Formation mechanism of clogging of dredge slurry under vacuum preloading visualized using digital image technology

Vacuum preloading combined with prefabricated vertical drains (PVDs) system has been widely used to improve the soft clay high water content. Clogging is usually formed around PVDs during vacuum preloading, impeding propagation of pressure and slowing down consolidation process. To understand forming mechanism clogging, particle image velocimetry (PIV) technique tracking (PTV) were adopted in model test test. Through this study, three stages can be identified from results volume discharge rate maximum displacements versus time. In first stage, soil PVD horizontally consolidated, which leads rapid formation clogging. second clogging slows due loss pressure, further reduces drainage. third tends stable, drainage significantly reduced. PTV show that there a difference displacement large small particles improvement. Two methods proposed estimate thickness zone, reflecting growing layer zone compressed PVD. This study provides new insights investigate