MPBX-RST multi-point borehole extensometer

Overview

The Multi-Point Borehole Extensometer is used to determine stability and movement behavior in soil and rock masses. It can be deployed with 1 to 6 anchors to obtain a movement profile over depth relative to a baseline measurement and can be monitored using a readout or a data logger.

A typical borehole extensometer consists of a reference head, usually installed at the collar of a drill hole, and one or more downhole anchors placed at known depths. As the soil or rock deforms, the distances between adjacent anchors and between each anchor and the reference head change. This makes it possible to determine the distribution, magnitude, rate, and acceleration of deformation in the intersected rock or soil mass with accuracy.

Configuration criteria

The number of anchors and installation depths should be selected according to site geology, structural geometry, and other project-specific details. The use of two or more anchors at different depths allows engineers to distinguish potentially dangerous deep-seated movements from more trivial surface spalling.

Operational advantages

• Accurate and reliable measurement.
• For rigid rod extensometers, anchor lengths can be varied in the field.
• Different anchor designs are available to suit varying ground conditions.
• Rugged equipment that is easy to install and simple to operate.

Applications

It is aimed at civil infrastructure, energy, surface mining, and underground mining projects where internal deformation of soil and rock must be tracked in instrumented boreholes.