Accuracy Of Determining Pre-Consolidation Pressure From Laboratory Tests

Abouzar Sadrekarimi

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: SOIL AND TERRAIN CHARACTERIZATION - I Geotechnical Laboratory Testing

ABSTRACT: Shear strength and compressibility of fine-grained soils is strongly influenced by its stress history and the maximum (pre-consolidation) pressure (p). Accurate determination of p is thus critical for settlement and stability analysis involving fine-grained soils. A series of 30 laboratory oedometer tests is carried out in this study based on controlled-rate of strain and incrementally-loaded testing techniques. Several Canadian clay specimens are subject to cycles of one-dimensional compression loading and unloading in order to produce a known stress history and p. The imposed p are compared with the predictions of 11 methods for determining p. The accuracies of these methods are subsequently evaluated by comparing their predictions with p imposed during the consolidation experiments. While these methods mostly overestimate p, it is determined that a graphical approach based on the slopes of the virgin compression and recompression segments of soil consolidation curve provides the most accurate predictions of p. The potential ranges of errors associated with the application of each method are also presented. These would provide an opportunity to recognize the possible magnitude of uncertainty in a geotechnical analysis or design as a result of estimating 'p from laboratory tests.

RÉSUMÉ: La résistance au cisaillement et de la compressibilité des sols à grains fins est fortement influencée par son histoire des contraintes et la pression maximale. La détermination exacte de la pression de préconsolidation est donc essentiel pour le règlement et l'analyse de stabilité impliquant des sols à grains fins. Une série de 30 essais oedométriques en laboratoire est effectué dans cette étude basée sur la vitesse de déformation contrôlée et les techniques d'essai à chargement de manière incrémentielle. Plusieurs spécimens d'argile canadienne sont soumis à des cycles de compression unidimensionnelle le chargement et le déchargement afin de produire une histoire de stress connues et pré-pression de consolidation. Les pressions de consolidation préalable imposé sont comparés avec les prédictions de 11 Méthodes de détermination de la pression de consolidation préalable. La précision de ces méthodes sont ensuite évalués en comparant ses prédictions avec pré-pressions de consolidation imposées pendant la consolidation des expériences. Alors que ces méthodes surestiment généralement pré-pression de consolidation, il est déterminé qu'une approche graphique basé sur les pentes de la vierge la compression et de la recompression entraînent des segments de la courbe de consolidation du sol fournit des prédictions les plus précises possibles de pré-pression de consolidation.

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Cite this article:
Abouzar Sadrekarimi (2016) Accuracy Of Determining Pre-Consolidation Pressure From Laboratory Tests in GEO2016. Ottawa, Ontario: Canadian Geotechnical Society.

@article{3453_0710133532,author = Abouzar Sadrekarimi,title = Accuracy Of Determining Pre-Consolidation Pressure From Laboratory Tests,year = 2016}