Introduction to Tiltmeters

Applications

Portable Tiltmeter
Fixed Tiltmeters

Tiltmeters are used to monitor changes in the tilt of a structure. Tilt changes may be caused construction activities, such as excavation, tunneling, and dewatering, that affect the ground that supports the structure. Changes in tilt may also result from loading of a structure, such as the loading of a dam during impoundment, the loading of a diaphram wall during excavation, or the loading of a bridge deck due to wind and traffic.

Typical applications for tiltmeters include:

• Monitoring stabilization measures, such as pressure grouting and underpinning.
• Monitoring structures for the effects of tunneling and excavating.
• Evaluating the performance of bridges, beams, and dams under load.
• Monitoring the stability of structures in landslide areas.
• Monitoring the deflection and deformation of retaining walls.
• Monitoring convergence and other movements in tunnels.
• Providing early warning of threatening deformations, allowing time for corrective action to be taken or, if necessary, for safe evacuation of the area.

Types of Tiltmeters

Portable Tiltmeter

The Digitilt tiltmeter is carried from tilt plate to tilt plate to obtain measurements.

Advantages: A single tiltmeter can be used to monitor any number of inexpensive tilt plates.

Limitations: No remote reading, cannot be automated, accuracy affected by placement of tiltmeter on tiltplate.

Fixed Tiltmeter

EL tiltmeters are fixed directly to the structure and left in place. They are offered in narrow-angle and wide-angle versions.

Advantages: Accurate, high-resolution measurements, can be read remotely, easily automated, easy to install, reusable, reasonable cost.

Limitations: Some applications require temperature corrections, although careful placement of the tiltmeter can minimize this need.

Deep-Water Tiltmeter

This EL tiltmeter is a high resolution, narrow-angle tiltmeter designed for underwater applications. It is fixed to the structure.

Advantages: High resolution measurements, remote reading, easily automated, waterproof to 3Mpa.

Limitations: Signal cable must be protected by waterproof conduit.

Beam Sensor

EL beam sensors are similar to EL tiltmeters, except that the tilt sensor is mounted on a rigid beam with a defined gauge length, typically 1 to 2 meters long. Each end of the beam is anchored to the structure.

Advantages: The rigid beam makes it easy to convert changes in tilt to millimeters of movement (settlement, heave, convergence, or lateral displacement). Also, beam sensors can be linked end-to-end to monitor differential movements and provide absolute displacement and settlement profiles.

Limitations: Some applications require temperature corrections, although careful placement can minimize his need.

Track Monitor

EL track monitoring sensors monitor settlement and twist in railway tracks. This is a specialized application for tilt sensors.