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E31.2 E32.2

Vibrating Wire Liquid Settlement System

Vibrating Wire Liquid Settlement System, Geosense, VWLSS-200The Geosense® VWLSS-200 Vibrating Wire Liquid Settlement System is used to monitor settlement or heave in soils and other structures such as embankments, earth and rockfill dams.

Working principle

The main components are a reservoir (single or multiple), liquid-filled tubing and a vibrating wire pressure transducer cell mounted on a plate or, for borehole application, attached to an anchor.

The vibrating wire sensor is attached to a settlement plate at the point of estimated settlement. The sensor is connected via two liquid-filled tubes which are connected to a reservoir located on stable ground. As the transducer settles with the surrounding ground the height of the column is increased and the corresponding higher pressure is measured by the transducer.
Settlements are calculated by converting the pressure to millimetres of liquid head.

Settlement Plate, VW Pressure SensorThe pressure sensor transducer uses a pressure sensitive diaphragm with a vibrating wire element attached to it which is mounted inside an evacuated and hermetically sealed housing. Various housings are available to suit application. The transducer operates on the principle that a tensioned wire, when plucked, vibrates at its resonant frequency. The square of this frequency is proportional to the strain in the wire. Fluid pressures acting on the diaphragm causes a deflection of the diaphragm which then changes the tension in the vibrating wire thus altering the resonant frequency of the wire.


Vented System: The pressure sensor is vented so that it is automatically compensated for changes in atmospheric pressure.

Sealed System: The pressure sensor is sealed and therefore independent atmospheric readings should be taken and compensations made accordingly.

VWLSS-200 vibrating wire settlement sensors may be read by the VW2106 or any vibrating wire readout device and may be readily data logged using Campbell Scientific or any other data loggers with vibrating wire interface modules. Vibrating wire transducers output a frequency signal, and are therefore insensitive to resistance changes in connecting cables caused by contact resistance or leakage to ground. Cable may be readily and simply extended on site without special precautions. Gauges may be read up to 1000 metres away from their installed location without change in calibration.

Features

  • Not affected by barometric pressure 
  • In-situ checks available 
  • Air can be easily removed 
  • Manual or automated readout 
  • Reservoir can be sited away from construction area

Applications

Subsurface point settlements/heave beneath:

  • Embankments 
  • Surcharges 
  • Fills 
  • Dams 
  • Landfills

Specifications

Standard Range

7, 17 metres

Sensor Accuracy

0.1% full scale
System Accuracy Site Dependent
Resolution 0.025% full scale
Temperature Range   -20oC to +80oC

Diagram of Installation 

Vibrating Wire Liquid Settlement System, Installation, Diagram

Model Description

 VWPS-201V    VW vented pressure sensor 70 kPa
 VWPS-202V  VW vented pressure sensor 140 kPa
 VWPS-203V   VW vented pressure sensor 175 kPa
 VWPS-204V   VW vented pressure sensor 345 kPa
 VWPS-201S   VW sealed pressure sensor 70 kPa
 VWPS-202S   VW sealed pressure sensor 140 kPa
 VWPS-203S   VW sealed pressure sensor 175 kPa
 VWPS-204S   VW sealed pressure sensor 345 kPa
 VWSR211R   1 cell reservoir
 VWSR212R   2 cell reservoir
 VWSR213R   3 cell reservoir
 VWSR214R   4 cell reservoir
 VWSR215R   5 cell reservoir
 VWSR216R   6 cell reservoir
 VWSR217R   7 cell reservoir
 VWSR218R   8 cell reservoir
 VWSR219R   9 cell reservoir
 VWSR220R   10 cell reservoir
 VWSP230  450 x 450 mm plate
 VWSP231   500 x 500 mm plate
 K10-045   6mm OD x 4 mm ID twin nylon tubing with PVC outer sheath - per metre 
 Q10-020   Type 900-1 cable - per metre

Ordering Information

  • Sensor Type
  • Sensor range
  • Plate size
  • Number of reservoirs
  • Tube length
  • Cable length

VIC:

Melbourne

This email address is being protected from spambots. You need JavaScript enabled to view it.

t (03) 9938 3830

f (03) 9938 3899

m 0428 315 502

NSW:

Sydney

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t (02) 9986 1857

m 0418 381 709

QLD:

Brisbane

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t (07) 3040 6166

m 0419 477 715

 

WA:

Perth (Head Office)

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t (08) 9322 4020

m 0408 034 668

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