On the development of an Ultra-High Capacity Tensiometer capable of measuring water tensions to 7 MPa

J. Mendes, D. Gallipoli, A. Tarantino, D. Toll

Research output: Contribution to journalArticle

Abstract

Tensiometers are increasingly used in geotechnical engineering to monitor pore-water tension in the field and to study the hydro-mechanical behaviour of unsaturated soils in the laboratory. Early tensiometers exhibited a relatively small measuring range, typically limited to a tension of 0.1 MPa, due to water tension breakdown inside the sensing unit at absolute negative pressures. This limitation was subsequently overcome by the design of High Capacity Tensiometers (HCT), which enabled the measurement of considerably larger pore-water tensions. According to literature, the highest value of water tension ever recorded by a HCT is equal to 2.6 MPa. In the present work, this value is almost tripled by designing a novel Ultra-High Capacity Tensiometer (UHCT) capable of recording water tensions up to 7.3 MPa. This is achieved by replacing the traditional ceramic interface with a nanoporous glass (typically employed by physicists for the study of confined liquids), which has never been used before for the manufacture of tensiometers. The maximum attainable tension has been determined via tests where the UHCT measurement was progressively increased by vaporising water from the glass interface until the occurrence of tension breakdown (often referred to as "heterogeneous cavitation" or "tensiometer cavitation"). The increased measuring range and the potentially larger measuring stability of the proposed UHCT will contribute to enhance laboratory testing of soils at high suctions and long-term monitoring of earth structures.
LanguageEnglish
Number of pages26
JournalGéotechnique
Early online date27 Jun 2018
DOIs
StateE-pub ahead of print - 27 Jun 2018

Fingerprint

tensiometer
Water
Cavitation
water
cavitation
Soils
Glass
Geotechnical engineering
porewater
glass
Vaporization
measuring
Earth structure
Earth (planet)
geotechnical engineering
ceramics
suction
Monitoring
Liquids
Testing

Keywords

  • water tension measurement
  • tensiometer
  • capillary pressure
  • suction
  • unsaturated soils

Cite this

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abstract = "Tensiometers are increasingly used in geotechnical engineering to monitor pore-water tension in the field and to study the hydro-mechanical behaviour of unsaturated soils in the laboratory. Early tensiometers exhibited a relatively small measuring range, typically limited to a tension of 0.1 MPa, due to water tension breakdown inside the sensing unit at absolute negative pressures. This limitation was subsequently overcome by the design of High Capacity Tensiometers (HCT), which enabled the measurement of considerably larger pore-water tensions. According to literature, the highest value of water tension ever recorded by a HCT is equal to 2.6 MPa. In the present work, this value is almost tripled by designing a novel Ultra-High Capacity Tensiometer (UHCT) capable of recording water tensions up to 7.3 MPa. This is achieved by replacing the traditional ceramic interface with a nanoporous glass (typically employed by physicists for the study of confined liquids), which has never been used before for the manufacture of tensiometers. The maximum attainable tension has been determined via tests where the UHCT measurement was progressively increased by vaporising water from the glass interface until the occurrence of tension breakdown (often referred to as {"}heterogeneous cavitation{"} or {"}tensiometer cavitation{"}). The increased measuring range and the potentially larger measuring stability of the proposed UHCT will contribute to enhance laboratory testing of soils at high suctions and long-term monitoring of earth structures.",
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On the development of an Ultra-High Capacity Tensiometer capable of measuring water tensions to 7 MPa. / Mendes, J.; Gallipoli, D.; Tarantino, A.; Toll, D.

In: Géotechnique, 27.06.2018.

Research output: Contribution to journalArticle

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