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DEFORMATION MEASUREMENTS WITH INCLINOMETERS (1988)
Inclinometers have steadily gained widespread use for measuring deformations In landslides, natural slope creep, temporary excavations, earth and rock embankments, slurry walls, shafts, tunnels, lateral pile movements, and settlements beneath tanks, fills, and foundations. Inclinometer data can be used to determine displacement magnitude and rate and the location of the zone of displacement, as well as the absolute p!)Sition of the inclinometer casing In the ground. High-precision Inclinometers today utlllze servo-accelerometer sensors In a unlaxlal or biaxial configuration, mounted Inside a waterproof wheel carriage. The most common Is the traversing borehole type, where the wheels are oriented and guided by specially made grooved casing. Fixed-In-place inclinometers employ the same guide casing but are used infrequently due to high cost. Inclinometer monitoring Is one of the most labor- and data-Intensive geotechnlcal measuring activities. In addition to straightforward data reduction, many errors have to be Identified and dealt with before results can be presented and correctly Interpreted. In the authors' experience, many Inclinometer monitoring programs have failed to yield good results because errors were not recognized. In this paper, guidance Is given to the reader regarding Inclinometer system design, Installation, monitoring, data processing, and sources of errors and their resolution. Accuracy of the Inclinometer Is highly dependent on the equipment selected, the method by which it Is installed in the ground, monitoring techniques, correct scrutiny of the data, and ability to correct instrument errors. A servoaccelerometer-type system Is capable of a precision of ±0.05 to 0.25 in. over 100 ft when the casing Is vertical or horizontal. The best results are achieved when cooperation and understanding between engineers, clients, and contractors provide continuity in the total monitoring process.
TRANSPORTATION RESEARCH RECORD 1169