The mechanical behaviour of an unsaturated compacted silty clay

Jotisankasa, Apiniti; Coop, M. R.; Ridley, Andrew

doi:10.1680/geot.2007.00060

Cited by 84 publications

(84 citation statements)

References 23 publications

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“…This is consistent with experimental observations (e.g. [34,45,50,51,59,63]). Figure 2 shows the retention response of a wetting path conducted with the initial state on the WR yield surface, but with three different initial positions of the M surface (i.e.…”

Section: Yielding On the Mechanical Yield Surface Alonesupporting

confidence: 93%

“…This is consistent with a number of experimental studies on retention behaviour available in the literature. In particular, Jotisankasa [34] and Jotisankasa et al [35] observed a similar response when investigating various drying paths on a compacted silty clay for three different as-compacted states. On drying, the two tests subjected to lower compaction stresses converged first (i.e.…”

Section: Simulations Of Air-drying Tests On Oc Samplesmentioning

confidence: 63%

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From saturated to unsaturated conditions and vice versa

et al. 2017

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Representing transitions between saturated and unsaturated conditions, during drying, wetting and loading paths, is a necessary step for a consistent unification between saturated and unsaturated soil mechanics. Transitions from saturated to unsaturated conditions during drying will occur at a nonzero air-entry value of suction, whereas transitions from unsaturated to saturated conditions during wetting or loading will occur at a lower nonzero air-exclusion value of suction. Air-entry and airexclusion values of suction for a given soil will differ (representing hysteresis in the retention behaviour) and both are affected by changes in the dry density of the soil or by the occurrence of plastic volumetric strains. The paper demonstrates, through model simulations and comparison with experimental data from the literature (covering drying, wetting and loading tests), that the Glasgow Coupled Model (GCM), a coupled elasto-plastic constitutive model covering both mechanical and retention behaviour, represents transitions between unsaturated and saturated behaviour in a consistent fashion. Key aspects of the GCM are the use of Bishop's stress tensor for mechanical behaviour, the additional influence of degree of saturation on mechanical yielding, inclusion of hysteresis in the retention behaviour, and the role of plastic volumetric strains (and not total volumetric strains) in the description of the water retention response. The success of the GCM in representing consistently transitions between saturated and unsaturated conditions, together with subsequent mechanical and retention responses, demonstrates the potential of this coupled constitutive model for numerical modelling of boundary value problems involving saturated and unsaturated conditions.

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Section: Yielding On the Mechanical Yield Surface Alonesupporting

confidence: 93%

Section: Simulations Of Air-drying Tests On Oc Samplesmentioning

confidence: 63%

From saturated to unsaturated conditions and vice versa

et al. 2017

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“…The higher activity of the clay probably explains the enhanced sensitivity of microporosity to suction changes. The variation of engineering properties of a given soil when compacted at different dry densities and water contents has been often reported (Cox, 1978;Reséndiz, 1980;Lawton et al, 1989Lawton et al, , 1991Alonso et al, 1992;Benson et al, 1992;Fredlund & Rahardjo, 1993;Tinjum et al, 1997;Vanapalli et al, 1999;Simms & Yanful, 2002;Santucci de Magistris & Tatsuoka, 2004;Jotisankasa et al, 2007Jotisankasa et al, , 2009. However, it is not feasible to isolate microstructural effects in many of these contributions, mainly because compacting dry or wet of optimum implies not only a different microstructure, but also a different suction.…”

Section: Microstructure and Compacted Soil Behaviourmentioning

confidence: 99%

Compacted soil behaviour: initial state, structure and constitutive modelling

Alonso¹,

Pinyol²,

Gens³

2013

Géotechnique

183

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The paper explores the behaviour of compacted soils throughout the (dry density-water content) compaction plane by means of a conceptual framework that incorporates microstructural information. The engineering properties of compacted soils are described by an initial state in terms of a yielding stress, soil suction and a microstructural state variable. Microstructure is defined by the ratio of microvoid volume to total void volume. The pattern of variation of the microstructural parameter within the compaction plane has been determined, for some compacted soils, by analysing mercury intrusion porosimetry data. The microstructure of wet and dry compaction conditions can then be quantified. To ensure consistency, the framework is cast in the form of a constitutive model defined in terms of an effective suction and a constitutive stress that incorporate the microstructural variable. The model is shown to be consistent with a number of experimental observations and, in particular, it explains the intrinsic collapse potential of compacted soils. It predicts, for a common initial suction, a higher collapse potential for dry of optimum conditions than for wet compaction. It also predicts in a natural manner the observed evolution of soil compressibility during drained or undrained loading. Model capabilities are illustrated by application to a testing programme on statically compacted samples of low-plasticity silty clay. The compression behaviour of samples compacted wet and dry of optimum and the variation of collapse strains with confining stress have been successfully reproduced by the model.

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“…8%, indicating that, in order to obtain accurate measurement of suctions, the tensiometer should ideally be calibrated using a method that resembles conditions of use. Further possible evidence for this can be found in the study by Jotisankasa (2005). Given the authors' findings here, the calibration factor used later to check extrapolation to the negative pressure range was that obtained under 'isotropic' conditions.…”

Section: Calibration In the Positive Rangementioning

confidence: 72%

“…The procedure for placing the tensiometer in contact with the sample is similar to that described by Hight (1982) for sealing a piezometer probe on a sample's side during saturated triaxial tests, and has been used frequently since (e.g. Wong et al, 2001;Jotisankasa, 2005). This calibration method corresponds to a condition where the pressure applied to the transducer through the ceramic stone was equal to the back-pressure inside the sample, and different from the cell pressure applied externally to the tensiometer's body.…”

Section: Calibration In the Positive Rangementioning

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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The mechanical behaviour of an unsaturated compacted silty clay

Cited by 84 publications

References 23 publications

From saturated to unsaturated conditions and vice versa

From saturated to unsaturated conditions and vice versa

Compacted soil behaviour: initial state, structure and constitutive modelling

Calibrations of a high-suction tensiometer

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