Vibrating Wire Inline Extensometer
The Vibrating Wire Inline Extensometer is used to determine the stability and movement behavior of soil, rock, and concrete structures.
The Vibrating Wire Inline Extensometer is used to determine the stability and movement behavior of soil, rock, and concrete structures. The main advantage of the extensometer is that it has no electrical head protruding out of the borehole, contrary to conventional multi-point borehole extensometers (MPBX). The Inline Extensometer is installed flush with the borehole collar or ground surface and measures movement at different depths in the borehole.
By construction, all displacement transducers are located in the borehole in sealed head/anchor assemblies that are inserted in the borehole and separated by extension sections which can be of variable length depending on the required measurement depths. The extension sections consist of rigid 3/8 inch (9.5 mm) stainless steel rods protected by a telescopic outer 21/32 inch (16.8 mm) PVC pipe. The larger diameter of the rigid rod is an additional advantage as compared to the usual 1/4 inch (6.35 mm) of conventional MPBXs, as it provides more accuracy in the measured displacements, both in case of extension and compression movements.
As all displacement transducers are in series in the borehole, the total measurement range of the extensometer is the sum of the individual measurement ranges of each transducers. This allows to measure considerably larger movements than conventional MPBXs while using lower cost standard range transducers.
|Sensor Range||25, 50, 100, 150, 200 mm|
|Accuracy||+/- 0.25 % FSR|
|Thermal Zero Shift||<0.05% FSR/°C|
|Operating Temperature||-20°C to 80 °C|
|Extensometer Head max/min Diameter||63.5 mm / 42.5 mm|
|Signal Cable||Two twisted pair cable with polyurethane jacket (one cable per measurement point).|
Vibrating Wire Inline Extensometers are commonly used for:
View illustrations on how the Vibrating Wire Inline Extensometers are used in underground mines.
|EXTENSOMETER HEAD & ANCHOR ASSEMBLY*||PART #||GAUGE LENGTH|
|25 mm||EXINLINE-1025||1 m|
|50 mm||EXINLINE-1050||1 m|
|100 mm||EXINLINE-1100||1 m|
|150 mm||EXINLINE-1150||1.5 m|
|200 mm||EXINLINE-1200||2 m|
*-Please specify anchor type
*-Includes Signal Cable & Sheath
|Groutable Anchor with Spring Legs||EXIL12000|
|Hydraulic Borros Anchors||EXIL13000|
|Hydraulic Bladder Anchor||EXIL14000|
|Number of anchors, type and depths.|
|Specify sensor range.|
|Extension or compression expectations.|
|Drilling method, soil and/or rock types.|
|Orientation of borehole.|
|Grout and/or bleed tubes.|
|Hydraulic pump for anchors.|
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