水平排水板–真空预压联合处理高含水率疏浚淤泥模型试验研究

Experimental investigations on treatment of dredged slurry by vacuum-assisted prefabricated horizontal drains

水平排水板(prefabricated horizontal drain,PHD)联合真空预压是处理疏浚淤泥的有效手段,在浅层专用对堆置场的应用中具有很大优势。通过2个室内模型对照试验,研究了竖向排水板(prefabricated vertical drain,PVD)和水平排水板联合真空预压处理高含水率疏浚淤泥的差异性。研究主要分析了真空荷载下PVD和PHD的排水特点、试验中模型土体的沉降和板材变形情况以及试验结束时的土样含水率等结果,试验表明使用水平排水板处理疏浚淤泥可有效避免板材的弯折问题,且试验过程中土体变形非常均匀;随着固结过程水平排水板上下土层厚度不断减少,缩短了排水路径,PHD固结模型试验的整体排水速率高于PVD固结;380 h真空固结以后,水平排水板处理的疏浚淤泥含水率从360%降为150%相较于PVD固结低30%～40%。最后,针对模型试验和现场工程实际之间可能的差异性,对试验结果进行了详细讨论,以期可以为更大尺寸的模型、现场试验提供指导。

The combined prefabricated horizontal drains(PHDs)with vacuum preloading is an effective method to treat the dredged clayey soils and shows significant advantages in shallow licensed storage dumps especially.This paper investigated the consolidation/dewatering characteristics of dredged high-water-content clay slurry using prefabricated vertical drains(PVDs)and prefabricated horizontal drains assisted by vacuum preloading.The dewatering capacity,surface settlement,bending of drains and water content after consolidation were recorded and analyzed.Compared with PVDs,the PHDs effectively avoided bending and thus resulted in a very uniform deformation within the model ground.The thickness of soil domain above and below the PHD decreased with time which accelerated the vacuum consolidation indicated by the dewatering rate from tests.The PHD showed a better treatment than PVD,and the water content of model soil decreased from an initial value of 360%to 150%in PHD consolidation which is 30%–40%lower than PVD consolidation.The possible differences between model tests and field cases due to size effect were discussed finally.