Inclinometers – Delivering great value to engineers

Have you heard the term 'inclinometer'? It's an instrument used for monitoring angular tilt. Sometimes inclinometers are also known as tile meter or tile sensor. As they are used for sensing movement, they are primarily installed in massive structures where they play a crucial role in ensuring safety throughout their life. They are generally used in concrete structures, dams, buried down a tunnel or sometimes for reading movements of volcanoes. The best thing about this instrument is that it produces most accurate results even at most irregular surfaces. These instruments are in use for more than half a decade.

The inclinometers used in earlier years were made of two basic components, one of which is a flat side, or base, on which it rests, and the second a hollow disc which is half filled with some heavy liquid. The glass face of the disc is surrounded by a graduated scale that marks the angle at which the surface of the liquid stands, with reference to the flat base. The line 0, lying parallel to the base, when the liquid stands on that line, the flat side becomes horizontal; the line 90, being perpendicular to the base, when the liquid stands on that line, the flat side is perpendicular or plumb. Intervening angles are marked, and, with the aid of conversion tables, the instrument indicates the rate of fall per set distance of horizontal measurement, and set distance of the sloping line.

Inclinometer instrument casing is generally placed in a near vertical borehole that traverses through expected zones of movement into stable ground. The digital inclinometer probe, control cable, pulley assembly, and readout are used to survey the casing. During a survey, the probe is taken upwards from the bottom of the casing to the top, rested in its travel at half-meter intervals for tilt measurements. The first survey establishes the initial profile of the casing. Further surveys display changes in the characteristics if ground movement occurs.

The inclination of the probe body is determined by two force-balanced servo-accelerometers. One accelerometer reads tilt in the plane of the inclinometer wheels, which track the longitudinal channels of the casing. The second accelerometer takes tilt in the plane vertical to the wheels. These inclination measurements are then converted to lateral deviations. The variations in lateral deviation are measured by comparing the data from current and basic surveys that display ground movements. Plotting the growing changes at each measurement interval delivers a high resolution displacement profile. Displacement profiles are beneficial for ascertaining the magnitude, depth, direction, and rate of ground movement. There are various advantages of inclinometers including assured performance, computerized calibrations, repeatable tracking, extended installation life and many more.