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Compression behaviour of natural and reconstituted clays / Z.-S. Hong in Géotechnique, Vol. 62 N° 4 (Avril 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 4 (Avril 2012) . - pp. 291–301 Titre : Compression behaviour of natural and reconstituted clays Type de document : texte imprimé Auteurs : Z.-S. Hong, Auteur ; L.-L. Zeng, Auteur ; Y.-J. Cui, Auteur Année de publication : 2012 Article en page(s) : pp. 291–301 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Clays  Compressibility  Laboratory  tests Résumé : The intercept of the l o g ( 1 + e ) – l o g σ ′ v straight line is introduced to describe the effect of the starting point on the compressibility of natural and reconstituted clays. It is found that when the effective stress exceeds the remoulded yield stress, the compression behaviour of reconstituted clays is controlled solely by the water content at the remoulded yield stress and the liquid limit. Comparison of the compression behaviour of natural and reconstituted clays indicates that their difference in compressibility is caused by soil structure and the difference in water content at the compression starting point. The compression behaviour of natural clays can be classified into three regimes: (a) the pre-yield regime, characterised by small compressibility, with soil structure restraining the deformation up to the consolidation yield stress; (b) the transitional regime, characterised by a gradual loss of soil structure when the effective stress is between the consolidation yield stress and the transitional stress; and (c) the post-transitional regime, characterised by the same change law in compression behaviour as reconstituted clays when the effective stress is higher than the transitional stress. For the investigated clays, the transitional stress is 1·0–3·5 times the consolidation yield stress. The compression index varies solely with the void ratio at an effective stress of 1·0 kPa for both natural clays in the post-transitional regime and reconstituted clays when the effective stress exceeds the remoulded yield stress, and when compressed in such cases the compression curves of both natural clays and reconstituted clays can be well normalised to a unique line using the void index. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/issue/geot/62/4# [article] Compression behaviour of natural and reconstituted clays [texte imprimé] / Z.-S. Hong, Auteur ; L.-L. Zeng, Auteur ; Y.-J. Cui, Auteur . - 2012 . - pp. 291–301. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 4 (Avril 2012) . - pp. 291–301 Mots-clés : Clays  Compressibility  Laboratory  tests Résumé : The intercept of the l o g ( 1 + e ) – l o g σ ′ v straight line is introduced to describe the effect of the starting point on the compressibility of natural and reconstituted clays. It is found that when the effective stress exceeds the remoulded yield stress, the compression behaviour of reconstituted clays is controlled solely by the water content at the remoulded yield stress and the liquid limit. Comparison of the compression behaviour of natural and reconstituted clays indicates that their difference in compressibility is caused by soil structure and the difference in water content at the compression starting point. The compression behaviour of natural clays can be classified into three regimes: (a) the pre-yield regime, characterised by small compressibility, with soil structure restraining the deformation up to the consolidation yield stress; (b) the transitional regime, characterised by a gradual loss of soil structure when the effective stress is between the consolidation yield stress and the transitional stress; and (c) the post-transitional regime, characterised by the same change law in compression behaviour as reconstituted clays when the effective stress is higher than the transitional stress. For the investigated clays, the transitional stress is 1·0–3·5 times the consolidation yield stress. The compression index varies solely with the void ratio at an effective stress of 1·0 kPa for both natural clays in the post-transitional regime and reconstituted clays when the effective stress exceeds the remoulded yield stress, and when compressed in such cases the compression curves of both natural clays and reconstituted clays can be well normalised to a unique line using the void index. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/issue/geot/62/4#

Compression behaviour of reconstituted soils at high initial water contents / Z.-S. Hong in Géotechnique, Vol. 60 N° 9 (Septembre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 9 (Septembre 2010) . - pp. 691-700 Titre : Compression behaviour of reconstituted soils at high initial water contents Type de document : texte imprimé Auteurs : Z.-S. Hong, Auteur ; J. Yin, Auteur ; Y.-J. Cui, Auteur Année de publication : 2011 Article en page(s) : pp. 691-700 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  equipment  Compressibility  Clays  Suction  pressure  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Oedometer tests starting from a very small effective vertical stress of 0·5 kPa were performed on three reconstituted clays with different liquid limits. The soils were prepared at various initial water contents, ranging from 0·7 to 2·0 times their corresponding liquid limits. It is observed that the e–log σ ′ v compression curves show an inverse ‘S' shape due to suction pressure resisting deformation, similar to that of soft natural clays caused by consolidation yield stress. The suction pressure σ ′ s of the reconstituted clays can be correlated with the ratio of initial void ratio to void ratio at liquid limit e 0/e L. The suction pressure curve defined by a unique relationship between suction pressure σ ′ s and the normalised void ratio at suction pressure e s/e L is also proposed to distinguish between the pre-suction and the post-suction states. In addition, Burland's concept of the intrinsic compression line is adopted for correlating the compression curves of various reconstituted clays at high initial water contents. It has been found that the void index is a powerful parameter for normalising the compression curves in the post-suction state. Nevertheless, it seems that Burland's intrinsic compression line slightly underestimates the void index at the low stresses considered in this study. An extended intrinsic compression line is then derived in order to better fit the data for stresses lower than 25 kPa. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.09.p.059 [article] Compression behaviour of reconstituted soils at high initial water contents [texte imprimé] / Z.-S. Hong, Auteur ; J. Yin, Auteur ; Y.-J. Cui, Auteur . - 2011 . - pp. 691-700. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 9 (Septembre 2010) . - pp. 691-700 Mots-clés : Laboratory  equipment  Compressibility  Clays  Suction  pressure  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Oedometer tests starting from a very small effective vertical stress of 0·5 kPa were performed on three reconstituted clays with different liquid limits. The soils were prepared at various initial water contents, ranging from 0·7 to 2·0 times their corresponding liquid limits. It is observed that the e–log σ ′ v compression curves show an inverse ‘S' shape due to suction pressure resisting deformation, similar to that of soft natural clays caused by consolidation yield stress. The suction pressure σ ′ s of the reconstituted clays can be correlated with the ratio of initial void ratio to void ratio at liquid limit e 0/e L. The suction pressure curve defined by a unique relationship between suction pressure σ ′ s and the normalised void ratio at suction pressure e s/e L is also proposed to distinguish between the pre-suction and the post-suction states. In addition, Burland's concept of the intrinsic compression line is adopted for correlating the compression curves of various reconstituted clays at high initial water contents. It has been found that the void index is a powerful parameter for normalising the compression curves in the post-suction state. Nevertheless, it seems that Burland's intrinsic compression line slightly underestimates the void index at the low stresses considered in this study. An extended intrinsic compression line is then derived in order to better fit the data for stresses lower than 25 kPa. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.09.p.059