Experimental procedures and cavitation mechanisms in tensiometer measurements

Tarantino, Alessandro; Mongioví, L.

doi:10.1007/978-94-015-9775-3_1

Cited by 35 publications

(61 citation statements)

References 9 publications

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“…The discusser has saturated two Imperial College tensiometers following the procedure suggested by Ridley & Burland (1999), and using a large triaxial cell as a saturation chamber and a vacuum pump capable of a minimum absolute pressure of about 3 kPa. In spite of the poor vacuum applied, these two tensiometers later exhibited a satisfactory performance in terms of measurement precision (tensiometers pr3 and pr4 in Tarantino & Mongiovì, 2000, 2001 that is comparable to that of the best-saturated Trento tensiometers (precision of about AE3 kPa relative to the average measured value). The experience of the discusser is that saturation of the ceramic is achieved mainly through cycles of cavitation and subsequent pressurisation (Tarantino & Mongiovì, 2001;Tarantino, 2003).…”

Section: Discussionmentioning

confidence: 79%

“…In spite of the poor vacuum applied, these two tensiometers later exhibited a satisfactory performance in terms of measurement precision (tensiometers pr3 and pr4 in Tarantino & Mongiovì, 2000, 2001 that is comparable to that of the best-saturated Trento tensiometers (precision of about AE3 kPa relative to the average measured value). The experience of the discusser is that saturation of the ceramic is achieved mainly through cycles of cavitation and subsequent pressurisation (Tarantino & Mongiovì, 2001;Tarantino, 2003). An inadequate initial saturation simply increases the number of cycles necessary to obtain a satisfactory performance.…”

Section: Discussionmentioning

confidence: 92%

“…Tarantino & Mongiovì (2001) and Tarantino (2003) showed evidence that inadequate saturation might result in readings that appear reliable and stable although actually incorrect. The authors have demonstrated this in a very rigorous fashion, and have addressed perhaps the main problem in tensiometer measurement, which is how to discriminate a good measurement from a bad one.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Tensiometer saturation and the reliable measurement of soil suction

Take¹,

Bolton²

2004

Géotechnique

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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Tensiometer saturation and the reliable measurement of soil suction

Take¹,

Bolton²

2004

Géotechnique

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“…For geotechnical applications Burland (1993, 1999) constructed a tensiometer that measured ψ m down to −1.5 MPa, unfortunately the instrument worked for a few hours or less. This tensiometer, later studied by Guan and Fredlund (1997) and Tarantino and Mongiovì (2001), required a 24 h pre-hydration phase in a high pressure chamber, at 4.0 MPa, to dissolve air bubbles, and stopped working as soon as cavitation occurred. The tensiometer can only be used in the laboratory due to the elaborate preparation prior to use.…”

Section: Introductionmentioning

confidence: 99%

Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

Ploeg

Gooren

Bakker

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately −0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed polymer tensiometers (POTs) are able to directly measure soil matric potentials until the theoretical wilting point (−1.6 MPa). By minimizing the volume of polymer solution inside the POT while maximizing the ceramic area in contact with that polymer solution, response times drop to acceptable ranges for laboratory and field conditions. Contact with the soil is drastically improved with the use of coneshaped solid ceramics instead of flat ceramics. The comparison between measured potentials by polymer tensiometers and indirectly obtained potentials with time domain reflectometry highlights the risk of using the latter method at low water contents. By combining POT and time domain reflectometry readings in situ moisture retention curves can be measured over the range permitted by the measurement range of both POT and time domain reflectometry.

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“…Recent studies have focused on the former, particularly aspects of the preconditioning procedure employed for saturation, such as the magnitude and duration of the positive pre-pressurisation stage and the effect of initial flooding of the tensiometer under vacuum (e.g. Tarantino & Mongiovi, 2001;Take & Bolton, 2003). Calibration has received less attention, however, with only one dedicated study by Tarantino & Mongiovi (2003) to our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Calibrations of a high-suction tensiometer

Lourenço¹,

Gallipoli²,

Toll³

et al. 2008

Géotechnique

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Citation for published item:vouren oD F hF xF nd qllipoliD hF nd ollD hF qF nd eugrdeD gF iF nd ivnsD pF hF nd wederoD qF wF @PHHVA 9glirtions of high sution tensiometerF9D q¡ eotehniqueFD SV @VAF ppF TSWETTVF Further information on publisher's website: httpXGGdxFdoiForgGIHFITVHGgeotFPHHVFSVFVFTSW Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. , et al. (2008). Géotechnique 58, No. 8, 659-668 [doi: 10.1680/geot.2008 659Calibrations of a high-suction tensiometerHigh-suction tensiometers are able to measure suctions up to 2 MPa. Direct calibration at such high suctions requires the imposition of negative water pressures, which are difficult to achieve using facilities commonly available in soil mechanics laboratories. For this reason, tensiometers are usually calibrated in the positive pressure range, and such calibration is subsequently extrapolated to negative pressures. This paper examines different experimental techniques to assess the accuracy of such extrapolation. Any error in the calibration process would be directly reflected in the measured values of suction, and might be particularly significant (in relative terms) for the measurement of low suctions. In addition, the results of this study show that calibration in the positive range is affected both by the physical configuration of the tensiometer during calibration and by aspects of its design. The paper concludes that linear extrapolation of the calibration from the positive to the negative range is sufficiently accurate provided that calibration is done under conditions that closely match the conditions in which the tensiometer will be used. Owing to structural differences between tensiometers, and also to suctioninduced 'calibration hysteresis', at least one check on the accuracy of the extrapolated calibration equation over a range of negative pressure should be performed, even if at low values of suction.

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Experimental procedures and cavitation mechanisms in tensiometer measurements

Cited by 35 publications

References 9 publications

Tensiometer saturation and the reliable measurement of soil suction

Tensiometer saturation and the reliable measurement of soil suction

Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

Calibrations of a high-suction tensiometer

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