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Journal of Applied Mathematics
Volume 2013, Article ID 385278, 7 pages
Research Article

Micromechanical Formulation of the Yield Surface in the Plasticity of Granular Materials

1Universiti Kebangsaan Malaysia (UKM), 43600 Bandar Baru Bangi, Selangor, Malaysia
2Department of Geotechnical Engineering, Faculty of Civil Engineering, K. N. Toosi University of Technology, 1346 Vali Asr Street, Vanak, Tehran 19697, Iran

Received 7 June 2013; Revised 31 July 2013; Accepted 15 August 2013

Academic Editor: Pengcheng Fu

Copyright © 2013 Homayoun Shaverdi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An equation is proposed to unify the yield surface of granular materials by incorporating the fabric and its evolution. In microlevel analysis by employing a Fourier series that was developed to model fabric, it is directly included in the strength of granular materials. Inherent anisotropy is defined as a noncoaxiality between deposition angle and principal compressive stress. Stress-induced anisotropy is defined by the degree of anisotropy and the major direction of the contact normals. The difference between samples which have the same density (or void ratio) but different bedding angles is attributed to this equation. The validity of the formulation is verified by comparison with experimental data.