A typical Borehole Extensometer consists of a reference head, usually installed at the collar of a drill hole, and one or more downhole anchors, each anchor being is in place at a known depth in the borehole. As the soil or rock deforms, the distances between adjacent downhole anchors change, as do the distances between the individual downhole anchors and the reference head. This allows an accurate determination of distribution, magnitude, rate and acceleration of deformation in the rock or soil mass intersected by the drill hole.
The number of anchors and anchor depths should be selected based on site geology, geometry of structures in the area, and other site-specific details. The use of two, or more, anchors at various depths allows the engineer to distinguish between potentially dangerous deep seated movements and more trivial surface spalling.

Product features:

• Accurate and reliable
• Anchor lengths can be varied in the field. * for Rigid Rod Extensometers only
• Various anchor type designs are available to suit differing ground conditions
• Rugged, easy to install, and simple to operate