Experimental investigation of dynamic shear stiffness and damping ratio characteristics of marine soils in Lingdingyang Bay, China

Shear wave velocity (V_s), maximum dynamic shear modulus (G_max), dynamic shear modulus ratio (G/G_max), and damping ratio (λ) are critical parameters for determining seismic ground motion characteristics in submarine sites. Based on the V_s profiles measured from boreholes in a specific marine area, this study investigated the applicability of existing empirical equations (linking V_s with soil depth, H) for marine soils in this region. Laboratory resonant column tests were conducted to analyze variations in G_max, G/G_max, and λ at different depths (H). The results demonstrated that the quadratic polynomial relationship between V_s and H for terrestrial soils is applicable to sandy soils in the bay but not to cohesive marine soils in the same area. By incorporating soil density (ρ), a new V_s prediction equation suitable for cohesive marine soils in the bay was established. Additionally, marine soils exhibited low shear modulus and high damping ratios, with reduced nonlinearity and hysteresis effects as H increased, leading to higher G and lower λ. Analysis based on the Davidenkov model revealed that parameters α and β are insensitive to H, while the characteristic strain γ₀ increases linearly with H. These findings provide reliable references for the prediction of V_s and the evaluation of dynamic properties of marine soils in the Lingdingyang Bay.