Wang Dangwei, Liu Xiaofang, Ji Zuwen, Dong Zhandi, Hu Haihua
State Key Laboratory of Simulation and Regulation of River Basin Water Cycle, China Institute of Water Resources and Hydropower Research, Beijing, China.
Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China E-mail:
Water Sci Technol. 2016;73(4):873-80. doi: 10.2166/wst.2015.562.
By comparing the original particle gradation of sediment from the Three Gorges Reservoir with the single particle gradation, the differences in these two particle gradations showed that there is sediment flocculation in the Three Gorges Reservoir, which can accelerate the sediment deposition rate in the reservoir. In order to determine the influence of flocculation on the sediment settling velocity, sediment was collected at the Three Gorges Reservoir, and the indoor quiescent settling experiment was performed to study the mechanism of sediment flocculation. The experimental results showed that sediments aggregated from single particles into floccules in the settling processes. The single particles smaller than 0.022 mm will participate in the formation of floccules, which accounts for 83% of the total amount of sediment in the Three Gorges Reservoir. Moreover, the degree of sediment flocculation and the increase in sediment settling velocity were directly proportional to the sediment concentration. Taking the average particle size and the median particle size as the representative particle size, respectively, the maximum flocculation factors were calculated to be 3.4 and 5.0. Due to the sediment flocculation, the volume of sediment deposition will increase by 66% when the mass settling flux factor of total sediment had a maximum value of 1.66, suggesting that flocculation has a significant influence on the sediment deposition rate in the Three Gorges Reservoir.
通过将三峡水库沉积物的原始颗粒级配与单颗粒级配进行比较，这两种颗粒级配的差异表明三峡水库存在泥沙絮凝现象，这会加速水库内的泥沙淤积速率。为了确定絮凝对泥沙沉降速度的影响，在三峡水库采集了泥沙，并进行室内静置沉降试验以研究泥沙絮凝机制。试验结果表明，泥沙在沉降过程中由单颗粒聚集成絮体。小于0.022毫米的单颗粒会参与絮体的形成，其占三峡水库泥沙总量的83%。此外，泥沙絮凝程度和泥沙沉降速度的增加与泥沙浓度成正比。分别以平均粒径和中值粒径作为代表性粒径，计算出的最大絮凝系数分别为3.4和5.0。由于泥沙絮凝，当总泥沙的质量沉降通量系数最大值为1.66时，泥沙淤积量将增加66%，这表明絮凝对三峡水库的泥沙淤积速率有显著影响。
