Undrained brittleness of sand in triaxial compression and ring shear tests

Abouzar Sadrekarimi, Scott Olson

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Laboratory Testing

ABSTRACT: Undrained brittleness index, IB, is defined as the difference between the peak and critical undrained shear strengths normalized by the peak undrained strength, and indicates soil contractiveness and severity of strain softening. In this study, the results of 25 undrained triaxial compression and 20 constant volume ring shear tests performed on two clean sands and one silty sand are used to evaluate IB. The results illustrate that IB increases with initial void ratio and state parameter and is affected by particle shape and particle damage, but is independent of the mode of shear (triaxial compression and ring shear). In addition, IB appears uniquely related to the ratio of consolidation stress to effective stress at critical state, 'c/'cs, and critical strength ratio, su(critical)/'c, independent of sand type, mode of shear, initial fabric, and particle damage. These relationships suggest an upper bound critical strength ratio of about 0.3.

RÉSUMÉ: L™indice de fragilité non-drainé du sol, IB, est définie comme la différence entre les forces pics et les forces critiques de cisaillement non-drainé qui est normalisée par la résistance au pic non- drainé . Il indique le contractiveness et la gravité des adoucissement du sol. Dans cette étude, les résultats de25 essais de compression triaxiale non-drainée et 20 essais de cisaillement avec la sonnerie de volume constante sont utilisés pour évaluer l'IB. Les essais sont faits sur deux des sables propres et un sable limoneux . Les résultats montrent que l'IB augmente avec l™indice de vide initiale et paramètre d'état et sois influencé par la forme des particules de sable, et le dommage de particules et sois indépendant du mode de cisaillement (compression triaxiale et cisaillement annulaire). Par ailleurs, IB est uniquement lié au rapport decontrainte de consolidation de la contrainte effective à l'état critique, 'c/'cs, et le rapport de force critique, su(critical)/'c, et est indépendant du type de sable, le mode decisaillement , structure initiale, et le dommage des particules. Ces relations indiquent une limite supérieure ratio lié force critique d'environ 0.3.

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Cite this article:
Abouzar Sadrekarimi; Scott Olson (2011) Undrained brittleness of sand in triaxial compression and ring shear tests in GEO2011. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GEO11Paper138,author = Abouzar Sadrekarimi; Scott Olson ,title = Undrained brittleness of sand in triaxial compression and ring shear tests,year = 2011}