In order to prevent a mine from collapsing, the mine's surface is anchored to the mountain with three meter long iron bolts. Iron bolts are used to stabilize cavities in the rock and annualy approximately 100 million bolts are installed around the world. But the bolts could break, for example, from seismic activity caused by explosions or tremors, and thus lose its bearing capacity. A technology that can detect that the bolts are broken, however, has not existed before, and it is unlikely that a broken bolt can be detected with the naked eye.
– Simply put, one can say that we provide a common rock bolt with Internet of Things (IoT) technology, says Jens Eliasson, Associate Professor of Industrial Electronics.
Increased safety in mines
By providing the rock bolt with sensors and allow for wireless communication, several different parameters can be monitored. For example, the sensors can detect if there is abrasion in the bolt and it is about to break. The sensors can also respond to vibrations.
– The sensor on the rock bolt analyzes deviations and can detect tremors and then send out a warning signal. That means increased safety for those who are in the mine, says Jens Eliasson.
Already today, there are instruments in mines that can warn of tremors, so called geophones. They are very precise but also very expensive. The smart rock bolts would be a complement to geophones, many more in number and consequently provide more measurement points at lower cost.
– Our goal is that the sensors will measure vibrations thousands of times a second, in very many places. One of our greatest challenges is the need for long battery life and large memory storage. We hope to achieve a battery life of between two and five years, and memory storage is already at 64 megabyte.
Warns and informs
All intelligent rock bolts are connected to a gateway that also can send signals to the bolts. Each rock bolt is also equipped with powerful LED lights in different colors. The diodes can serve as a warning or information system, and for example, lead the way to the nearest exit or signal that there is a risk of tremors. Another feature that is under development is positioning. Through interacting rock bolts, it would be possible to position someone or something located underground in a mine.
IPSO Challenge is a competition arranged by IPSO Alliance. Out of 50 entries, ten ended up in the semifinals and the smart rock bolt is one of these. Both semi-finals and final is decided in early December in San Jose, United States.
In addition to researchers from Luleå University of Technology, also Eistec, GrepIT, Malmfälten AB and Gluetech have been involved in the development of the intelligent rock bolt.
Follow the smart rock bolt on Twitter, @SmartRockbolt.