Convergence Monitoring

The uGPS Rapid Mapper™ produces accurate data for convergence monitoring purposes.

Convergence MonitoringFor many underground mines, regular convergence monitoring is essential to ensure safe and productive mining activities with minimal delays or interruptions. Areas of concern, such as extraction levels for block caving operations, should be monitored and assessed on an ongoing basis.

Most underground mines use a combination of visual inspection and manual measurement techniques (e.g. distometer or measuring tape readings) for convergence monitoring. Some mines use a network of extensometers to augment their understanding of rock mass movement beyond the tunnel walls to aid in convergence prediction. While these practices definitely do have their place in an overall monitoring strategy, they do also have limitations.

Visual inspections and manual measurements are subject to human error– they can be subjective and inaccurate, and of course, require a large amount of human exposure in hazardous environments. Extensometers, especially those with electronic read-out heads, are more accurate and can provide valuable early indications of convergence-related issues. However, they are very selective and localized in what they measure. It would take a significant number of extensometers to monitor convergence across every part of a single tunnel or cavity, and installing that many would be very costly and impractical.

By comparison, using the uGPS Rapid Mapper™ 3D mobile mine scanner as a source of data to be used for convergence monitoring purposes has many advantages, including:

  • The scanner can easily create dense 3D point cloud data that can be meshed to provide geotechnical engineers with thousands of geometric measurements. If another scan is made of the same area the next day or week, the results can be superimposed over the original scan and any differences noted. In this way, a mobile scanner can operate alongside, and often yield more accurate results than, an extensometer network.

Because it uses 3D laser-based scanning, even highly complex or inaccessible parts of tunnel or cavity walls and roofs that would be hard to visually inspect or install extensometers in can be quickly, easily and accurately scanned.