Extensometers are used to measure the displacement or general deformation of rock, soil, and concrete structures in a variety of geotechnical applications. Precise measurement of changes in distance between one or more anchors generates up-to-the-minute data concerning the distribution, magnitude, and rate of ground and structure deformation.
The use of Extensometers in excavations or major constructions allows for constant monitoring of structural displacement and deformation due to shifting ground conditions, structural strain, and other forces. Extensometers can also be used to monitor changes in the settlement or heave of the ground surface due to excavations and new constructions. They are an important tool for ensuring the safety of underground operations such as tunnels, mines, and major excavations.
Multi-Point Borehole Extensometers (or MPBX) are rugged and easy to install, consisting of a surface-level reference head and one or more anchor points embedded in a borehole and connected to the reference head by rigid or flexible rods. Multiple anchors record changes in distance in relation to each other and the reference head. Higher anchor count and spacing yields increasingly precise data related to ground deformation.
The Vibrating Wire Inline Extensometer is primarily used in below-ground applications such as tunnels, dams, open pit mines, and underground caverns. It is also commonly used underneath Embankments for a comprehensive settlement ground profile as you can benefit from the lack of headworks provided with this system. These extensometers are fully enclosed assemblies consisting of multiple extension sections assembled together in series. Unlike conventional Borehole Extensometers, the Vibrating Wire Inline Extensometer is installed flush with the ground surface, and due to its multi-point, series-connected design, it provides a greater range of measurement than the standard Borehole Extensometer.
Soil Extensometer arrangements can also be provided for horizontal requirements for displacement profiles from one structure to another.
All Extensometers provided by RST Instruments are compatible with the wide range of Data Logger solutions such as RSTAR Affinity, and visualized via either the RSTAR Affinity Data Visualization platform or NavStar GeoExplorer software for a complete end to end solution.
I’m very happy with the quality of the instrumentation and technical support from RST, as always. They worked with us from the initial stages of the project to ensure that we were fully prepared and equipped to use the RSTAR network for the first time. They delivered everything within the tight project time frame to ensure that there were no delays on site, and the submersible tilt meters looked like new even after over twelve months of being submerged in Thames water!
-Richard Lipscombe, BEng (Hons), Director & Principle Consultant - RL Geotechnical Ltd
