Operation
 A
settlement cell consists of a liquid reservoir, liquid-filled
tubing, and the settlement cell, which contains a pressure transducer.
One end of the tubing is connected to the settlement cell, which
is embedded in fill or installed in a borehole. The other end
of the tubing is connected to the reservoir, which is located
away from the construction area.
The transducer measures the pressure created by the column of
liquid in the tubing. As the transducer settles with the surrounding
ground, the height of the column is increased and the settlement
cell measures higher pressure. Settlement is calculated by converting
the change in pressure to millimeters or inches of liquid head.
Advantages
- The reservoir and readout station can be located away from
the construction area. The cell and tubing are buried and
do not interfere with construction activities.
- Vibrating wire cells can be automated. Tubing lengths of up
to 300 m (1000 feet) are permissible with VW cells.
- Pneumatic cells are less expensive and are a good choice in lightning-prone regions.
Limitations
- Temperature
changes in reservoirs and above-ground tubing can affect
the repeatability of readings.
- Non-vented VW cells require corrections for barometric pressure, so barometric pressure must be recorded.
- Vented VW cells automatically compensate for changes in barometric pressure, but desiccant chamber must be maintained.
- Pneumatic cells cannot be automated and tubing length should be less than 100m (300 ft). However, barometric compensation is not required, since this is done when the readout is zeroed.
For more information
Please download the datasheets and manuals
listed below. These can be viewed and printed with Adobe
Acrobat Reader.
VW Settlement
Cell Datasheet
Vented VW Settlement Cell Manual
Non-Vented VW Settlement Cell Manual
Pneumatic
Settlement Cell Datasheet
Pneumatic Settlement Cell Manual
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