Modeling the Stress-Dilatancy Relationship of Unsaturated Silica Sand in Triaxial Compression Tests
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 142, Issue 11
Abstract
It is well known that partial saturation increases the shear strength and dilatancy of unsaturated sand. However, little research has been carried out on the actual stress-dilatancy relationship. This paper shows that the increase in peak shear strength caused by partial saturation is consistent with an increase in dilatancy, and that conventional stress-dilatancy theories are still valid for unsaturated sand. The use of state indexes as a proxy for dilatancy were investigated and extended to unsaturated sands. Additionally, these indexes can be used to establish a critical state line that is based on material properties only. The validity of the stress-dilatancy theories and the use of state indexes offer simplicity in modeling the shear behavior of unsaturated sand. This will be demonstrated in this paper with the Nor-Sand model, with which the wetting collapse can be explained as a consequence of a loss of dilatancy characteristics.
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Acknowledgments
The authors would like to thank Dr Takashi Sakanoue from Tokyo Gas, Japan, for his technical and financial support. This project has received funding from the European Union’s Seventh Framework Program for research, technological development and demonstration under grant agreement no PIAP-GA-2012-324522 and from the Swiss National Science Foundation under grant agreement P1SKP2 158621.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 142 • Issue 11 • November 2016
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© 2016 American Society of Civil Engineers.
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Received: Nov 29, 2015
Accepted: Mar 22, 2016
Published online: Jun 13, 2016
Published in print: Nov 1, 2016
Discussion open until: Nov 13, 2016
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