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| Monitoring rock failures and roof movement to warn of roof falls |
Background
Currently, miners have little, if any, warning of impending roof falls. NIOSH is in the process of deploying several monitoring systems at mines with known roof fall problems so that an extensive database of measurements of microseismic emissions, roof-to-floor convergence, and roof beam sag can be compiled. These mines have very diverse geologic conditions and stress regimes and are mined with different methods. Several years will be needed to collect enough data to prove or disprove adequately the validity and feasibility of this technology. Field sites will be added in the future to broaden NIOSH’s database. This exhaustive scientific study will identify the precise trends capable of forecasting roof falls and define their limitations.
The goals of this project are to:
- Increase our fundamental knowledge of how roof falls behave,
- Develop and evaluate sensor-based roof fall warning technology, and
- Document the amount of time available to warn miners prior to a roof fall.
This research is aimed at increasing roof fall forecast times and location accuracy.
Potential Outcome
A sensor-based system composed of microseismic emission and roof beam deflection monitoring instruments has been developed. To date, this technology has successfully forecast events approximately 50 minutes ahead. Two field trials are currently underway.
Currently, all our research is being focused on the following research question: Can monitoring technology be used to increase the time between the recognition that a particular area of unstable roof rock is going to fall and the actual moment it begins to fall?
The research will be successful if it shows that a forecast window does exist and can be lengthened using a sensor-based monitoring system. Project results will then be formulated as guidelines for installing and using roof fall monitoring systems. With these systems, mine operators will be better able to identify those areas at high risk for roof falls and remove workers or take other corrective action before a roof fall occurs. The result will be to lower miner exposures to hazardous conditions and decrease roof fall injuries.