MINING GROUND SUPPORT

Mining Ground Support- Seismic Monitoring

Mining has always been an industry where risk is balanced against reward, and safety is played against cost. But with pressure mounng on global corporaons to demonstrate due diligence, seismic monitoring is coming to the fore. If one thing has remained a constant throughout the history of mining, it is ground support. While techniques and technology have changed beyond recognion, the theory remains the same: no ground support, no mining – or at least no mining without serious risk to your health. Subsidence and sinkholes are the surface effects of soluon mining. Apart from damage to economic producon, such events are now of environmental concern. The control of cavity evoluon and its effect is thus a problem which requires serious examinaon. Seismic acvity can impact underground mining operaons and the associated surface infrastructure in several ways, from the damage caused by naturally occurring earthquakes to rockbursts, the explosive fracturing of rock in a mine sha that may be caused by natural or induced seismicity. Despite the serious dangers, the majority of mining operaons, even in seismically acve regions, take few precauons to migate the risk or monitor seismic acvity. Although mine operators could be forgiven for assuming that earthquakes and similar natural events represent a risk that is impossible to predict or guard against, opons exist and are being implemented in other industries.

UNDERSTANDING MINE SEISMICITY

The key to a mining operaon is to understand the seismicity of rock mass, with the primary purpose of creang good ground support to maintain safe excavaon. Seismic monitoring equipment is used in order to idenfy both potenal hazards caused by changing ground condions, and to maximise mine producon through prevenng seismicity related delays. Seismic monitoring helps locate areas where rock mass failure is causing seismic events. A seismic event can generally be described as the vibraon of rock, slipping or breaking, something common in an underground mine seng, with constant drilling and blasng. While most seismic events are minor, stress change events for example rarely register more than 0 – 0.5 in Richter magnitude, larger events, such as fault slips, can register as much as up to +5 and cause considerable damage to operaons. By understanding rock mass behaviour, mining companies can begin to assess the size of any potenal hazards.

HOW IT WORKS

Advanced microseismic sensors and ltmeters are installed at strategic places around a mine to measure ground vibraons. These are then picked up by a digital seismic data recorder that acquires and processes the data to build an accurate picture of seismicity through 3-D modelling techniques. Data is connuously transmied to the surface and can be accessed through the internet in realme from anywhere on the planet. It is not all about safety either, for if mine operators increase their knowledge of the rock mass, they can enhance producvity through reducing downme and deploying their workforce away from areas that are experiencing heightened seismic acvity. Mine design is another area that benefits from microseismic monitoring; through understanding how ground condions are changing, mine design and sequencing can be opmised at an earlier stage in the life of a mine. If you were to cast an eye to the future however microseismic monitoring would be sure to loom large. In a growth industry driven by corporate giants where safety, problem solving and producvity are paramount, it cks all the right boxes.