Jackout Pressure Cell
Pressure Cells

Jackout Pressure Cell

VWJPC-4500 Jackout Pressure Cells are used to measure active and passive pressures on diaphragm walls during excavation. They are installed within the diaphragm wall cage to monitor pressure on the walls. Any build-up of excessive pressure can be detected in time for remedial measures to be carried out.

The Pressure 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.

The cell is mounted onto one end of a double acting hydraulic ram via a swivel joint and at the other end is a reaction plate the same diameter as the cell.

The ram and cell assembly is installed into the reinforcement cage with the cell and reaction plate positioned either side of the cage with the ram passing through the reinforcement. It is loosely supported in the cage by tie wires or a prefabricated cradle.

After the reinforcement cage is lowered into the trench the hydraulic jack is hydraulically pressurised forcing the earth pressure cell and reaction plate against the sides of the trench. The hydraulic pressure is increased to ensure good embedment into the trench wall. The ram pressure is maintained throughout the pouring and curing of the concrete.

A vibrating wire piezometer can also be incorporated to measure pore water pressure.