Continuous Rod Extensometer Overview

The Continuous Rod Extensometer system accurately measures settlement and/or heave at single or multiple anchor points in a borehole and at its reference head.

The Continuous Rod Extensometer system accurately measures settlement and/or heave at single or multiple anchor points in a borehole and at its reference head.

The system employs up to eight rods, anchored along the axis of a borehole, terminating in the reference head at the borehole entrance.

Displacement along the axis of the borehole from the anchor is recorded by measuring movement of the top of the rod relative to the reference head.

The Continous Rod Extensometer is pre-assembled to specified lengths.

A versatile range of options are available for Continuous Rod Extensometers:
  • Automatic or manual reading
  • Hydraulic anchoring for soil
  • Groutable anchoring for rock
  • Multiple or single point rod reference
Continuous Rod Extensometer Data Sheet
File Size: 812 kb
File Type: pdf
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Continuous Rod Extensometer User Manual
File Size: 986 kb
File Type: pdf
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Product Features
  • Rods and anchors are delivered pre-assembled to customer specified length
  • Various anchor types available according to soil conditions and installation method
  • Manual or remote monitoring
  • Remote option uses Vibrating Wire or potentiometric displacement transducers
  • Up to 8 measuring points per borehole

Product Benefits
  • Installation in drillholes or boreholes at any orientation
  • Quicker installation than conventional rod extensometer systems
  • Fibreglass less sensitive to temperature changes than steel
  • Particularly useful in confined areas
  • For borehole diameters up to 200mm

Operation
Relative movement between the end anchor and the reference tube is measured with either a digital depth gauge, or a displacement transducer inserted through the reference tube and registering on to the free end of the rod.

The ground condition determines the type of anchor to use:
  • Groutable anchors for downhole installation in rocks
  • Hydraulic type anchors (single or double ended) for soft soils
  • Packer anchors for jointed rocks, where there is flowing water, or uphole installations
The extensometers have reference heads with provision for up to eight measuring points per borehole. Borehole diameters may be in the range of 100mm-200mm.

Application
Continuous Rod Extensometers are used to monitor small scale rock and soil movements to a high degree of accuracy, including settlement and heave of foundations, the relaxation or subsidence of rock around tunnels, shafts, caverns and abutments.

Typical applications include:
  • Monitoring settlement and heave in foundations
  • Monitoring tunnels, shafts, caverns and abutments
  • Control of natural and cut slopes, quarry and mining excavations
  • Monitoring deformation of retaining walls, bridge piers and abutments

Technical Rating
As the correct installation of any monitoring sensor or system is vital to maximise performance and accuracy, Geomotion makes the following recommendations for the skill level of the installation contractor.

Technical Rating for this Product:  ADVANCED

The installer is trained and experienced in the installation of this type of instrument or systems, and is ideally a specialist Instrumentation and Monitoring contractor.

Geomotion offer installation and monitoring services to support this system. For more information please contact us.