Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

The paper reports on our effort to extend the well-known Hardin's equation by the influence of the grain size distribution curve. The study is motivated by the fact that Hardin's equation with its commonly used constants can significantly over-estimate the small strain shear modulus Gmax of well-graded sands. Approximately 350 resonant column (RC) tests with additional P-wave measurements have been performed on 33 specially mixed grain size distribution curves of a quartz sand with different mean grain sizes d50, coefficients of uniformity Cu = d60/d10 and fines contents FC. The experiments show that for constant values of void ratio and pressure, the shear modulus Gmax and the small-strain constrained elastic modulus Mmax are independent of the mean grain size, but strongly decrease with increasing coefficient of uniformity. A fines content further reduces the small-strain stiffness. In order to improve the estimation of Gmax and Mmax, the parameters of Hardin's equation have been correlated with Cu and FC. A correlation of Gmax and Mmax with relative density Dr is less accurate. For a certain shear strain amplitude γ, the modulus degradation factor G(γ)/Gmax is smaller for higher Cu-values but does not depend on the fines content. An extension of an empirical formula for the modulus degradation factor is presented.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

On the Influence of the Grain Size Distribution Curve on Dynamic Properties of Quartz Sand

San Diego, California

The paper reports on our effort to extend the well-known Hardin's equation by the influence of the grain size distribution curve. The study is motivated by the fact that Hardin's equation with its commonly used constants can significantly over-estimate the small strain shear modulus Gmax of well-graded sands. Approximately 350 resonant column (RC) tests with additional P-wave measurements have been performed on 33 specially mixed grain size distribution curves of a quartz sand with different mean grain sizes d50, coefficients of uniformity Cu = d60/d10 and fines contents FC. The experiments show that for constant values of void ratio and pressure, the shear modulus Gmax and the small-strain constrained elastic modulus Mmax are independent of the mean grain size, but strongly decrease with increasing coefficient of uniformity. A fines content further reduces the small-strain stiffness. In order to improve the estimation of Gmax and Mmax, the parameters of Hardin's equation have been correlated with Cu and FC. A correlation of Gmax and Mmax with relative density Dr is less accurate. For a certain shear strain amplitude γ, the modulus degradation factor G(γ)/Gmax is smaller for higher Cu-values but does not depend on the fines content. An extension of an empirical formula for the modulus degradation factor is presented.