Borehole Rod Extensometer

The borehole rod extensometer is a low cost but reliable instrument used to transmit all anchor displacements from failure planes in rock or zones of movement in soil masses to a collar reference plate via mechanical or electrical readings.

The extensometers are commonly installed in natural or cut slopes to monitor slope stability and can even detect settlement when installed appropriately.


The borehole rod type extensometer is used to measure and locate settlement, displacement and deformation in soil and rock.
It consists of a reference head and one or more in-hole anchors each of which is placed at a known depth and connected to the reference head by either a rigid or flexible rod running inside a flexible sleeve, which keeps the rod de-bonded from the grout.

As the soil or rock deforms the distances between the in-hole anchors change, as do the distances between the individual in-hole anchors and the reference head. The magnitude, distribution, rate and acceleration of deformation can be accurately measured at the reference head.
Our extensometer range is available in a wide variety of reference heads, anchors, rods and measuring sensors.