Monitoring: the key to effective ground control

However, according to Dr Peter Fuller, senior principal at specialist consultancy Coffey Mining, ensuring that ground support programs are behaving as expected is not always a simple task and often requires a substantial investment of time for mine operations’ staff.
“Mine operators need to measure two key components to assess performance of a ground control system: ground behaviour and roof support behaviour. However without reliable performance monitoring, the overall effectiveness of a control system cannot be managed.”
According to Dr Fuller, who has more than 35 years of experience in ground support selection, to date there has been a number of geotechnical instrumentation and monitoring system suppliers in the market to assist miners with various aspects of monitoring and measurement. But, Dr Fuller said that choosing exactly which system or systems were optimal for a particular application could be both confusing and time consuming.
“Traditionally, a geotechnical engineer on site would identify the need for a ground control monitoring system and spend days researching and sourcing the equipment required,” he said.
“Then they would need to install it, work out how to get it connected to a data logger, how to read the data, and finally interpret the raw results into meaningful information on ground behaviour and support performance.”
According to Simon Bailey, instrumentation and monitoring services manager at Coffey Mining, a substantial amount of time and money can be saved by engaging a single service provider to handle all requirements involved in measuring the performance of ground control programs.
“The process typically involves selecting and designing the arrangement of instruments around the performance monitoring required by the mine, designing and installing the system, collecting and processing the data, and then interpreting the data for the client.”
Bailey said that due to the skills shortage in the mining industry, especially for mine geotechnics professionals, mine operators are partnering with specialist consultants to provide expertise and support to their technical staff. Over the past three years, his team has been heavily involved with the instrumentation of the Beaconsfield Gold Mine in Tasmania.
“To ensure that the systems accurately mirror the ground support used in the mine, we’ve designed two custom instruments specifically for Beaconsfield: the first is an instrumented SMART Cable with a debonded length and plating setup to match the energy absorbing and deformation capabilities of the cables used on site. The second is an instrumented rock bolt with the gauge positions matched to the bonded portion of the bolt.”
Both instruments allow accurate assessment of support performance to be made.
“The beauty of these instruments is that after training, they can be installed quickly using standard procedures and machines, which is something you don’t see every day, as instruments would usually require specialist installation.”
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 the information they really need.”
Peter Hills, technical services manager at the Beaconsfield mine agreed: “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.
“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.”
Simon Bailey said he firmly believes that remote live data collecting is next “big thing” in mine geotechnical instrumentation and monitoring.

About Coffey Mining
Coffey Mining is a global specialist consultancy providing a wide range of technical services and products to all sectors of the international mining industry, from target generation to mine closure. Coffey Mining is a subsidiary of Coffey International Limited, a listed company (ASX: COF) with over 4,000 people working on projects in more than 80 countries and permanent offices throughout Oceania, the Americas, Africa, Asia and Europe.
For more information visit: www.coffey.com