1 Application
Model VWD-A Vibrating Wire Soil Settle Gauge is applied to measure the settlement and displacement of soil, stone dams, stile slope, base foundations and structures. At the same time the temperature value of the settle point can be measured. The Vibrating Wire Crackmeter has the intelligent identification function.
2 Technical Specifications
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VWD-100A
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VWD-150A
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VWD-200A
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VWD-250A
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Measurement Range (mm)
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0 ~ 100
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0 ~ 150
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0 ~ 200
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0 ~ 250
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Sensitivity (mm/F)
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??0.05
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??0.08
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??0.1
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??0.125
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Accuracy (F.S)
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??0.1%
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??0.1%
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??0.1%
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??0.1%
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Temperature Range (??)
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-40 ~ +80
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-40 ~ +80
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-40 ~ +80
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-40 ~ +80
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Temperature Accuracy (??)
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??0.5
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??0.5
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??0.5
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??0.5
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Gauge Lengths (m)
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1 ~ 50
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1 ~ 50
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1 ~ 50
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1 ~ 50
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Size of Settlement Plate (mm)
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300??300
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300??300
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300??300
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300??300
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Water Pressure Resistance (MPa)
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??1
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??1
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??1
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??1
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Insulation Resistance (M??)
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??50
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??50
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??50
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??50
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Remark: Frequency Modulus F= Hz2??10-3
3Theory of Operation
3.1 Constitution
Model VWD-A Vibrating Wire Soil Settle Gauge consists of settlement plate, displacement transducer, settlement inner cover tube, settlement inner cover tube, multi-direction joint, measurement rod, joint of measurement rod, protecting tube, joint of measurement rod, centralizing ring, anchor and cables.
3.2 Mechanism
After the soil settlement gauge is installed, the anchor is fixed positioned and connected with the front rod through the measurement rod. Besides, the back end of the gauge is connected and fixed with the settlement plate. When there is settlement displacement on the measured soil body, the settlement plate and the displacement transducer will be synchronously displaced. Thus, this displacement variation is transferred to the vibrating wire via the rod in order to generate the strain variation. Thereby, the oscillating frequency of the vibrating wire is changed as the consequence. The electromagnetic coils stimulate the vibrating wire and measure the oscillating frequency. As the result, the frequency signal is transmitted via the cable to the readout device and the displacement value of the measured soil body is thereby obtained. Meanwhile, the temperature value of the settled point can also be measured.
3.3 Calculation
The deformation value L has a linear relationship with the output frequency modulus ??F as the meter is bearing the axial deformation under a consistent environmental temperature:
L= k??F=k(F?CF0)
where,
k: Sensitivity with the unit of mm/F;
??F: Difference between the measured value and the reference one with the unit of F;
F: Measured value with the unit of F;
F0: Reference value with the unit of F.
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