The study on dynamic shear modulus and damping ratio of marine soils based on dynamic triaxial test

Abstract

The dynamic shear modulus and damping ratio, as important parameters of soil dynamics, are indispensable for the evaluation of seismic safety and analysis of soil layer seismic response. Due to the limited existing research into marine soil’s dynamic shear modulus and damping ratio, there is a failure to get the reference values, along with the reference values for relevant parameters of soil. The soil physical mechanics and dynamic triaxial test research concerning the 25 samples of the Yellow Sea offshore project in Sheyang, Jiangsu Province were made in this paper, where the particle-grade curve of marine soils was also given. According to the current research theory, the method of determining the confining pressure values was explained in detail. Eventually, a linear influence on the maximum dynamic shear modulus with the increase of effective confining pressure was established, following research into the relationship between the maximum dynamic shear modulus and the effective confining pressure, using the hyperbolic model proposed by Hardin. According to the attenuation model relationship of G/G max proposed by Martin, fitting with least square method, the relationship between the dynamic shear modulus and damping ratio of marine soils with shear strain was discussed. The results demonstrate that with the increase of the shear strain, the dynamic shear modulus ratio shows a trend of slight change followed by quick decrease and the damping ratio shows a trend of slow increase followed by quick increase. The reference values for dynamic shear modulus and damping ratios of various marine soils were proposed, via comparison with existing research results. The research results obtained provide basic data for marine soil dynamics and seismic engineering research.