phase II study have demonstrated capabilities for generating highly effective area support potential, especially when viewed in comparison with rockbolt and bolt-and-mesh restraint, which exhibit little capacity for mitigating rockburst damage. The entire range of polymer lining types evaluated has demonstrated an ability to deform substantially, undergo minimal layer damage, and to constrain fragment or loose rock ejection created by energetic rock breakage due to blasting as a method for rockburst simulation. In so doing, these tenaciously adhering, deformable cover materials have also demonstrated an ability to substantially mitigate damage often seen to result when catastrophic unsupported rock failure occurs. Shotcrete support, while demonstrating significant capacity to restrain rock heave and fragment ejection, was noted to suffer generally greater layer damage and potential breakup than any of the spray-on polymer materials. Rockbolts and bolt-and-mesh support media provided least effective support restraint in terms of reducing fragment ejection, restriction of the extent of the damage zone formed and prevention of damage to support materials.
Conclusions
The study results have validated the premise that new and innovative thin, spray-on lining (TSL) media may provide equivalent or substantially better rock support resistance than do conventional methods in the presence of dynamic rock failure.
Objective
The need to supply effective area ground support is important when it is realized that one third of all fatal accidents and a large proportion of serious injury incidents that occur in hard rock mines in Ontario result from falls of ground and rockbursts. One way in which injury reduction may occur will be through use of rapidly-deployable spray membrane support media, commonly designated as thin, spray-on linings (TSL’s) or polymer coatings. A research effort for the Workplace Safety and Insurance Board (WSIB) has been completed to assess capabilities of innovative, spray-on polymer and
like liner materials for providing satisfactory structural support for rock surfaces in underground hard rock mines. Substantial characterization work of polymer liner materials was achieved during Phase 1 laboratory trials, with systematic validation of lining performance occurring through completion of Phase 2 field scale support trials. This submission presents a summary of research which has been conducted for the second phase of this effort.
Method
In Phase 2, large scale blasting trials, to simulate rockburst events, were undertaken to test the effectiveness of spray-on liner and conventional support materials for mitigating dynamic rock ejection hazards created by such events. A total of 17 different support media types were subjected to near-identical blasting influence in a highly homogeneous rock material in order to create rock damage and support responses typical of those which would be experienced during actual, in-situ rockburst events. Direct comparison of rock and support media physical conditions was used to assess liner capacities to restrict rock movement and mitigate potential damage associated with dynamic rock failure. Blast conditions, damage yields and support agent capacities for restraint were observed photographically and by use of seismic monitoring techniques.
Reinforcement performance of the various media was assessed on the basis of support capacity to:
- provide resistance to seismic shock without losing adherence to rock surfaces onto which support material application has been made,
- exhibit capabilities for undergoing significant deformation without substantial cracking, tearing or loosening of the applied substrate layer,
- restrain broken surface rock fragments in place,
- minimize rock displacements away from blast sources, where restraint is shown to be ineffective,
- restrict the zone of surface rock damage through provision of surface confinement.
Publications
Archibald, J. F., 2003. "Effectiveness of Conventional Support Systems and Polymer Spray-On Liners for Reducing Hazards Associated with Rockbursting". Presented at the Mining Health and Safety Conference 2003, Sudbury, Ontario, April 22-24, 2003.
Archibald, J. F. and Katsabanis, P. T., 2003. "Comparative Evaluation of Shotcrete, Fibrecrete and Thin, Spray-On Polymer Liners for Blast Damage Mitigation". Presented at the 105th Annual General Meeting of the Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, Quebec, May 4-7, 2003. |
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