絮凝剂作用下黏性细沙絮凝沉降规律研究

细颗粒泥沙广泛分布于河流、水库、河口及海岸水体中，其絮凝沉降及输移规律是泥沙运动力学中一个重要课题。采用自制沉降实验装置，实验观测了不同絮凝剂浓度、不同浓度黏性细颗粒泥沙的絮凝沉降过程，分析研究了黏性细沙絮凝沉降规律。结果表明：聚合氯化铝(PAC)絮凝剂比较稳定，PAC溶液浓度对不同泥沙浓度絮团沉速的影响均较小，最佳投放浓度可统一采用0.08 g/L。阳离子型聚丙烯酰胺(CPAM)絮凝剂对泥沙浓度的反应最为敏感，絮凝剂最佳投放浓度随着泥沙浓度的变化分为3个稳定段和2个敏感段，稳定段CPAM最佳投放浓度分别为0.08、0.10和0.12 g/L，敏感段CPAM最佳投放浓度可采用区间插值方法选取。阴离子型聚丙烯酰胺(APAM)絮凝剂最佳投放浓度随着泥沙浓度的变化分为2个稳定段和1个敏感段，稳定段APAM最佳投放浓度不随泥沙浓度的变化而变化，分别为0.08和0.10 g/L，敏感段APAM最佳投放浓度可采用区间插值方法选取。絮凝剂APAM的絮凝效果最好，絮凝剂CPAM的絮凝效果次之，絮凝剂PAC的絮凝效果较差。

Flocculation and sedimentation of cohesive fine-grained sediment under the action of flocculants

Fine-grained sediment is commonly found in rivers, reservoirs, estuaries and offshore water bodies, and its flocculation and sedimentation is an integral part of mechanics of sediment transport. Here, experiments were conducted to monitor the flocculation and sedimentation process of cohesive fine-grained sediment with different concentrations of flocculants and sediment using a homemade experimental device, according to which the flocculation and sedimentation law of cohesive fine-grained sediment was analyzed and studied. The results show that among the flocculants, polyaluminum chloride (PAC) is relatively stable, and its optimal dosage does not change with the change of sediment concentration, which remains at 0.08 g/L. As for cationic polyacrylamide (CPAM), it is the most sensitive to sediment concentration, and the optimal dosage concentration of the flocculant can be divided into three stable stages and two sensitive stages with the change of sediment concentration; the optimal dosage concentrations corresponding to different sediment concentrations are 0.08, 0.10 and 0.12 g/L at the stable stages, respectively, and those at the sensitive stages can be selected using interval interpolation. In regards to anionic polyacrylamide (APAM), its optimal dosage concentration can be divided into two stable stages with the change of sediment concentration, and the optimal dosage concentration does not change with the change of sediment concentration during the stable stages, which is 0.08 and 0.10 g/L, respectively. In addtion, the optimal dosage concentration of APAM at the sensitive stage can be selected by interval interpolation as well. APAM has the best flocculation effect, followed by CPAM , whereas PAC performs poorly.