V1.1
MEMS Digital Portable Horizontal Inclinometer
09/02/2022
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2.3. The Measurement of Inclination
To generate a profile of an installed inclinometer casing, a series of interconnected
readings are recorded. The probe is orientated so that the fixed wheel is facing
downwards and inserted into the casing with the sprung upper wheels in the
corresponding upper groove. It is lowered to the far end of the casing and
suspended on one of the metallic cable markings.
At the far end of the casing, with the probe suspended (not resting on the bottom), a
reading is recorded. The probe is then lifted up by the distance equivalent to its
‘gauge length’ (see sketch) and another reading is taken. This process is repeated
up the full length of the casing.
To minimise the issue of ‘Human Error’, Geosense® has introduced the option of
‘Automatic Inclinometer Data Acquisition’ into its proprietary software. This utilises
the stability and accuracy of the sensors together with the intelligence of the ASD to
allow the software to determine when the readings are considered stable, record
them, instruct the user to move to the next reading elevation and sense when this
has been carried out.
Essentially, the user has only to respond to a series of audible prompts, thereby
almost removing the risk of errors caused by distraction, haste or miss-recording.
The uppermost wheel, denoted by the ‘A+’ on the probe, is the direction uppermost
wheel.
A ‘+’ change in the computed Displacement indicates a change in the inclination in
the ‘+’ direction.
In almost all cases, inclinometer surveys are conducted to record a profile from the
base of the inclinometer tube towards the top, even if the movements are to be
computed differently (from the ‘Top Down’). Commonly, monitoring assumes the
base of the tube is ‘beyond the zone of expected movements’, so movement data is
computed accordingly. There are some circumstances where this assumption does
not apply so movements are computed from the top downwards where the
movement of the top of the tube can be determined by other measuring systems.
Inclinometer surveys are almost NEVER conducted from the top towards the base.
Three surveys are normally conducted to establish the Base Data File (Initial Data).
The values are either averaged to generate the Base Data or a ‘Mean Data Set’ is
selected to represent the Base Data.
