Mining companies need to pay increasing attention to geotechnical and microseismic monitoring if they are to reap the full benefits of support performance systems that manage ground control to improve the operational safety of a mine, according to Simon Bailey, instrumentation and monitoring services manager at Coffey International Ltd.’s subsidiary, Coffey Mining. By collecting and analyzing data on actual rock mass behavior, this provides valuable evidence in undertaking appropriate risk assessments for operations.
“The best results in ground control assessment are achieved through continuous monitoring of in-place geotechnical instrumentation once the ground control measures have been designed and installed,” said Bailey. “By continuously feeding data back into the ground control design, and using remote instrumentation for real time results, we are able to receive a greater amount of information that has a higher degree of reliability, allowing us to make more informed judgments about what is happening within a mine.”
Coffey Mining’s specialists have been successfully designing, installing and managing geotechnical instrumentation systems on mine sites for more than 35 years. This has recently included remote monitoring systems.
Bailey said that although the instruments require upfront capital costs, the effectiveness of these systems is resulting in a significant increase in the operational safety of the mine and a reduction in ongoing production costs.
“Real time monitoring allows us to better understand how the ground is behaving and how we can select the best support systems possible. After many years of experience in this area, we know that real time monitoring significantly reduces safety risks and allows us to address potential risks in ground stability more quickly. Remote live data collecting is the future of mine geotechnical instrumentation and monitoring,” he said.
According to Adrian Penney, senior geotechnical engineer at Coffey Mining, geotechnical monitoring also needs to be integrated with microseismic monitoring to allow the response of the rockmass to mining to be characterized.
“Microseismicity provides a window into the behavior of the rockmass remotely from the excavations, and can help to verify mine design parameters. Seismic monitoring also allows the identification and hazard assessment of seismic domains. This assists with assessing potential hazards and implementing risk reduction measures. With integrated geotechnical and seismic data analysis, the cause of deformation around excavations can be better understood, and allows for future predictions of ground behavior to be made with increased confidence.”
Over the past three years, Coffey Mining has been heavily involved with the instrumentation of the Beaconsfield gold mine in Tasmania. According to Bailey, the system designed and implemented at Beaconsfield provides real time data at the mine office and live data direct to Coffey Mining’s office in Melbourne, allowing the possibility of real time data interpretation.
“Basically the client doesn’t have to worry about collecting the data because the system we provide comes complete with the methodology to get the data back to our office. We can monitor the data and provide the clients with the information they really need. We manage the monitoring database and also record the health of the monitoring system. So we know if anomalies in the data are due to the behavior of the rockmass, or due to system problems, even years later.”
Peter Hills, technical services manager at the Beaconsfield mine agrees. “Remote ground control performance measurement has significantly simplified the process of monitoring our ground control systems and now allows re-entry risk assessment to be carried out in a timely manner,” said Hills. “Now, with just the one supplier providing and well placed to assist with the maintenance and operation of our monitoring system, we have confidence that the total system performance is as required, and a second opinion can be quickly offered on any issues we perceive.”
“At the end of the day, there’s no point having good data if you don’t harness the critical information it provides. The key to effective ground control comes down to well-designed instrumentation, continuous monitoring and ready access to the information at hand,” Bailey said.