长江口航道淤泥流变特性试验研究

为揭示长江口航道淤泥的流变特性，采用Anton Paar MCR302旋转流变仪对长江口航道疏浚淤泥的剪切动力响应进行试验研究，分析容重范围为1.16~1.72 g/cm3的淤泥的基本流变特性及其对容重、盐度、pH值与温度等的响应特性。结果表明:在剪切荷载作用下，长江口航道淤泥具有双宾汉体特性，其剪切应力与剪切速率间的关系可基于Dual-Herschel-Bulkley流变模型进行定量描述；随着剪切加载速率的增大，淤泥表现出复杂的固—液相态转化现象，其动力响应过程可划分为类固态、固—液转化和液态3个典型阶段，分别具有弹性体、黏弹性体和塑性体的变化特征；淤泥的抗剪强度随容重、盐度和pH值的增加而增强，随温度的升高而降低，并以容重的影响最为显著；基于实测结果建立了描述长江口航道淤泥流变特性的经验本构方程，可用于定量分析潮汐和波浪作用下底床淤泥的运动变化。

Experimental study on rheological properties of soft mud in Yangtze River Estuary

In order to clarify the soil mechanical properties of soft mud in the Yangtze River Estuary under shear loads,experimental study by using Anton Paar MCR302 rotary rheometer was conducted to examine the rheological responses of the mud to shear forces,especially on the basic rheological property of the mud with bulk density ranging from 1.16 to 1.72 g/cm³,as well as the associated influences of bulk density,salinity,pH value and temperature. The results showed that under the action of shear loads,the mud in the Yangtze River Estuary exhibits Bingham fluid characteristics,and the relationship between shear stress and shear rate can be quantitatively described based upon the Dual-herschel-bulkley rheological model. With the increase of shear rate,the complex phase transformation process from solid to liquid of the mud was observed which can be classified into three typical stages:solid-like stage,solid-liquid transition stage and liquid-like stage,corresponding to the elastic,viscoelastic and plastic material respectively. The shear strength of the mud increases with the increase of bulk density,salinity and pH value,and decreases with the increase of temperature. Finally,with the measured results,an empirical constitutive equation was established to describe the rheological behaviors of the mud,that can be applied for quantitative analysis of the mud movement under hydrodynamic forces such as tides and waves.