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Jack Out Earth Pressure Cell
RST Jack Out Earth Pressure Cells are used to
measure active and passive pressures on diaphragm walls. The cell itself is constructed of two
circular, stainless steel plates welded around their
periphery. The space between the two plates is
filled with an incompressible fluid. A transducer is
connected to this space and measures the pressure exerted on the incompressible fluid. This cell
is connected to a backing plate, which is connected
to a double acting hydraulic jack and an opposite
reaction plate that is the same diameter as the cell.
When the hydraulic jack is expanded it acts on the
backing plate so that the cell is not damaged. The
backing plate is also attached to the hydraulic jack
by a swivel joint allowing for some misalignment in
placement of the jack out pressure cell.
This complete unit is installed in the reinforcing
cage that is to be placed in the slurry filled trench.
After the reinforcement cage is lowered into the
trench the hydraulic jack is expanded, forcing the
earth pressure cell and reaction plate against the
sides of the trench. The hydraulic jack is kept pressurized until the concrete has set.
RST Jack Out Earth Pressure Cells can be combined with an integral piezometer to allow effective
stress readings to be made. Cells are available in
10.2 cm (4 in.), 22.9 cm (9 in.), and 30.5 cm (12 in.)
sizes (overall size: 4½, 9½, 12½). Others sizes are
available as special orders, please consult RST.
Offical RST distributor in
Europe & MENA
Geotechnical Centre
Rougham Industrial Estate
Rougham, Bury St Edmunds
Suffolk IP30 9ND
ENGLAND
Telephone: +44(0)1359 271167
Facsimile: +44(0)1359 271168
Geosense is a division of
Marton Geotechnical Services Ltd
info@mgsgeosense.co.uk
www.mgsgeosense.co.uk
I S O 9 0 0 1: 2 0 0 0
R E G I S T E R E D Q U A L I T Y SYS T E M
applications
Measurement and control
of contact pressures on
diaphragm walls.
Verifying design assumptions,
assuring soil pressures are not
larger than those the structure
was designed to withstand.
features
Choice of pneumatic,
strain gauge, or vibrating wire
pressure transducers.
High accuracy and sensitivity.
Suitable for remote monitoring
and datalogging.
Cell is designed to have a
stiffness similar to that of
typical soils.
Field rugged, easy to install,
easy to operate.
LPB0006D
Fluid pressure calibrated.
Jack Out Earth Pressure Cell
specifications
ITEM
MODEL: JOPC-P
MODEL: JOPC-S
MODEL: JOPC-V
Transducer Type
Pneumatic
Strain Gauge*
Vibrating Wire
Range
up to 2000 psi/13800 kPa
up to 5000 psi/34500 kPa
up to 5000 psi/34500 kPa
Overrange
2000 psi maximum
200-500% F.S.dependent on sensor
200% F.S.
Accuracy
.25 or .1% F.S.
to ±0.1% F.S. dependent on sensor
to 0.1% F.S.
Resolution
Equal to readout instrument
Infinite
0.1% F.S. minimum
Thermal Effect on Transducer Zero
Nil
0.1 % per °C from 0-50 °C
0.1 % F.S. per °C
Excitation Voltage
N/A
dependent on sensor
5 V sq. Wave
Signal Output
N/A
0-100 mV
0-1 V
0-5 V
4-20 mA
1200-2000 Hz
Conductor
2 X 3/16 O.D. pneumatic tubes
4x#20
2x#20
2x#20
4x#20 with thermistor
Operating Temperature
-40° to +105°F
-40° to +40°C
-40° to +250°F
-40° to +120°C
-20° to +150°F
-29° to +65°C
Active Cell Diameter
10.2, 22.9 or 30.5 cm
(4 in., 9 in. or 12 in.)
10.2, 22.9 or 30.5 cm
(4 in., 9 in. or 12 in.)
10.2, 22.9 or 30.5 cm
(4 in., 9 in. or 12 in.)
Overall Cell Diameter
11, 24 or 32 cm
(4 1/2 in., 9 1/2 in. or 12 1/2 in.)
11, 24 or 32 cm
(4 1/2 in., 9 1/2 in. or 12 1/2 in.)
11, 24 or 32 cm
(4 1/2 in., 9 1/2 in. or 12 1/2 in.)
Hydraulic Jack Size
depends on trench width
(many sizes available)
depends on trench width
(many sizes available)
depends on trench width
(many sizes available)
Reaction Plate Diameter
same as chosen cell size
same as chosen cell size
same as chosen cell size
*Various types of strain gauge transducers are available, as preferred.
REINFORCEMENT
CAGE
SLURRY
TRENCH
ordering info
When ordering, please specify your trench width, accuracy requirements and pressure range.
JACKOUT PRESSURE CELL SENSOR TYPE AND SIZE
PART #
Pneumatic - 12 in. diameter
LPJOPC-P(12)
Pneumatic - 9 in. diameter
LPJOPC-P(9)
Pneumatic - 4 in. diameter
LPJOPC-P(4)
Strain Gauge - 12 in. diameter
LPJOPC-S(12)
Strain Gauge - 9 in. diameter
LPJOPC-S(9)
Strain Gauge - 4 in. diameter
LPJOPC-S(4)
Vibrating Wire - 12 in. diameter
LPJOPC-V(12)
Vibrating Wire - 9 in. diameter
LPJOPC-V(9)
Vibrating Wire - 4 in. diameter
LPJOPC-V(4)
TOTAL PRESSURE CELL,
HYDRAULIC JACK,
BACKING & REACTION PLATES
Typical installation of a Jack Out Earth Pressure Cell.
www.mgsgeosense.co.uk
info@mgsgeosense.co.uk
RST Instruments Ltd. reserves the right to change specifications without notice. LPB0006D