PAM类有机絮凝剂对高黏粒含量废弃泥浆脱水性能影响研究

针对泥水盾构长距离穿越粉质黏土地层时产生的大量高黏粒含量泥浆难以快速脱水的问题，开展PAM类有机絮凝剂与泥浆混合后的絮凝沉降试验，研究泥浆中颗粒沉降速率的变化，通过颗粒粒径、上清液浊度和Zeta电位等性质变化分析絮凝沉降效果的差异，并通过比阻试验评价其脱水性能。结果表明： 1）阳离子型聚丙烯酰胺（CPAM）添加量为0.12%~0.15%、阴离子型聚丙烯酰胺（APAM）添加量为0.06%~0.09%时絮凝沉降效果较好，可在2 h之内降低泥浆约10%的水分； 2）非离子型聚丙烯酰胺（NPAM）无法有效降低泥浆含水率； 3）PAM类絮凝剂通过团聚泥浆中黏土颗粒形成大尺寸的絮团，是实现泥浆快速絮凝沉降的关键因素，APAM对泥浆Zeta电位影响较小，CPAM添加量的增加使Zeta电位逐渐减小； 4）PAM类絮凝剂可加快泥浆的前期排水速率，使泥浆比阻值降低至1013 cm/g数量级。

Influence of Polyacrylamide Organic Flocculant on Dewatering Performance of Waste Slurry with a High Content of Clay Particles

The rapid dewatering of a large amount of waste slurry with high clay content produced during slurry shield tunneling in silty clay formation is highly important. To achieve this, flocculation and sedimentation test is conducted on the slurry mixed with polyacrylamide (PAM) organic flocculant to study the variations in the sedimentation rate of the slurry particles. The settlement effect differences of the flocculant are evaluated by analyzing the variation in particle size, supernatant turbidity, and Zeta potential, while the dewatering performance is studied through specific resistance test. The results demonstrate the following: (1) To reach good flocculation and sedimentation effects, the added amount of cationic PAM (CPAM) is 0.12%~0.15% and that of anionic PAM (APAM) is 0.06%~0.09%; the moisture content of the slurry could be reduced by 10% within 2 h. (2) Nonionic PAM does not effectively reduce the water content of the slurry. (3) PAM flocculants agglomerate the clay particles in slurry to form large size flocs, which is a key factor in realizing the rapid flocculation and settlement of the slurry. APAM has little effect on the Zeta potential of the slurry, whereas an increase in CPAM gradually decreases the Zeta potential. (4) The PAM flocculant can accelerate the early drainage rate of the slurry and reduce the specific resistance of the slurry to a magnitude of 1013 cm/g.