Rheological Response of Natural Soft Coastal Mud under Oscillatory Shear Loadings

The dynamic rheological properties of natural cohesive sediments are essential to understanding cohesive sediment transport under waves. In this study, dynamic rheological measurements of natural mud collected from Yueqing Bay, Zhejiang province, China, were conducted under oscillatory shear loadings in a laboratory. The mud samples exhibited nonlinear viscoelastic behavior when the strain amplitude was larger than 0.0005. Mud fluidization began at a large strain amplitude because of the significant decrease in complex viscosity. Strain amplitude was found to play an important role in mud fluidization, whereas frequency had limited influence under small-amplitude oscillatory shear. Time-dependent nonlinear stress waveforms were analyzed to further quantify the nonlinear viscoelastic response of natural mud. The nonlinearity of the samples increased with strain amplitude; however, it decreased at extremely large strain amplitudes.