Effect of a sealed connector on the improvement of dredged slurry under vacuum preloading

For ground improvement of dredged slurry in a land reclamation area in China, a membrane-connector vacuum preloading method that integrates membrane-based and membrane-free methods was studied by laboratory tests. In this method, airtight membranes over the surface of the dredged slurry are used to maintain the vacuum pressure and prefabricated vertical drains (PVDs) are connected to a horizontal non-porous vacuum pipe by a sealed connector. The efficiency of this new method was compared with that of the traditional PVD-hose method using physical model tests. The effect of varying the PVD spacing on soil improvement was studied and monitoring and detection parameters (vacuum pressure, settlement, pore pressure, water content, vane shear strength and degree of consolidation) were analysed. The test results showed that better treatment results were achieved for the dredged slurry with a very high water content using the membrane-connector method. Additionally, a more optimised choice of PVD spacing is suggested for treating dredged slurry in land reclamation areas.