中文摘要：

以紫色土细颗粒泥沙作为研究对象,探讨不同阳离子对紫色土细颗粒絮凝沉降的影响。结果表明：（1）Na＋浓度为0～10mmol/L时,随着浓度升高悬液澄清的时间缩短,浓度为7mmol/L时105min后悬液澄清,当Na＋浓度为10mmol/L时,60～70min达到澄清,临界絮凝浓度在5～7mmol/L之间;（2）Ca2＋浓度较高（0.8～1.0mmol/L）时,其对细颗粒泥沙絮凝沉降的影响逐渐减小;（3）Al 3＋浓度在0～0.3mmol/L时对土壤颗粒沉降速度影响非常显著,〉0.3mmol/L时,沉降速度略有增加,但幅度明显小于初始阶段;（4）3种电解质体系中土壤颗粒发生凝聚过程拐点的排斥压强均在1.3～1.4atm之间。

英文摘要：

Based on purple soil fine particles,the effects of different cation ions on flocculation sedimentation were studied.The results showed that：（1）The fine sediment settles were faster with the increase of NaCl concentration when NaCl concentration was 0～10 mmol/L.The suspension got clearly in 105 minutes and NaCl concentration was 7 mmol/L.The suspension got clearly in 60～70 min and NaCl concentration was 10 mmol/L.The critical coagulation concentration was 5～7 mmol/L.（2）The effect of Ca2＋ on flocculation sedimentation of fine particles was gradually decreased when CaCl2 concentration was 0.8～1.0 mmol/L.（3）Al3＋ had a significant influence on sedimentation rate of fine particles when the concentration of AlCl3 was 0～0.3 mmol/L.When Al3＋ concentration exceeded 0.3 mmol/L,the increasing extent of sedimentation rate was significantly lower than that in initial stage.（4）The repulsion pressure at inflection point of three kinds of electrolyte systems was 1.3～1.4 atm.