Mechanisms of Small-Strain Shear-Modulus Anisotropy in Soils
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 134, Issue 10
Abstract
In this paper, experimental studies using a true triaxial apparatus and a bender element system, and numerical simulations based on the discrete element method (DEM) were used to investigate the stress- and fabric-induced shear-stiffness anisotropy in soils at small strains. Verified by experiments and DEM simulations, the shear modulus was found to be relatively independent of the out-of-plane stress component, which can be revealed by the indistinctive change in the contact normal distribution and the normal contact forces on that plane in the DEM simulations. Simulation and experimental results also demonstrated that the shear modulus is equally contributed by the two principal stress components on the associated shearing planes. Fabric-induced stiffness anisotropy, i.e., the highest or , can be explained by simulation findings in which more contact normals prefer to distribute along the horizontal direction. The experiments and simulations also reveal that the fabric-induced stiffness anisotropy increases with an increasing aspect ratio of the particles. The assumption of transversely isotropic fabric in soils is valid based on the DEM simulation results; however, this assumption is not completely supported by the experimental results.
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Acknowledgments
This research was supported by the Hong Kong Research Grants Council and Hong Kong University of Science and Technology. The writers would like to thank Professor X. S. Li for providing the Itasca software, and Dr. X. Li for giving valuable suggestions. The writers are also grateful to the reviewers for valuable comments.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 134 • Issue 10 • October 2008
Pages: 1516 - 1530
Copyright
© 2008 ASCE.
History
Received: Oct 3, 2007
Accepted: Feb 20, 2008
Published online: Oct 1, 2008
Published in print: Oct 2008
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