Abstract
Language | English |
---|---|
Pages | 581-594 |
Journal | Géotechnique |
Volume | 60 |
Issue number | 8 |
DOIs | |
Publication status | Published - 1 Jul 2010 |
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Keywords
- anisotropy
- clays
- compaction
- earth fill
- laboratory tests
- stress path
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Mechanical behaviour of unsaturated kaolin (with isotropic and anisotropic stress history). Part 1: wetting and compression behaviour. / Sivakumar, V; Sivakumar, R; Murray, E J; Mackinnon, P; Boyd, JL.
In: Géotechnique, Vol. 60, No. 8, 01.07.2010, p. 581-594.Research output: Contribution to journal › Article
TY - JOUR
T1 - Mechanical behaviour of unsaturated kaolin (with isotropic and anisotropic stress history). Part 1: wetting and compression behaviour
AU - Sivakumar, V
AU - Sivakumar, R
AU - Murray, E J
AU - Mackinnon, P
AU - Boyd, JL
PY - 2010/7/1
Y1 - 2010/7/1
N2 - Over the last 40 years considerable progress has been made in understanding the complex behaviour of unsaturated soils. Research using constitutive modelling has extended the critical state framework and the concept of yielding in saturated soils to encompass unsaturated soils experiencing suction. However, validation testing of the framework for unsaturated soils has shown disagreement with the basic propositions. The main reason for this disparity is the anisotropic properties of the soil specimens tested as a result of preparation using one-dimensional compaction. The paper describes the detailed testing carried out to justify this statement. As part of the work presented, samples of unsaturated kaolin were prepared using isotropic compression. The suctions in these samples were reduced to predefined values by wetting under low isotropic loading. The pore size distributions, the pressure–volume relationships and yielding under subsequent isotropic loading are compared with tests on samples prepared by statically compressing kaolin into a one-dimensional compaction mould. The anisotropically compressed samples had initial water contents and specific volumes similar to those of the isotropically prepared samples and were also tested under reducing suctions; they exhibited distinctly different behaviour when tested under similar conditions. The results obtained from the isotropically prepared and tested samples have shown, probably for the first time, the existence of a unique normal compression surface that is not dependent on the initial conditions of the samples. The shape of the loading–collapse (LC) yield locus is shown to be different from the generally accepted form.
AB - Over the last 40 years considerable progress has been made in understanding the complex behaviour of unsaturated soils. Research using constitutive modelling has extended the critical state framework and the concept of yielding in saturated soils to encompass unsaturated soils experiencing suction. However, validation testing of the framework for unsaturated soils has shown disagreement with the basic propositions. The main reason for this disparity is the anisotropic properties of the soil specimens tested as a result of preparation using one-dimensional compaction. The paper describes the detailed testing carried out to justify this statement. As part of the work presented, samples of unsaturated kaolin were prepared using isotropic compression. The suctions in these samples were reduced to predefined values by wetting under low isotropic loading. The pore size distributions, the pressure–volume relationships and yielding under subsequent isotropic loading are compared with tests on samples prepared by statically compressing kaolin into a one-dimensional compaction mould. The anisotropically compressed samples had initial water contents and specific volumes similar to those of the isotropically prepared samples and were also tested under reducing suctions; they exhibited distinctly different behaviour when tested under similar conditions. The results obtained from the isotropically prepared and tested samples have shown, probably for the first time, the existence of a unique normal compression surface that is not dependent on the initial conditions of the samples. The shape of the loading–collapse (LC) yield locus is shown to be different from the generally accepted form.
KW - anisotropy
KW - clays
KW - compaction
KW - earth fill
KW - laboratory tests
KW - stress path
U2 - 10.1680/geot.8.P.007
DO - 10.1680/geot.8.P.007
M3 - Article
VL - 60
SP - 581
EP - 594
JO - Géotechnique
T2 - Géotechnique
JF - Géotechnique
SN - 0016-8505
IS - 8
ER -