Analysis for vacuum consolidation of soil incorporating clogging effect, varying permeability and compressibility

This paper investigates the clogging effect of soil pile in vacuum preloading of dredged soil combined with a prefabricated vertical drain (PVD) through laboratory model tests and analytical model. Variation in water content and permeability of soil around the PVD clarify the formation of soil pile. Seepage and consolidation tests with a formed soil pile indicate that the clogging effect slows down the drainage of pore water rather than stops it. Taking soil pile as a filter layer, an analytical model is established incorporating the clogging effect, varying permeability and compressibility of soil. Finally, based on comparison between existing cases and the analytical model, an empirical linear relationship is suggested for estimating the likely range of the permeability and scale of soil pile against the reduction of void ratio in the vacuum- assisted consolidation of soil. It is clarified that the proposed model with suggested parameters could simulate the consolidation process of soil with high water content appropriately. The soil pile with lower permeability or larger diameter leads to more serious clogging effect on the consolidation of soil. The development in clogging effect due to the extension of soil pile decreased persistently.