Vibrating Wire Pressure Cells measure total stresses in soils and is a combination of effective stress and pore-water pressures. They are normally used to validate design assumptions and to give adequate warning of soil pressures in excess of those designed to be exerted by a structure.
The Vibrating Wire Pressure Cell is used to measure total pressure, particularly in earth or rockfill structures.
The cells are normally used to validate design assumptions and to give adequate warning of soil pressures in excess of those which a structure is designed to withstand.
The VW Pressure Cell has two designs; the double face design is formed from a circular flat cell comprising two flexible plates of Stainless Steel welded together around their periphery, providing two active faces, the single face design has one thick metal plate and one flexing plate, providing one active face.
A narrow gap is formed between the plates and is filled with highly de-aired hydraulic oil, a Vibrating Wire pressure transducer is connected to the cell by a short length of steel tubing forming a closed hydraulic system.
- Uses proven Vibrating Wire technology
- Accurate, reliable and robust
- Low, medium and high pressure ranges available
- Low volume change and slender profile
- Single and double active faces available
- Various ranges of size and pressure available
- Suitable for manual or remote monitoring
- Over 30 years of expertise in the design and manufacture of Vibrating Wire instrument technology
- Accurate, repeatable readings over long cable lengths
- Long working life with long-term stability
- Arching and stress concentrations minimised
- Over-voltage surge arrestor protects against electrical damage
- Design prevents case stresses from affecting readings
Pressure Cells Operation
Both cell and transducer are embedded in the medium to be monitored with an armoured cable that connects the instrument to a terminal unit, portable readout unit or data logger. Any external pressure on the cell causes the steel plates to compress creating a change in pressure in the oil within the cell.
The change in pressure is converted by the VW transducer into an electrical signal and may be remotely read using a VW readout or data logger.
The readout or data logger can display either frequency based units or, by inputting the instrument calibration factors, engineering based units.
The double faced cell measures the pressure from two directions while the single faced cell will only measure the pressure acting on its thinner plate.
Vibrating Wire Pressure Cells are installed within fills to determine the distribution, magnitude and directions of total pressure.
They can also be installed with one surface against a structure to measure total pressure acting on retaining walls, or against piles, pipes and slurry trench walls.
Typical applications include:
- Concrete, Embankment and Tailings Dams
- Diaphragm or Sheet Pile Wall
- Retaining Wall