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 γ 0 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.