This paper presents a theoretical framework for approximating the gelling concentration in suspensions, with a focus on its application to the parameterization of soil consolidation processes in coastal sediment environments. The model is based on the integration of principles from rheology, colloid science and sedimentology, and the analysis of the change in rheological viscosity as a function of volumetric sediment concentration. Validation is performed against measured rheological data and shows that the model is able to accurately approximate the gelling concentration of sediment under varying environmental conditions. The model provides valuable insights into the consolidation dynamics of saturated soils in estuaries by linking micro-scale sediment properties and macro-scale geotechnical phenomena. In addition, amore robust constitutive equation for estimating effective stress was developed that accounts for both permeability and effective stress regimes by incorporating the underlying physics of each. The results show that the proposed model closely aligns with the conceptual model of sediment concentration profile, accurately depicting the transition from fluid mud to consolidated bed, and capturing the irregularities and inflection points in sediment concentration that were not represented in previous models.

Sand columns have been widely used to accelerate drainage and then improving the mechanical properties of soft soil foundations. The sand column has also been introduced into the triaxial test by researchers, in the center of the cylindrical specimen, to greatly accelerate drainage and consolidation process. The objective of this paper is to evaluate the consolidation properties of the triaxial cylindrical specimen considering the presence of a sand column, and then to propose a consolidation model that simulates the consolidation process of the triaxial test. The consolidation equations were derived considering the drainage of the specimen with a sand column composed of both vertical and double-radial flows. Then the analytical solution of the model was obtained based on specific initial and boundary conditions. The comparison between the consolidation model and the laboratory tests yielded highly consistent. The case study demonstrated that the proposed consolidation model accurately simulates the evolution of average pore pressure and degree of consolidation in triaxial specimens containing a sand column. The studies on the consolidation parameters showed that there were different effects on the drainage rate for the diameter of specimen, the permeability coefficients of specimen and sand column, as well as the radius of the sand column.