Multipoint borehole extensometers

Ground movement around an underground excavation is not a problem to be prevented, it is a process to be understood. How the rock mass deforms, at what rate, in which direction, and whether that deformation is within the range the design assumed. These questions determine whether an excavation is performing as expected or approaching a condition that requires a response.

Aerial view of a yellow and blue piling rig with a long auger on red earth, beside a yellow steel beam and construction materials
Surveyor holding a survey pole on a gravel plain with low mounds under a cloudy sky

Measuring ground movement and excavation response

SCT measures ground movement and excavation response using instrumented arrays designed around the specific behaviour the ground in that environment is capable of producing. The data is interpreted in context, not logged and reported, but read against the design assumption and assessed for what it means for the decision the monitoring program was built to inform.

SCT’s instrumentation for displacement monitoring

4 Anchor Rock-IT 150mm (Gen2)

Rock-IT

A mechanical multipoint borehole extensometer for measuring roof and rib displacement at defined anchor depths, in 2-anchor or 4-anchor configurations. Simple, low cost, suited to routine inspection and management plans. An optional warning system accessory, the Rock-IT FLAG, is available for the 4-anchor.

The Rock-IT is an easily installed device used to measure displacement in four horizons about mine roadways. The layout and size of the reading indicators allow for fast, accurate and continuous measurement of strata movement.

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2 Anchor Clock-IT

Clock-IT

The same multipoint extensometer, with a dial gauge readout instead of a digital one — for sites where that format suits the existing inspection workflow.

Clock-IT is a low-cost, easily installed monitoring device that provides continuous visual indication of roof conditions. It is capable of resolving roof strata movement within two horizons, typically within the bolted roof horizon and above the roof bolts. Clock-IT is installed in holes up to 10m long (longer on request), across a range of hole sizes, and can be quickly and systematically installed by operators.

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Rock-IT combined with the RockSHIELD head unit

RockSHIELD

SCT's wifi-enabled digital monitoring system, connecting to displacement and shear instruments in the rockmass and transmitting data to surface via the mine's own network — removing the need for manual readings in hazardous areas.

Installing the RockSHIELD system enhances geotechnical monitoring capabilities. Monitoring is automated, a significant time saving, and data analysis and alerts provide early warning of changing roof conditions. In turn, enabling the removal of people from roof fall hazards.

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Applications for SCT’s displacement monitoring instrumentation

  • Systematic roof condition monitoring across active development headings, where consistent data collection is required without increasing exposure of personnel to unsupported ground.

  • Confirmation of support performance in a newly developed roadway, where displacement readings within and above the bolted horizon establish whether the installed reinforcement is controlling movement within the design assumption.

  • Continuous automated monitoring in a high-risk area where manual inspection is hazardous, with real-time data transmitted to surface and threshold alerts enabling a response before conditions deteriorate.

  • Long-term roadway condition tracking through the life of a panel, where deformation trends over time inform decisions about secondary support, roadway rehabilitation or extraction sequence adjustment.

  • Monitoring roof displacement ahead of a longwall installation where abutment loading is developing and early detection of movement outside the expected range allows support intervention before the condition escalates.

  • Establishing a deformation baseline in a new underground development where no prior ground behaviour data exists and measured displacement response is needed to validate the design assumptions before the next stage of work is committed.

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