Application
The in-place inclinometer employs a fixed string of sensors that can be monitored continuously by a data logger. Typical applications for horizontal in-place inclinometers include:
- Monitoring of ground movements induced by tunnel construction and excavation.
- Monitoring of stabilization measures such as grouting and underpinning.
- Monitoring settlement under tanks, landfills, embankments, and dams.
Operation
The in-place Inclinometer system consists of inclinometer casing and a string of electrolytic inclinometer sensors. The inclinometer casing controls the orientation of the sensors. It is installed in a horizontal borehole, buried in a trench, or attached to a structure, with one set of grooves oriented vertically. The string of sensors is positioned within the casing.
The sensors measure the inclination of the casing (tilt from horizontal). Changes in the inclination readings indicate that the casing has been displaced by ground movement. The amount of displacement is calculated by finding the difference between the current inclination reading and the initial reading and then converting the result to a vertical distance.
In most in-place inclinometer applications, sensors are connected to a data acquisition system that continuously monitors movements and can trigger an alarm when it detects a change, or rate of change, that exceeds a preset value.
Advantages
High Resolution:
The ceramic EL sensor has a range of +/- 10 degrees and a resolution of 0.0024 degrees or 0.04 mm per meter when read with a CR10X. Increased resolution is possible with a higher resolution readout device.
Ideal for Critical Applications:
In-place inclinometers are easily connected to real-time data acquisition systems, on-site alarms, and automatic dialers.
Lower Cost:
EL IPI systems cost significantly less than comparable servo-accelerometer systems.
Wheels:
Wheeled sensors can be removed to allow verification checks with a traversing probe or when sensors are needed an a different site.
Rigid Gauge Tubing:
Inclinometer calculations require straight-line segments for sensor gauge lengths. Rigid tubing satisfies this requirement. Rigidg gauge tubing also provides reliable performance across abrupt changes at the shear zone.
Single Cable Installation: The multiplexed version of the EL IPI installs with just one cable. Although multiplexed sensors are more expensive, their higher cost is partially offset by easier installation and wiring, and savings on signal cable and external multiplexers.
