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Static Pore Pressure Meters

The subsoil is an accumulation of multiple layers of different types of soil. Every soil type has its own unique properties resulting in stable and instable soils and individual permeability characteristics. This causes the ground water pore pressure to vary per area and depth.

Electrical pore pressure meter is an absolute-pressure transducer designed to measure fluid pressure and therefore an excellent tool to observe the in-situ ground water pore pressure in soil and rock masses during a certain period of time. These meters are mainly used to monitor engineering works in dykes, sand-bodies for road-construction, embankments, land fills, natural slopes, hydraulic structures, foundations, retaining walls, dams, excavations, tunnels, waste repository sites, and alike. They are always put in place for longer periods. It is therefore that we supply both single use pore pressure meters as well as retrievable pore pressure meters for relative short projects.

Because of their design, the pore pressure meters are easy to install using either a hand auger drill, drill rig or penetrometer pusher. The watertight, rigid housing made either of PVC or stainless steel protects the sensor components from the effects of water, mechanical shocks and external loads. A filter prevents solid material from entering while ensuring hydraulic continuity between groundwater and the sensor. Furthermore the meters do not require any maintenance; this makes them very suitable for long time projects and even permanent installations.

The pore pressure meters feature high accuracy and are compensated for temperature variations making the thermal-zero shift correction negligible. The latter is the result of the fact that the full scale calibration data are subdivided in 100 steps and stored in the internal memory module of the meter. These calibration values are used during the test to compensate the output values automatically. The pore pressure meters are immune mechanical stress and the high insulating resistance makes them very suitable for even the harshest environment. The voltage type output signals are easy to process.

  • Measurement of the influence of dynamic loads on the subsoil by trains or traffic
  • Determination of macro-stability mechanisms of soils
  • Determination of the degree of de-watering of soils
  • Assessment of the stability of an embankment and to ascertain if it is possible to add the next charge of fill material
  • Determination of the position of the freatic water table and the changes in the course of time (influenced either by tide, river discharge or drainage)
  • Determination of the degree of consolidation of the ground
  • Monitoring the variations in pore pressures in and near potential failing surfaces effected by plastic deformations
  • The detection of the beginning of (more superficial) slides
  • Determination of the influence of static loads on the pore pressure
  • Determination of the effectiveness of the installed infiltration system
  • Observation of the homogenity of occuring groundwater flow as a result of infiltration
  • Determination of the boundary conditions for groundwater flow analysis

The reading of the data can either be done by a person going into the field with a handheld read-out unit, or it can be done automatically using a remote data recorder with built-in GPRS-modem.

Using a remote data recorder enables you to monitor online the pore pressure meters in real time. Pore pressure data are recorded at preset intervals and stored until downloaded. In this way a practically continuous image of the variations in pore pressure is obtained.

The remote data recorders come in 2 versions:

  1. Version 1 ( 02 03 100) that assures for continuous registration, processing, recording and transmitting (GPRS) of data
  2. Version 2 ( 02 03 200) that only records and transmits data at preset intervals

Depending on the specific application of the pore pressure meters, it could be necessary to compensate for the barometric pressure. Gouda-Geo supplies purposely designed electronic barometers that can be connected to the dataloggers as well.

  • Measuring range: 0 – 500 kPa or 0 – 1000 kPa
  • Maximum pressure: 1000 kPa
  • Supply voltage: 8 – 32 Vdc
  • Output signal: 4 – 20 mA / 0 – 10 Vdc
  • Response time: < 5 ms (0 – 99%)
  • Insulation resistance: > 10 MΩ at 300 Vdc
  • EMC compatibility: EN 61000-6-3, 2007
  • Temperature range: 0 – 50 °C (compensated), -20 – 80 °C (storage)
  • Cable: PUR exterior with teflon core insulation can be ordered at any length (max. 25 m)
  • Red core: +Vdc
  • Black core: earth
  • White core: signal (0 – 10 Vdc output)
  • Housing: PVC or stainless steel 316 / 303
  • Weight: Approx. 120 gr.
  • Linearity (max. deviation of the optimum straight line): < 0.25 % of the full scale
  • Stability: < 0.1 % of the full scale
  • Temperature coefficient: < 0,01% / °C
  • Maximum inaccuracy: < 0,5 % (depends on the linearity, hysteresis, temperature coefficient, zero-shift and repeatability.
  • Static pore pressure meter, single use only, in PVC housing
  • Static pore pressure meter, single use only, in stainless steel housing
  • Static pore pressure meter, multiple use (retrievable type), in stainless steel housing