Coupled filtration-consolidation model for vacuum-preloaded soft ground

Abstract

The widespread utilisation of vacuum-assisted prefabricated vertical drains (PVD) for managing clayey soft ground has led to the development of numerous consolidation models. However, these models have limitations when describing the filtration behaviour of soil under high water content conditions, without the formation of a particle network. To effectively address this issue, in this work, based on the compressional rheology theory, a two-dimensional axisymmetric model incorporating the compressive yield stress Py(ϕ) and a hindered setting factor r(ϕ) was developed to couple the filtration and consolidation of soil under vacuum preloading. A novel approach for determining the unified ϕ-Py-r relationships was introduced. The equation governing such fluid/solid and solid/solid interactions was solved using the alternative direction implicit (ADI) method, and the numerical solutions were validated against the 1-D filtration cases, 3-D laboratory model tests, and large-scale field trials. Further parametric analysis suggests that the radius of the representative unit and r(ϕ) exclusively affect the dewatering rate of the clayey slurry, while the gel point and Py(ϕ) influence both the dewatering rate and the final deformation.