Vacuum Filtration Theory for Slurry Considering Bidirectional Deformation Based on Elliptical Cylinder Model

ABSTRACT Vacuum preloading combined with prefabricated vertical drains is commonly used for enhancing the high water content slurry. However, the process of slurry dewatering, which is inherently a filtration problem, is difficult to describe using consolidation theories. This study presents a new vacuum filtration theory for slurry based on the elliptical cylinder model, where the radial and vertical deformations are governed by the equal settlement assumption. To describe the permeability and compressibility of slurry, the extended power function equations are adopted. The governing equations associated with the influenced zone and the moving boundary are essential components of the vacuum filtration theory, which are solved by the finite difference method. The applicability of the theory is confirmed by comparing the results of it with the laboratory tests and the radial filtration theory. Depending on the properties of the slurry used in the laboratory tests, the filtration behaviour are analysed. Finally, parametric analysis is carried out to investigate the effect of vacuum pressure on the filtration behaviour of the slurry.