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Measurements of selective Pore Pressure Transducers (PPTs) have been validated in element tests. These sensors were originally designed for model tests to investigate two-phase flow in a porous medium. By separately measuring pressures in each phase (wetting and non-wetting) of two immiscible phase liquids in sand, capillary pressure can be obtained in model tests under 1 - or N-g conditions. A calibration was carried out by imposing stationary DNAPL head pressures. The relationship between capillary pressure and water saturations “Pc-S” of a two-phase fluid/sand system was determined using the selective PPTs mounted in direct contact with the soil model. For comparison, the classical method consisting of pressure a measurements outside the soil model, with fluid contact only, was also applied to obtain the Pc-S relationship. The resulting Pc-S curves of the classical method were compared to those of the selective PPTs. These results validate the new measuring technique. Practical experiences on the use of the selective PPTs in model tests are also discussed.

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