Experimental investigation of dynamic shear stiffness and damping ratio characteristics of marine soils: A case study 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 ( l ) 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 l 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 l . Analysis based on the Davidenkov model revealed that parameters α and β are insensitive to H , while the characteristic strain g 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.