高流速含沙浑水体流变特性试验研究

加速行进中的洪水具有高含沙、高流速和粗粒径的特点，而针对洪水的流变特性研究关注点多为高含沙量，忽略了高流速即高剪切速率的特点。以黄河下游泥沙为研究对象，系统地研究了高流速剪切条件下含沙量、剪切模式、温度和盐度对流变特性的影响。结果表明，在高流速剪切条件下（剪切速率≥ 1200 s-1，对应线性流速为3.6 m/s），含沙量在106.64 ~ 957.83 kg/m3范围内的浑水体符合牛顿流体的应力本构关系，不存在屈服应力，表观黏度与含沙量呈指数关系。温度降低并未改变浑水体的流变特性，但会使其表观黏度增加，且温度越低黏度增幅越大，浑水体黏度增大梯度约为等温度清水的数倍至十几倍。盐度变化对该测试浑水体的表观黏度和流变特性影响甚微，可忽略不计。本研究结果可为高流速水流挟沙和远距离输沙研究提供理论参考。

Experimental study on rheological properties of turbid water with high flow velocity

Flood water in the accelerating section of a sediment-laden river is characterized by high sediment concentration, high flow velocity, and coarse particle sizes. Previous studies on the rheological properties of flood water focuses on high sediment concentration, ignoring the factor of high flow velocity, more preciously high shear rate. This study examines systematically the effects of sediment concentration, shear mode, temperature and salinity on the rheological properties of turbid water in the lower Yellow River under high velocity shear conditions. The results show that under high shear rates (≥ 1200 s-1 at the velocity of 3.6 m/s), the rheological properties of turbid water with sediment concentration of 106.6 - 957.8 kg/m3 follow the laws of Newtonian fluid, no yield stress is observed, and its apparent viscosity has an exponential relationship with sediment concentration. A temperature drop does not change its rheological properties but its apparent viscosity is increased, and lower temperature will result in a greater viscosity increase. At the same temperature, the gradient of viscosity increase is about several times to ten times that of clear water. A change in salinity has little effect on the apparent viscosity or rheological properties. The results are useful for further theoretical study of high velocity flow sediment carrying capacity and long-distance sediment transport.