Dynamic Properties of Gravelly Materials

Authors

1 Department of Civil Engineering,University of Tehran

2 Department of Civil Engineering,Iran University of Science and Technology

3 Department of Geomatics Engineering,Building and Housing Research Center

Abstract

This paper studies the dynamic characteristics (i.e. shear modulus and damping ratio)
of modeled gravelly soils used as construction materials in some rock-fill dams in Iran by conducting
large-scale triaxial testing. Tested specimens were compacted to more than 95% maximum dry density,
according to Modi ed Proctor, and tested according to ASTM D 3999. Accurate monitoring of strains by
means of non-contact type displacement transducers to infinitesimal strains as small as 0.0001% enabled
us to obtain Gmax with some extrapolation. Based on the available experimental results the ranges for
G=Gmax ????
and D ????
are defined for materials with > 30% fine content and materials with < 15%
fine content. The results clearly indicate the need for modification in previously proposed G=Gmax ????

curves, particularly for gravels with > 30% fine content. Also, the suggested D ????
curves lay out of
the bounds of data reported by previous researchers, which may be due to the effects of testing frequency,
fine content, and confining pressure. In addition, a predictive hyperbolic model for estimating normalized
shear modulus (G=Gmax) versus shear strain (
) is presented. Effects of the number of cyclic loadings
over the shear modulus and damping ratio are also investigated.

Keywords

Scientia Iranica
Volume 17, Issue 4 - Serial Number 4
Transactions on Civil Engineering (A)
July 2010

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