Role Of a Vibrating Wire Peizometer In Projects

Vibrating wire piezometer is a highly useful device designed to measure soil pore pressure. The device has a vibrating transducer and signal cable driven by wire pressure. It is used by either installing it in a borehole or embedding in a fill or suspending in a standpipe. A portable readout provides the readings which are very accurate and error-free when done rightly. A data logger can also be used for the purpose.

The instrument responds amazingly well to changes in pore pressure and can be used in all typed of soils. The measurement is obtained in terms of frequency and hence can be sent over long cable lengths automatically. To ensure that the instrument works efficiently and in an error-free manner, it must be sheltered from electrical transients.

Vibratingwire piezometer is generally used in the following applications:

·         Determining safe rates of fill or excavation

·         To find out slope stability

·         To know the effects of dewatering systems used in excavations

·         In earth-fill dams and embankments to track performance

·         To check containment systems at landfills and tailings dams.

 Installing the vibrating wire piezometer is easy and can be done quickly. Three methods are commonly used:

·         Grout-in method

·         Sand filter method

·         Push-in method

The vibrating wire piezometer works by converting water pressure to a frequency signal through a diaphragm. 

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Applications of Vibrating Wire Piezometer

A VibratingWire Piezometer measures water level for excavation walls, checks slope stability, measures pore pressure in embankments and soft ground, checks and monitors flow and leak of underground water in dams and banks.

The instrument comes with a high tensile steel wire that is attached to a diaphragm in contact with water pressure at one end and a fixed anchor on the other end. The wire is plucked electrically with resonant frequency of vibration at a proportion to tension in the wire.  This frequency leads to an alternate current in a coil that can be converted to a pressure.  The vibration of wire is detected and recorded to a readout device. The frequency output is not disturbed by the external electrical noise and can tolerate wet wiring that is common in all geotechnical applications.

MEMSPortable tilt meter is applied to monitor the tilt or changes in an inclination of a structure. It monitors rotation of retaining walls, warns of any likely structural damage, monitors landslide, bridges piers, observes compression in earth dams and embankments.  The tilt meter is fixed to the structure that has to be monitored with an angle bracket welded to steel into concrete or rock. Readings are obtained with a data logger or portable readout.

The Strata MonitoringInstruments manufacturer must keep pace with the changes and innovation being experienced in the study of instrumentation and civil engineering. The manufacture has to ensure safety, high accuracy and proper maintenance of the instruments. 

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Uses of Vibrating Wire Crackmeter in Concrete Structures

Monitoring and measuring of movements across surface cracks and joints in concrete structures or rock is done by the Vibrating Wire crackmeter. Monitoring applications include   brick and stone buildings, bridges and dams, construction joints, pipelines and joints in concrete and rocks. Made of high quality steel, the sensor provides accurate and reliable readings for long term monitoring.  

It is fully waterproof and is ideal for both manual and remote monitoring. The sensor is fitted across a joint or crack and keeps a track of any movements by detecting changes in tension in the vibrating wire.  It is connected with a thermistor to monitor the temperature.

Deformation of rock or soil masses is detected by the convergence meter.  The device detects and measures contraction or elongation between two fixed anchor points that are set up in the mass. Connecting rods from one anchor leads to the transducer assembly that is placed at the second anchor point. The transducer records the changes in distance between the two anchors.

Three way movements at block joints and cracks are monitored by the vibrating wire triaxial joint meter. It has a 3D mounting system that comprises of two arms and two groutable anchors and three displaceable transducers to monitor the temperature. The instrument is waterproof and is suitable for both manual and remote monitoring. It gives robust and accurate readings and comes with a over-voltage surge arrestor for protection against electrical damage.

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Examine Strain Movements with Vibrating Wire Strain Gauge

Instruments used to check the short and long term strains on tunnel linings, arches, piles, struts, dams, rock surfaces and many other such structures are called vibrating wire strain gauge. The device comes with a tensioned steel wire enclosed in a stainless steel tube. The steel wire is supported by two blocks at the two ends.  Electromagnetic coils located close to the wire when excited induce the wire to swerve at high speed.

The wire sways for a certain time creating an alternate current output. The frequency in the output is detected and fixed by a readout unit supported by a vibrating wire interface converting it into units of strain. The two blocks change their position due to the changes in the tension of the wire within the gauge. This results in change in resonant frequency of swerving of the wire. The device comes in different types to suit various applications like embedment type, surface mount, sister bar and spot weld type.

Conversion of fluid pressures in standpipes, boreholes, embankments, pipelines and pressure vessels are done by vibrating wire piezometers.  It is used for understanding the nature of the site, predict slope stability, check the safe rate for placing the fill and evaluate effectiveness of drainage schemes. These instruments are available in different models to suit various needs.

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