VW Piezometer
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Transcript of VW Piezometer
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GEO-Instruments
Vibrating Wire Piezomete
Applications Monitoring pore water
pressures to determine slopestability.
Monitoring the effects of
dewatering systems used forexcavations. Monitoring the effects of ground
improvement systems such asvertical drains and sand drains.
Monitoring pore pressures tocheck the performance of earthfill dams and embankments.
Monitoring pore pressures tocheck containment systems atland fills and tailings dams.
Principle of OperationThe VW piezometer convertswater pressure to a frequencysignal via a diaphragm, a
tensioned steel wire, and anelectromagnetic coil.
The piezometer is designed sothat a change in pressure on thediaphragm causes a change inthe tension of the wire. An electro-magnetic coil is used to excite thewire, which then vibrates at itsnatural frequency. The vibration ofthe wire in the proximity of the coilgenerates a frequency signal thatis transmitted to the readoutdevice.The readout or data logger storesthe reading in Hz. Calibrationfactors are then applied to thereading to arriveat a pressure in engineering units.
Installation Methods Grout-In:The piezometer is
lowered to the specified depthand the borehole is simplybackfilled with a bentonite-cement grout.
Sand Filter:The borehole isflushed with water orbiodegradable drilling mud. Asand filter is placed around thpiezometer at the specifieddepth. A bentonite plug is
formed at the top of the sandfilter. Then the remainder of tborehole is filled with abentonite-cement grout.
. Embankments:The
piezometer is embedded insand and then covered withhand-compacted select fill.Signal cables are routedthrough trenches and covered
with compacted fill. Bentonitewater stops are placed atappropriate locations.
Northeast Office
24 Celestial Drive, Suite BNarragansett RI, 02882Phone 800.477.2506Fax 401.633.6021
Northwest Office
2100 196th Street, Suite 109Lynnwood, WA 98036
Tel. 800-477-2506Fax. 206-299-9580
California Office
182 Howard Street, Suite 326San Francisco, CA 94105
Tel. 800-477-2506Fax. 415-704-3154
Mid-Atlantic Office
5765-F Burke Centre ParkwBurke, Virginia 22015
Tel. 800-477-2506 x260
We make it easy to get the data you need. www.geo-instruments.com [email protected]
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Features Groutable:The VW piezometer can be installed
without a sand filter or bentonite seal. Thisgreatly simplifies same-hole installation ofmultiple piezometers or piezometers withinclinometer casing.
High Resolution: VW Piezometers provide a
resolution of 0.025% of full scale.
High Accuracy: Geo-Instruments automated,precision calibration system ensures that VWPiezometers meet or exceed specifications.
Rapid Response: VW Piezometers respond vequickly to small changes in pore-water pressurewhether they are grouted in, pushed intocohesive soils, or embedded in a sand filter zon
Reliable Signal Transmission: With properlyshielded cable, signals from the VW piezomete
can be transmitted long distances.
GEO-INSTRUMENTS GEO Vibrating Wire Piezome
Sensor Type Pluck-type vibrating wire sensor with built-in thermistor
Range 50, 100 and other ranges on request
Resolution 0.025%FS
Accuracy 0.1% FS
Temperature Range -20 to +50C
Temperature Coefficient < 0.04% FS per C
Maximum Pressure 1.5 x rated range
Filter 50-micron sintered stainless steel
Weight 0.16 kg (0.3 lb)
Materials Stainless Steel
Dimension 0.75 x 7.75
Model Numbers GEO-VW-PZO-50 GEO-VW-PZO-100
Specifications
Northeast Office
24 Celestial Drive, Suite B
Narragansett RI, 02882Phone 800.477.2506Fax 401.633.6021
Northwest Office
2100 196th Street, Suite 109
Lynnwood, WA 98036Tel. 800-477-2506Fax. 206-299-9580
California Office
182 Howard Street, Suite 326
San Francisco, CA 94105Tel. 800-477-2506Fax. 415-704-3154
Mid-Atlantic Office
5765-F Burke Centre Parkw
Burke, Virginia 22015Tel. 800-477-2506 x260
We make it easy to get the data you need. www.geo-instruments.com [email protected]
