A review and analysis of granular shear experiments under low effective stress conditions
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The constitutive law for granular materials is governed mainly by the intergranular friction, which depends strongly on the gravitational force or effective isotropic stress. Such experiments are mostly performed with relatively high effective isotropic stress. This fact poses serious limitations on the formulation of a materially objective constitutive model based on experiments performed on earth. This paper analyzes the limited experimental data of shear strength and rheology of granular materials, subject to low effective stress conditions obtained in microgravity μg as well as in 1 g conditions. Results from these experiments show that granular materials may have an extremely high macroscopic peak friction angle and clear nonlinear S-shape non-Bingham fluidity in low effective stress conditions. In this paper, the classical limit equilibrium method is employed, and a rheological constitutive model is used to study experimental data. The limit equilibrium method enables the authors to correlate the bearing capacity of sand foundation with high peak friction angles under varying effective stress conditions. The calibrated analytical solution for the rheological constitutive model under low effective stress conditions, predicts a clear S-shape correlation of the viscous shear stress and shear strain rate. The mutation or inflection point takes place around the in-situ Niigata earthquake shear strain rate. The results of this paper are of great relevance to the assessment of seismic liquefaction hazards of infrastructure on earth.
KeywordsGranular material Low confining pressure Microgravity Shearing Rheology Liquefaction
This project is supported by the National Natural Science Foundation of China (Grant Nos. U1738120 and 11474326). The authors would like to thank Qilin Wu for his help on manuscript compiling.
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We certify that there is no actual or potential conflict of interest in relation to this article.
- 4.Towhata, I., Anh, T.T.L., Yamada, S., Motamed, R., obayashi, Y.: Zero-gravity triaxial shear tests on mechanical properties of liquefied sand and performance assessment of mitigations against large ground deformation. In: International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, Missouri University of Science and Technology, San Diego, California (2010).Google Scholar
- 21.Zhang, X.: Prandtl and Terzaghi bearing capacity formulas of a strip footing solved by slip—line method of plasticity. J. Tianjin Univ. 2, 92–100 (1987)Google Scholar
- 22.Terzaghi, K., Terzaghi, K.P., Ralph, B., Terzaghi, K.P., Ralph, B.: Theoretical Soil Mechanics. Wiley, Hoboken (1965)Google Scholar
- 23.Cheng, G.Y., Qiu, R., Duan, C.: Analytical formula of K. Terzaghi ultimate bearing capacity coefficient under totally coarse foundation base. J. Civ. Aviat. Univ. China. 29(1), 25–28 (2011)Google Scholar