Vibrating Wire Soil Extensometer

The Vibrating Wire Soil Extensometer measures lateral deformation of soil and rock, particularly in embankment dams and quarry or mining excavations.

A chain of successive displacement transducers and anchor beams may be employed to provide a continuous profile of movement. The Extensometer consists of a Vibrating Wire displacement transducer contained within a heavy-duty sealed housing.

A telescoping PVC sleeve protects the extension rod from soil contact, ensuring its free movement.

As lateral movement occurs, the distance between the VW transducer and the anchor is changed. This causes a change of frequency in the VW transducer; the change is measured and can be converted to give the displacement in millimeters.

Product Features 

  • Accurate, robust and very good long-term stability
  • Heavy duty steel housing suitable for burial in rock-fill
  • Suitable for remote reading
  • Over-voltage surge arrestor fitted to protect against electrical damage
  • Connecting cable is strong, flexible, armoured and can be used in lengths in excess of 1000m
  • Waterproof and sealed to 1000kPa

Product Benefits

  • Suitable for remote reading and datalogging
  • Very heavy duty
  • Accuracy unaffected by cable length
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The Soil Extensometer is connected between two anchor beams.

Any displacement between the anchor beams will cause movement to the VW transducer, via its connecting rod. This changes the tension in the vibrating causing a change in frequency.

The resulting displacement can then be measured in mm.


The measurement of soil and rock movements including:
  • Horizontal and vertical displacements within embankment fill material
  • Displacements of retaining walls and abutments
  • Foundation spreading
  • Control of natural and cut slopes, quarry and mining excavations


Please contact us directly for further information or to speak with one of our product experts.