Application
Typical applications include:
- Monitoring horizontal strain in embankment dams.
- Monitoring tension cracks in earth structures.
Operation
The soil strainmeter employs a potentiometer and a rod mounted between two anchors to monitor horizontal movements of the surrounding soil. These components are linked together so that movement of one anchor relative to the other causes a change in the output of the potentiometer. The initial reading of the strainmeter is used as a datum. Subsequent readings are compared to the datum to calculate the magnitude, rate, and acceleration of movement.
Strainmeters are usually installed in series along the axis of anticipated deformation. Strainmeters may also be arranged in arrays or in groups with different alignments. A gauge length of 3 to 6 meters is typical, but will vary according to the expected magnitude of movement and the type of structure being monitored.
The strainmeter is available in two versions. The double-sensor version is equipped with two potentiometers mounted back-to-back to provide cable savings. The single-sensor version is used with odd number series or when only one gauge length is required.
Advantages
Easy Installation: The strainmeter is designed for easy assembly, easy extension of gauge lengths, and easy adjustment.
Reduced Cable Costs: The double-sensor version provides cable economies since a single length of cable can serve two sensors and two gauge lengths.
Manual or Automatic Readout: Strainmeters can be read manually with a portable indicator or can be connected to a data logger for unattended readings.
