Influence of DOC of vacuum preloading on dynamic consolidation for dredged slurry

Abstract

Generally, marine reclamation land needs to be improved by a large margin before the construction of civil structures in coastland due to poor geotechnical properties of the dredged slurry. The combination of vacuum preloading (VP) and dynamic consolidation (DC) has been developed for application in such projects. However, the effect of the combined VP and DC method is mainly controlled by the start-up time of DC (time of first tamping); in this study, the start-up time was determined by the degree of consolidation (DOC), and the DOC under VP was estimated by pore water pressure (PWP). According to a series of previously studied laboratory test results, the DC can be applied when DOC is greater than or equal to 60%. Thus, DOCs of 60%, 65%, 70%, and 75% were considered as the judgment index of start-up time. During the model tests, the settlement and PWP were monitored and measured. The water content and vane shear strength of the dredged slurry were also measured after the completion of tests. The start-up time of DC was determined when an optimal DOC was 70%.