Test results revealed that shear modulus decreases with fines, and increases with relative density and confining pressure. Normalized shear modulus is not affected by fines, relative density and confining pressure, while damping ratio is affected by fines and confining pressure. Finally, field cyclic resistance ratios versus normalized shear wave velocity values are developed on the basis of cyclic triaxial and resonant column tests. | JSEE Vol. 19, No. 4, 2017 Dynamic Properties of Firoozkooh Sand-Silt Mixtures Ali Shafiee1, Rouzbeh Dabiri 2*, and Faradjollah Askari 3 1. Assistant Professor, California State Polytechnic University, Pomona 2. Assistant Professor, Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran, * Corresponding Author; email: rouzbeh_dabiri@ 2. Associate Professor, Geotechnical Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran Received: 10/06/2016 Accepted: 07/11/2017 AB S T RA CT Keywords: Firoozkooh sand; Non-plastic silt; Shear modulus; Damping ratio; Cyclic resistance; Shear wave velocity A series of undrained resonant column, monotonic and cyclic triaxial tests was performed to investigate the effects of non-plastic fines on the dynamic properties of Firoozkooh sand. Specimens of sand-silt mixtures were prepared at different densities, and tested under various confining pressures. Test results revealed that shear modulus decreases with fines, and increases with relative density and confining pressure. Normalized shear modulus is not affected by fines, relative density and confining pressure, while damping ratio is affected by fines and confining pressure. Finally, field cyclic resistance ratios versus normalized shear wave velocity values are developed on the basis of cyclic triaxial and resonant column tests. 1. Introduction Determination of dynamic deformation properties (., shear modulus and damping ratio) of soil materials is an important step in characterization of their dynamic behavior. Although empirical relationships for the dynamic properties of sands [1-3] have been developed well, these relationships for sand-non-plastic silt mixtures, if found, are rare. It is customary to use modulus reduction and damping curves of granular soils for sand-nonplastic silt mixtures. Hence, similar to sands and gravels, normalized modulus and damping .
