Geosense TPC-4000 Total Earth Pressure Cells

Geosense TPC-4000 series Total Earth Pressure cells are designed to measure total pressure (effective stress and pore water pressure) in soils and at the interface between structures and the wall of excavation.

They are constructed from two stainless steel plates welded around their periphery with the narrow gap between the plates filled with hydraulic fluid. External pressure on the outside surfaces of the cell squeezes the two plates together, creating an internal fluid pressure. A length of stainless steel tube connects the cell to a pressure transducer (VWDT-5000 or SGT-3000) which converts the fluid pressure into an electrical signal that can be directly read or transmitted to a data logging system.

Models 4000 and 4020 are designed to measure soil pressure within soils. Models 4010 and 4030 are designed to measure soil pressures on structures and are fitted with fixing lugs. They have an extra thick backplate on one side which is placed against the structure to avoid any warping of the cell. The other side has a thin plate welded to the backplate which provides sensitive measurement of soil pressures.

VWDT-5000 vibrating wire pressure transducers may be read by the VW-2106 or any vibrating wire readout device and may be readily data logged using Campbell Scientific data loggers, the Cautus Logger CL1, or any other data loggers with vibrating wire interface modules.

Vibrating wire sensors output a frequency signal and are therefore insensitive to resistance changes in connecting cables caused by contact resistance or leakage to ground. Cable may be readily and simply extended on site without special precautions. Gauges may be read up to 1000 meters away from their installed location without change in calibration.

Strain gauge pressure transducers can be read with a direct readout in MPa or 4-20mA output which can be data logged.