Borehole Extensometer – EXCEXX-100

Borehole extensometers are instruments which record the rock mass displacements at certain points (anchor).  They are installed in a borehole and are fixed to the ground with different methods, either by grouting or mechanically by spider anchors.  Stability and movement behavior of structures in rock can be determined by these instruments.  A typical extensometer consists of a reference head, one or more anchors and rods by which the displacement of each anchor is transferred to the reference head.  These rods are usually made out of fiberglass which is light, strong and elastic.  A PE pipe covers all the rods and de-bonds them from the grouting agent.  When the soil or rock deforms, the distance between anchors change and these are recorded relative to the reference head. By using extensometers, one can accurately determine distribution of rock mass displacement along the length of extensometer and calculate the magnitude and rate of displacements.  Reading displacements can be either manually or remotely by attaching an electrical head with linear sensors.