絮凝-水平真空两段式脱水法处理高含水率疏浚淤泥模型试验研究  

Model test on dewatering of high-water-content dredged slurry by flocculation-horizontal vacuum two-staged method

作　　者：蒲诃夫[1] 潘友富 KHOTEJA Dibangar 周洋 PU He-fu;PAN You-fu;KHOTEJA Dibangar;ZHOU Yang(School of Civil Engineering and Mechanics,Huazhong University of Science and Technology,Wuhan,Hubei,430074,China;College of Civil Engineering,Henan University of Technology,Zhengzhou,Henan 450001,China)

机构地区：[1]华中科技大学土木工程与力学学院,湖北武汉430074 [2]河南工业大学土木工程学院,河南郑州450001

出　　处：《岩土力学》2020年第5期1502-1509,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51678268,No.51878312,No.51908235);全国博士后科学基金资助面上项目(No.2018M632863)。

摘　　要：针对目前预制竖向排水板(PVD)真空预压法处理疏浚淤泥(软土)时存在的板材弯折和淤堵严重的问题,提出了一种絮凝沉积-水平真空两段式脱水法处理高含水率疏浚淤泥。首先,开展PVD和水平排水板(PHD)对比模型试验,表明PHD相对于PVD具有板材变形小、脱水速率均匀、长期脱水效果好等优点。就研究案例而言,PVD的最终排水量仅为PHD的77.4%。然后,研究了絮凝剂(阴离子型聚丙烯酰胺即APAM)对絮凝沉积-水平真空两段式脱水法排水性能的影响,研究显示絮凝剂的添加可以大幅提高疏浚淤泥的脱水效率。絮凝剂主要通过沉积脱水降低含水率以及絮凝簇团作用改善土体的不均匀固结问题两个方面来整体提高脱水效率;相较于没有添加絮凝剂的试验组,适量添加絮凝剂(0.45%干土质量)可缩短35%的脱水时间。最后,分析了静置沉积时长(即真空介入时间点)对脱水速率的影响。结果表明真空介入过早不利于絮凝剂发挥最大脱水效果且易带来明显的不均匀固结问题,最佳介入时间为静置沉积24 h后。A two-stage method for dewatering high-water-content dredged slurry by flocculation and vacuum-assisted prefabricated horizontal drain(PHD) was proposed to increase the dewatering efficiency by addressing the issues of serious bending and clogging that are typically encountered when using the prefabricated vertical drain(PVD). Firstly, comparison of model tests using PVD and PHD, respectively, under vacuum preloading indicates that the PHD has advantages of uniform settlement of soil, negligible bending of the drain board, uniform dewatering rate and better dewatering efficacy. For the cases considered in this study, the mass of water drained out by PVD was only 77.4% of that by PHD. Effect of flocculation on the dewatering efficacy was investigated and the results indicated that impact of the flocculant(APAM) dosage on the dewatering rate was significant. With moderate addition of APAM(e.g., 0.45% of dry soil mass), the time required for dewatering was shortened by 35%. Lastly, the influence of sedimentation time(i.e., waiting time before applying vacuum pressure) on dewatering rate was studied. The results showed that if the sedimentation time is insufficient, the effect of flocculation cannot be mobilized fully, and as a result, will lead to significant non-uniform consolidation and reduced dewatering efficacy. The best time to start the vacuum pressure is 24 hours after the beginning of sedimentation.

关 键 词：水平排水板 真空预压 絮凝 模型试验 

分 类 号：TU411[建筑科学—岩土工程]