Laboratory investigation on the influence of sedimentation state on small-strain shear modulus in marine layered soils

The dynamic parameters of soil within the small strain range (0.0001%-0.1 %) are essential for characterizing the behavior of marine soils. This study investigates the dynamic characteristics of layered soil under small strain using resonant column tests. Specifically, the impact of different sedimentation states, such as soil layer interfaces, pre-consolidation stresses, and consolidation pressures, on the small-strain shear modulus (G0) is explored. A refined empirical formula, building upon the original framework of Hardin's model, is proposed to describe the distribution patterns of the initial shear modulus in layered soils under different sedimentary conditions. Test results indicate that G-gamma degradation curves demonstrate a nonlinear decay pattern with increasing shear strain, and the rate of shear modulus degradation is influenced by pre-consolidation stress and consolidation pressure. The position of the interface between different soil layers has a relatively minor effect on the shear modulus. The modified Hardin formula successfully captures the initial shear modulus for layered soil under different pre-consolidation stresses. It is observed that the marine layered soil distribution pattern of the initial shear modulus tends to exhibit a more linear variation due to soil layer interfaces influence, which can be well-fitted using a linear formula. Furthermore, the sedimentation and layering state of the soil affect the smallstrain parameters G0 and gamma 0.7. Consequently, the layering structure of marine soils should be carefully considered when simplifying geological models for engineering design and construction.