Reinforcement Effect and Mechanism Analysis of Dredged Sludge Treated by Alternating Prefabricated Radiant Drain Vacuum Preloading Method

The vacuum preloading method is widely applied in dredged sludge reinforcement, however, prefabricated vertical drain (PVD) clogging affects the effectiveness of ground reinforcement and leads to significant uneven settlement. To alleviate these deficiencies, this paper proposed an alternating prefabricated radiant drain vacuum preloading (APRD-VP) method considering the advantages of the alternating vacuum preloading (A-VP) method (delaying clogging) and prefabricated radiant drain vacuum preloading (PRD-VP) method (combining horizontal drainage and alleviating uneven settlement). The laboratory model experiments were conducted to explore the treatment effect of APRD-VP method, and the particle image velocimetry technology was employed to observe clogging range surrounding PVD. The experimental results demonstrate that APRD-VP method displayed a better reinforcement effect than the traditional method by analysis of water discharge, settlement, pore water pressure, water content, and vane shear strength. By investigating the clogging formation development for APRD-VP method, the maximum clogging range on both sides of the drainage board has been reduced by 3.15% and 14.02%. In addition, the empirical relationship between clogging range and settlement was established to can better judge and predict clogging range, which can lay the foundation for establishing the theory of computation of soft soil ground design suitable for APRD-VP method.