Slope Stability and Underground Convergence Monitoring

Survey mine closure case study


Maptek Sentry is a mobile remote monitoring system that uses laser scanning to continuously measure ground movement with extremely fine spatial resolution and accuracy. Sentry can be applied to surface stability monitoring and underground convergence prediction applications.

Sentry is flexible and cost-effective for monitoring risk due to the combination of a mine-specced R3 laser scanner with sophisticated software to monitor and analyse movement over time. This can be deployed in a mobile, open pit configuration with inbuilt power and communications, cellular and wifi networking, a stable bollard for mounting the laser scanner and Sentry software.

Sentry helps personnel monitor and report on movements and predict failures, to maximise the safety of personnel and equipment. Applications include mining and civil engineering projects, including road cuttings, land slips, dam walls and tunnel openings.

Periodic monitoring with the laser scanner in Sentry ‘patrol’ mode mounted on a tripod, wall or bollard allows large scenes to be quickly captured, helping to determine zones to watch more closely. Continuous monitoring can then be used where conditions pose the greatest risk, providing accurate real-time data to guide safety management programs.

The advantage of Sentry over radar systems is the ability of the laser-based system to measure changes resulting from both rapid and gradual movement. Monitoring frequency and notification thresholds are fully customisable, providing accurate results for mine design and planning. Sentry supports continuous surface monitoring required by geotechnical teams and mine management for managing risk in open pit mining and quarrying operations.

Sentry monitors and maps the complete scene, producing a true 3D terrain model for dynamic viewing. This adds value and context to the data which can be reported as displacement, velocity and inverse velocity graphs.

Operational flexibility is a key benefit of the Maptek spatial measurement approach. The Maptek R3 laser scanner can be removed temporarily for other survey tasks. When set up repeatedly over the same fixed location sites can maintain a continuous monitoring history. The high resolution laser scan data can also be brought into PointStudio for rockfall volume calculations and geotechnical analysis. This has proven to be a key advantage in supporting geotechnical engineers to balance pit wall design with operational safety.

Sentry is ideal for monitoring subsidence and convergence in underground mining and civil tunnelling operations. The underground system combines the compact short range IP65-rated Maptek SR3 laser scanner deployed to safely collect sub-millimetre accurate data in periodic or real-time mode with Sentry software. A built-in alignment laser ensures accurate backsighting, and the resection capability enables the same laser scanner to be used for routine underground survey tasks. Intuitive fast setup and operation minimises time underground.

Sentry provides reliable surface monitoring in extreme environments, with continuous operation in temperatures from -20°C to 50°C, and for a limited operational time below -20°C.

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