Abstract: This paper presents the research results of undisturbed marine soft soil samples from Zhoushan areas. The index properties of the marine soils from the sampling areas are reviewed. The dynamic properties of these marine soil samples retrieved from different depths are tested by the resonant column method under various confining pressures. The resultant shear modulus and damping ratios with relation to the various magnitudes of dynamic shear strains (1x10^-6 ~1x10^-2) are obtained. The results indicate that, within the variation range of dynamic shear strains between 1x10^-6 and 1x10^-2, the sampling depth has minimal influence on the dynamic shear modulus and dynamic damping ratio; with the increase of dynamic shear strain, the dynamic shear modulus decreases and the damping ratio increases; the confining pressure has an obvious effect on both the ratio of dynamic shear modulus G/Gmax and the damping ratio D/Dmax, that is, the large the confining pressure is, the higher value of G/Gmax and the smaller of D/Dmax. The normalized dynamic shear modulus ratio and the damping ratio with related to the dynamic shear strain are obtained based on the theoretical analysis with the modified HardinDrevich model. These values are compared with the code recommended values as well as the values recommended by Yuan. These test results provide a better understanding of the dynamic properties of the Zhoushan marine soils.

Key words: Marine Soft Soils, Resonant Column Test, Dynamic Shear Modulus, Damping Ratio, Normalized Relationship