Evaluation of acoustic attenuation as an indicator of roof stability in advancing headings

Abstract A novel acoustic technique developed to monitor roof stability in advancing headings was evaluated during a field monitoring trial at the Brunswick Mine, New Brunswick, Canada. The acoustic technique uses waveforms generated by mining activity near the active face (such as rotary-percussion drilling for the installation of support or drilling blast-holes) to identify changes in the attenuation properties of the roof rock mass which are correlated to stability through conceptual models and independent experimental work. Field trial results indicate that (a) the selected frequency range of the acoustic sensors is suitable to ensure that recorded waveforms have originated within the rock mass volume of interest near the face of the active heading, (b) the waveforms generated by rotary–percussion drilling are sufficiently consistent to be considered as a stable acoustic source, and (c) observed changes in roof attenuation are consistent with what would be expected in response to the installation of support near the freshly blasted face and blast-hole drilling of the face.