A general FEM framework for sedimentation and consolidation of diluted clay suspensions

Abstract

Soft fine-grained sediments placed by hydraulic dredging usually pass through two main stages: an initial sedimentation stage, where particles settle in suspension, and a later self-weight consolidation stage, where interparticle contacts develop and pore water is progressively expelled. In engineering practice, these two stages are often treated separately, which makes it difficult to describe the full evolution of very soft deposits within a single consistent model. This paper presents a unified finite element framework for sedimentation and consolidation of diluted clay suspensions. The formulation is based on a common set of governing equations and constitutive relations, allowing both regimes to be described within one continuous advection–diffusion framework. A smooth transition around the gelling concentration is introduced to avoid a discontinuous switch between sedimentation and consolidation, and a SUPG stabilization is used for advection-dominated transport. The model is applied to kaolinite K1 and Marker Wadden mud, and the results are compared with experimental measurements of interface evolution, density profiles, and drainage-induced settlement. The framework reproduces the main trends observed in both one-dimensional settling columns and drainage-controlled configurations. In addition, the formulation is compared with a large-strain finite element reference model using logarithmic compressibility, showing that the proposed approach remains consistent with more advanced hydro-mechanical descriptions while retaining a simpler constitutive structure that avoids tensorial stress updates, return-mapping algorithms, and additional internal variables. The proposed framework provides a practical tool for analyzing the evolution of very soft sediments from suspension to consolidated soil in geotechnical and land reclamation applications.