The ultimate yield stress of cohesive sediments changes with oscillatory loading or vibration. Given a strong enough vibration, the sediment may be fluidized. In this study, the effect of the frequency of minute-amplitude oscillatory shear loadings on the ultimate yield stress of cohesive sediments was experimentally and analytically investigated in a laboratory. The test samples were prepared with cohesive sediments with a median particle size of 31 μm and at four water content (31.8% to 37.03%). The sediments were subjected to continuous oscillatory shear loadings with a constant frequency (0–131.6 Hz). The findings of the study indicated that the ultimate yield stress of cohesive sediments under minute-amplitude oscillatory shear loadings was dependent on the oscillatory shear frequency, water content, and the ultimate yield stress of the sediments prior to the application of the oscillatory shear loading. This study revealed that there exists a critical shear loading frequency f_cr. When the oscillatory shear frequency (f) was less than the critical shear frequency (f_cr), the ultimate yield stress decreased as f increased. However, when f was greater than f_cr, the ultimate yield stress was constant, irrespective of further increase of the oscillatory shear frequency. The former condition is identified as the non-equilibrium fluidization stage and the latter, the equilibrium fluidization stage. The f_cr value decreased as the water content increased. In the equilibrium fluidization stage, the dimensionless yield stress $Su/S{u}_0$ did not vary with the water content or oscillatory shear frequency. Two discrete formulae were proposed to estimate the ultimate yield stress of cohesive sediments subjected to minute-amplitude oscillatory shear loadings for the non-equilibrium and equilibrium fluidization stages. To explore the engineering applications of the formula for the equilibrium fluidization stage, a series of vertical pull out tests were performed using a dynamic torpedo anchor. This study provides an important method for distinguishing the degree of fluidization and sheds lights on potential applications in coastal and marine engineering, such as pile or anchor installation and extraction and scour protection in cohesive bed.

粘性沉积物的极限屈服应力随振荡载荷或振动而变化。如果振动足够强，沉积物可能会流化。在这项研究中，微幅振荡剪切载荷的频率对粘性沉积物的极限屈服应力的影响在实验室中进行了实验和分析研究。测试样品由中值粒径为 31 μm 的粘性沉积物制备​​，具有四种含水量（31.8% 至 37.03%）。沉积物受到恒定频率 (0–131.6 Hz) 的连续振荡剪切载荷 ）。研究结果表明，粘性沉积物在微幅振荡剪切载荷下的极限屈服应力取决于振荡剪切频率、含水量和施加振荡剪切载荷之前沉积物的极限屈服应力。该研究表明，存在临界剪切载荷频率f _cr。当振荡剪切频率 ( f ) 小于临界剪切频率 ( f _cr ) 时，最终屈服应力随着f 的增加而降低。然而，当f大于f _cr，最终屈服应力是恒定的，与振荡剪切频率的进一步增加无关。前者称为非平衡流化阶段，后者称为平衡流化阶段。所述˚F _CR随着水含量的增加值下降。在平衡流化阶段，无量纲屈服应力$秒你/秒{你}_0$不随含水量或振荡剪切频率而变化。提出了两个离散公式来估计非平衡和平衡流化阶段受到微幅振荡剪切载荷的粘性沉积物的极限屈服应力。为了探索平衡流化阶段公式的工程应用，使用动态鱼雷锚进行了一系列垂直拉拔试验。该研究为区分流化程度提供了重要方法，并揭示了沿海和海洋工程中的潜在应用，例如桩或锚的安装和提取以及粘性床的冲刷保护。