泥沙研究

根据三峡库区悬沙特性配制试验沙样，利用粒子追踪系统在大型水箱中开展絮凝试验。结果表明，絮凝作用下泥沙粒子通过搭接形成了不同形状的多孔结构，直接影响絮团的密实程度。存在最佳紊动剪切率使絮团发育达到峰值，其值介于12～18 s^-1之间，低于最佳紊动剪切率时，絮团中值粒径随剪切率的增大而增大，高于最佳紊动剪切率时，絮团中值粒径随剪切率的增大而减小；随着初始含沙量的增加，当紊动剪切率较低时，絮团中值粒径先增大后减小，平均分形维数则先减小后增大；当紊动剪切率较高时，絮团中值粒径整体上呈减小趋势，平均分形维数整体上呈增大趋势。

Based on the characteristics of suspended sediment in the Three Gorges Reservoir, the test sediment samples were made up and flocculation tests using PTV had been conducted in a large water tank. The results show that the porous structure with different shapes can be formed through lapping in sediment particles during flocculation, which directly affects the compactness of flocs. There exists an optimal turbulent shear rate for floc development to peak, with values between 12 s^-1 and 18 s^-1, the median particle size of flocs increases with the increasing of shear rate when the turbulence shear rate is lower than the optimal value, the median particle size of flocs decreases with the increasing shear rate when the turbulence shear rate is greater than the optimal value. With the initial sediment concentration increasing, the median diameter of flocs tends to increase and then decrease, while the average fractal dimension tends to decrease and then increase when the turbulent shear rate is lower; The median diameter of flocs tends to decrease, while the average fractal dimension tends to increase when the turbulent shear rate is higher.