File Name
Vibrating Wire Inline Extensometer
Resource Type
Brochure| Language | Version | Download |
|---|---|---|
| English | EXB0020G |
|
| Spanish | EXB0031A |
|
Vibrating Wire Inline Extensometer
The Vibrating Wire Inline Extensometer is used to determine the stability and movement behavior of soil, rock, and concrete structures within a borehole at desired depths/elevations relative to a point of reference.
Overview
The main advantage of the Vibrating Wire Inline Extensometer is that it has no electrical head protruding from the borehole, unlike conventional Multi‑Point Borehole Extensometers (MPBXs). The Inline Extensometer sits flush with the borehole collar or ground surface and measures movement at multiple depths relative to a designated reference point.
All displacement transducers are housed within sealed head/anchor assemblies installed in the borehole. These assemblies are separated by extension kits of varying lengths, depending on the required measurement depths. The extension sections use rigid 3/8‑inch (9.5 mm) stainless steel rods protected by a 1/2‑inch (12.7 mm) SCH40 PVC sheath. The larger rod diameter—compared with the 1/4‑inch (6.35 mm) rods commonly used in conventional MPBXs—provides increased accuracy for both extension and compression movements.
As all displacement transducers are installed in series, the total measurement range of the extensometer equals the sum of the individual transducer ranges. This allows the system to measure significantly larger movements than conventional MPBXs while using lower‑cost, standard‑range transducers.
VIBRATING WIRE INLINE EXTENSOMETER SPECIFICATIONS
| ITEM | SPECIFICATION |
| Sensor Range | 50, 100, 150, 200 mm Other ranges available on request |
| Accuracy | +/- 0.1 % FS |
| Resolution | 0.025% FS |
| Linearity | <0.5% FS |
| Thermal Zero Shift | <0.05% FSR/°C |
| Operating Temperature | -20°C to 80 °C |
| Min. Borehole Diameter | 75 mm |
| Signal Cable | Two twisted pair cable with polyurethane jacket (one cable per measurement point). |
Vibrating Wire Inline Extensometers are commonly used for:
- Ground movements around tunnels.
- Deformation of concrete piles (tell-tales).
- Deformations of dam abutments and foundations.
- Ground movement behind retaining walls, sheet piling, slurry walls, etc.
- Ground movements in the walls of open-pit mines.
- Fracturing in the roofs and walls of underground caverns.
- Subsidence above tunnels and mine openings.
- Settlement and heave of foundations in soft soil.
View illustrations on how the Vibrating Wire Inline Extensometers are used in underground mines.
Vibrating Wire Inline Extensometer Ordering Info
| EXTENSOMETER HEAD & ANCHOR ASSEMBLY PLEASE SPECIFY ANCHOR TYPE |
PART # | GAUGE LENGTH |
| 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 |
Extension Kit Lengths
| ITEM | PART # |
| 0.5 m | EXIL-0500 |
| 1.0 m | EXIL-1000 |
| 1.5 m | EXIL-1500 |
| 2.0 m | EXIL-2000 |
| 3.0 m | EXIL-3000 |
Cable
| ITEM | PART # |
| Signal Cable | EL380004 |
End Anchors
| ITEM | PART # |
| Groutable Anchor | EXIL11000 |
| Groutable Anchor with Spring Legs | EXIL12000 |
| Hydraulic Borros Anchors (Double Acting) | EXIL13500 |
| Hydraulic Bladder Anchor (Please confirm Borehole diameter) |
EXIL14000 |
Top
| ITEM | PART# |
| Anchor kit for mounting top sensor at surface (optional) |
EXA0379 |
Ordering Info Considerations
| Sensor range |
| Extension: compression ratio (10%, 25%, 50%, 75%, 90% – as standard) |
| Number of anchors, type and depths |
| Cable length |
| Accessories & optional equipment |
| Borehole diameter & orientation |
| Environmental considerations |
| Drilling method & soil/rock types |
| Other environmental considerations |
Accessories & Optional Equipment
| ITEM | PART# |
| Grout and/or bleed tubes | Contact RST |
| Vibrating Wire Readout | VW2106 |
| Dataloggers | Contact RST |
| Hydraulic Pump for Borros & Bladder Anchors | EXHYDPUMP |
| 1/8 in. Inflation Line for Hydraulic Bladder Anchors | BP0545 |
| 3/16 in. Inflation Line for Borros Anchors | BP0557 |
| 1/8 in. Tube Union | B-200-6 |
| 1/8 in. Ferrule Set | B-200-SET |
| 3/16 in. Tube Union | B-300-6 |
| 3/16 in. Ferrule Set | B-300-SET |
File Name
Multi-Point Inline Extensometer Installation Manual
Resource Type
Manual| Language | Version | Download |
|---|---|---|
| English | EXM0097I |
|
Speak with an Expert
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