Hydraulic Piezometer
The hydraulic piezometer system includes a piezometer tip, tubing
filled with a de-aired liquid, and a readout unit such as a manometer,
Bourdon pressure gauge, or a pressure transducer.
Pore-water pressure acts on the piezometer tip and the liquid-filled
tubes transmit the pressure to the readout device.
A low air-entry tip with 60-micron pores and a permeability of
3 x 10
-4
m/s is used in saturated soils. A high air-entry tip with
1-micron pores and a permeability of 3 x 10
-8
m/s is used in unsatu-
rated soils and where negative pore-pressures are anticipated.
The twin-tube configuration makes it possible to replace the de-aired
liquid, provides redundant readings (one from each tube), and
provides a way to measure soil permeability.
The fluid in the tubing must be de-aired. Air bubbles in the system
can create reading errors and slow response time. The system should
be flushed when the reading from one tube does not match the
reading from the other.
Advantages
q
Simple, reliable mechanism.
q
Good response time even in soils with low permeability.
q
Can be used in permeability tests.
q
Capable of reading negative pore-pressures.
q
Reading station is remote from work area and does not interfere
with construction activity.
Limitations
q
Must be de-aired periodically. De-airing process requires special
equipment and is time-consuming.
q
Cabinet or gauge house required for readout device and
de-airing equipment.
q
Elevation difference between readout or tubing and
piezometric level is limited to 5 meters.
q
Cannot be operated in freezing temperatures and can be damaged
by freezing.
Piezometers
3-13
Rembco Geotechnical Contractors specializes in
slope stabilization,
soil nail wall,
foundation repair
and support,
grouting,
shoring,
micropile
construction,
rock drilling, and we remediate
sinkholes. We use a
problem-solving approach in the geotechnical portions of buildings, bridges, water plants, sewage plants, tunnels,
installing caisson bottom, and roads. We are experienced in these applications:
micro piles,
sinkhole repair,
permeation and
pressure
grouting,
soil nails,
cement grouting,
chemical grouting,
micropiles,
compaction grouting, and
rock anchors.
Rembco techniques apply when adding new structures: especially
rock anchor,
microfine cement,
soil nailing, and
micropile
installations for foundation support. Our specialties are
soil nails,
rock anchor,
chemical and
compaction grouting,
mini piles,
sinkhole repair,
micropiles, and
soil nailing.
