SOME INITIAL EXPERIMENTAL FINDINGS ON THE INFLUENCE OF MODE OF SHEAR ON THE MONOTONIC SHEAR RESPONSE OF RECONSTITUTED SILTS

Daniel Barnes, Priyesh Verma, Dharma Wijewickreme

In the proceedings of: GeoQuébec 2015: 68th Canadian Geotechnical Conference & 7th Canadian Permafrost Conference

Session: Laboratory Testing I / Essais en laboratoire I

ABSTRACT: An experimental research program has been undertaken to investigate the influence of mode of shear on the monotonic shear response of relatively low plastic reconstituted silt obtained from a soil deposit located in Kamloops, British Columbia, Canada. The consolidated monotonic shear response of the reconstituted silt under undrained triaxial compression, undrained triaxial extension, and constant volume direct simple shear loading conditions were compared. In the triaxial tests, the silt specimens were reconstituted from an initial slurry state and then consolidated to three target effective confining stress levels. At all confining stress levels, the undrained shear strength observed under triaxial compression was observed to be approximately 20% greater than that noted from triaxial extension tests. The undrained shear strength measured from the direct simple shear loading at an effective confining stress level of 100kPa was observed to be similar to that measured in the triaxial extension test. This limited test data suggests similar trends to what has been observed for Ko - consolidated low plastic soft clays.

RÉSUMÉ: Un programme de recherche expérimental a été entrepris pour évaluer l'influence du mode de cisaillement sur la réponse en cisaillement statique du silt reconstitué à plasticité relativement faible, obtenu à partir d'un dépôt de sol à Kamloops, en Colombie Britannique, au Canada. Les réponses de cisaillement statique du silt reconstitué sous compression triaxiale non-drainée, extension triaxiale, et sous charge de cisaillement simple directe à volume constant, ont été comparées. Pour les tests triaxiaux, les échantillons de silt ont été reconstitués à partir d'un état initial boueux, puis consolidés vers trois niveaux de contraintes effectives de confinement ciblées. Pour tous les niveaux de contraintes de confinement, la force de cisaillement sous compression triaxiale a été maintenue à approximativement 20% de plus que celle des tests d'extension triaxiale. La force de cisaillement non-drainée mesurée à partir de la charge de cisaillement simple directe à un niveau de contrainte effective de confinement de 100 kPa correspond à celle mesurée sous tests triaxiaux. Ces données de tests limités suggèrent des tendances similaires à ce qui a été observé pour le Ko consolidé à faible plasticité.

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