An innovative, non-destructive approach to rock bolt monitoring is proving the power of IoT for mining safety.

“Safety first” is the watchword in the mining sector and it’s not without a reason. While the exact number remains unknown, experts estimate there are around 20,000 mining deaths globally each year. According to the International Labor Organization (ILO), mining accounts for 1% of global employment, but is responsible for 8% of fatal incidents. And these statistics haven’t covered innumerable cases of nonfatal lost-time injuries. Given the significant financial and human costs alongside lost productivity, the possible economic impact of a mining worksite incident can exceed US$ 5 million.

The Impending Danger of a Mine Roof Collapse

Among countless potential hazards, an underground roof collapse is a commonly faced issue. In the US, it contributes to roughly 50% of total underground deaths. The number of incidents is vast, but there’s one common underlying cause – rock bolt failures.

The mining sector extensively relies on rock bolts to support and stabilize the structure of underground cavities. Mounted into mine roofs, these steel rods bind the rock mass together to avoid deformation and ensure mine solidity. Their failures can lead to disastrous roof falls, costing workers’ life and incurring substantial expenses for companies.

Under the harsh impact of continuous seismic events and corrosive groundwater, rock bolts are at high risk of fractures, rusting and corrosion that degrade their load-bearing capacity. Monitoring the integrity of these reinforcement pillars is critical, yet, remains a significant challenge.

Conventional options have been limited to either visual checks or removing the bolts from the rock mass for inspection. Needless to say, both are nonoptimal with the latter inherently inefficient and complex, not to mention the risk of permanently damaging the bolts. The resulted lack of visibility leaves both mining operators and workers with an obscure picture of underground conditions.

A Non-Destructive Approach to Rock Bolt Monitoring

The new wave of smart sensor technologies brought by the Internet of Things (IoT) is now opening the door to effective and non-destructive rock bolt monitoring. Built into the bolts, these sensors automatically capture multiple readings on their structural and operating conditions. For example, vibration and strain gauges distributed along a bolt detect excessive seismic events and loading levels that potentially damage its integrity. Likewise, ultrasonic sensors identify abnormal sound waves that indicate a crack or delamination issues.

Embedded with a communications module, IoT sensors wirelessly transmit these readings to an on-premises control system. With the setup of an automated workflow, workers can be alerted to the danger of undergoing deformation. This enables timely corrective actions to circumvent catastrophic failures of the entire rock mass.

Taking a step further, mining managers can even improve future ground control practices with contextual information from IoT data. Long-term analysis of historical defects and seismic activities reveal more accurate insights into degradation patterns and service life of the ground support system. This allows for relevant adjustments in system design, as well as the level of drilling and excavation activities to enhance operational safety.

Looking Ahead

The potential of IoT for mining safety is enormous and its application in rock bolt monitoring is the compelling evidence. Development of smart rock bolt sensors is on the way and their implementation will ultimately require several conditions to be fulfilled.

For companies to quickly extract values out of it, an IoT-based rock bolt monitoring system must be cost-effective, easy to install and manage. As the bolts are firmly embedded in the rock mass, sensors must be able to operate for years without battery replacement. Above all, high data reception rate must be guaranteed in hostile underground environments with extreme depths and nonsymmetric topography.

Eventually, all of these requirements boil down to the need for highly robust, cost-effective and power-efficient connectivity.