Coupling of hydraulic and mechanical behaviour in unsaturated compacted clay

Alessandro Tarantino, Sara Tombolato

Research output: Contribution to journalArticle

155 Citations (Scopus)

Abstract

An experimental study was carried out to investigate the shear strength of a compacted non-active clay (Speswhite kaolin). A total of 33 statically compacted specimens were prepared, at vertical stresses of 300, 600 and 1200 kPa and water contents ranging from 0·24 to 0·34. This made it possible to explore a broad range of initial compaction-induced conditions and hence to examine whether differences in water retention characteristics and shear strength are due to differences in initial compaction-induced state or are to be attributed to fundamentally different microfabrics. A shearbox was modified to allow the direct measurement of negative pore water pressure using Trento high-suction tensiometers. Tests were carried out at constant water content by monitoring suction changes. In these tests, it was possible to investigate the transition from unsaturated to saturated states. In the first stage of the test, the specimen was compressed at constant water content. The specimen was therefore wetted, in the sense that its degree of saturation increased. Compression data were then used to investigate the influence of void ratio on the main wetting curve. Shear data were used to put forward a critical state framework for unsaturated compacted clay. This is described by three equations linking shear stress, normal total stress, suction, void ratio and water ratio.
LanguageEnglish
Pages307 –317
Number of pages11
JournalGeotechnique
Volume55
Issue number4
DOIs
Publication statusPublished - 1 May 2005

Fingerprint

suction
Water content
Clay
void ratio
water content
Hydraulics
hydraulics
clay
Shear strength
shear strength
compaction
Compaction
Water
tensiometer
critical state
Kaolin
Data compression
kaolin
water retention
wetting

Keywords

  • clays
  • suction
  • fabric/structure of soils
  • partial saturation
  • shear strength

Cite this

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title = "Coupling of hydraulic and mechanical behaviour in unsaturated compacted clay",
abstract = "An experimental study was carried out to investigate the shear strength of a compacted non-active clay (Speswhite kaolin). A total of 33 statically compacted specimens were prepared, at vertical stresses of 300, 600 and 1200 kPa and water contents ranging from 0·24 to 0·34. This made it possible to explore a broad range of initial compaction-induced conditions and hence to examine whether differences in water retention characteristics and shear strength are due to differences in initial compaction-induced state or are to be attributed to fundamentally different microfabrics. A shearbox was modified to allow the direct measurement of negative pore water pressure using Trento high-suction tensiometers. Tests were carried out at constant water content by monitoring suction changes. In these tests, it was possible to investigate the transition from unsaturated to saturated states. In the first stage of the test, the specimen was compressed at constant water content. The specimen was therefore wetted, in the sense that its degree of saturation increased. Compression data were then used to investigate the influence of void ratio on the main wetting curve. Shear data were used to put forward a critical state framework for unsaturated compacted clay. This is described by three equations linking shear stress, normal total stress, suction, void ratio and water ratio.",
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Coupling of hydraulic and mechanical behaviour in unsaturated compacted clay. / Tarantino, Alessandro; Tombolato, Sara.

In: Geotechnique, Vol. 55, No. 4, 01.05.2005, p. 307 –317.

Research output: Contribution to journalArticle

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AB - An experimental study was carried out to investigate the shear strength of a compacted non-active clay (Speswhite kaolin). A total of 33 statically compacted specimens were prepared, at vertical stresses of 300, 600 and 1200 kPa and water contents ranging from 0·24 to 0·34. This made it possible to explore a broad range of initial compaction-induced conditions and hence to examine whether differences in water retention characteristics and shear strength are due to differences in initial compaction-induced state or are to be attributed to fundamentally different microfabrics. A shearbox was modified to allow the direct measurement of negative pore water pressure using Trento high-suction tensiometers. Tests were carried out at constant water content by monitoring suction changes. In these tests, it was possible to investigate the transition from unsaturated to saturated states. In the first stage of the test, the specimen was compressed at constant water content. The specimen was therefore wetted, in the sense that its degree of saturation increased. Compression data were then used to investigate the influence of void ratio on the main wetting curve. Shear data were used to put forward a critical state framework for unsaturated compacted clay. This is described by three equations linking shear stress, normal total stress, suction, void ratio and water ratio.

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