Bearing capacity of low plastic unsaturated soils using effective and total stress approaches

Won Taek Oh, Sai K. Vanapalli

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: Behaviour of Unsaturated Soils

ABSTRACT: Effective stress approach (ESA) originally proposed by Terzaghi (1943) for estimating the bearing capacity of saturated soils was modified by Vanapalli and Mohamed (2007) to estimate the variation of bearing capacity of unsaturated coarse-grained soils (Ip = 0%) with respect to matric suction. Total stress approach (TSA) proposed by Skempton (1948) was modified by Vanapalli et al. (2007) to estimate the variation of bearing capacity of unsaturated fine-p use the saturated shear strength properties and the Soil-Water Characteristic Curve along with fitting parameters. However, no parametric studies have been undertaken for the soils that have plasticity index values less than 8% (i.e. 0% < Ip < 8%). In the present study, the model footing test results obtained for a silty soil (Botkin silt, Ip = 6%) are analyzed using both the ESA and the TSA to check the validity of the proposed methods for unsaturated soils.

RÉSUMÉ: L'approche de la contrainte effective (ACE) d'abord proposée par Terzaghi (1943) pour estimer la capacité portante des sols a été élargie par Vanapalli et Mohamed (2007) pour estimer la variation de la capacité de sols grossiers non-saturés (Ip = 0%) en fonction de la succion matricielle. L'approche de la contrainte totale (ACT) proposée par Skempton (1948) a été élargie par Vanapalli et al. (2007) pour estimer la variation de la capacité portante de sols fins (8% Ip 60%) en fonction de la succion matricielle. Les approches proposées pour l'estimation de la capacité portante de sols non-saturés utilisent les propriétés de résistance au cisaillement du sol sous des conditions saturées et la courbe de rétention d'eau avec des paramètres d'ajustement. Cependant, aucune étude paramétrique n'a été entreprise pour les sols ayant un indice de plasticité de moins de 8% ( c.-à-d. 0% < Ip < 8%). Dans la présente étude, les résultats d'essais sur des semelles à échelle réduite obtenus pour un sol limoneux (Botkin silt, Ip = 6%) sont analysés en utilisant aussi bien la méthode ACE que ACT afin de vérifier la validité des méthodes proposées pour des sol non-saturés.

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Cite this article:
Won Taek Oh; Sai K. Vanapalli (2011) Bearing capacity of low plastic unsaturated soils using effective and total stress approaches in GEO2011. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GEO11Paper229,author = Won Taek Oh; Sai K. Vanapalli ,title = Bearing capacity of low plastic unsaturated soils using effective and total stress approaches,year = 2011}