Large-strain numerical solution for coupled self-weight consolidation and contaminant transport considering nonlinear compressibility and permeability

• Published in: Applied Mathematical Modelling Vol. 88; pp. 916 - 932
• Main Authors: Pu, Hefu, Wang, Kun, Qiu, Jinwei, Chen, Xunlong
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 01.12.2020; Elsevier BV
• Subjects: Advection; Consolidation; Contaminant transport; Contaminants; Diffusion coefficient; Dispersion; Dredging; Exact solutions; Finite difference method; Numerical models; Numerical solution; Permeability; Pollution transport; Porous media; Saturated deforming porous media; Sediments; Self-weight consolidation; Soil compressibility; Soil contamination; Soil permeability; Soil porosity; Soils; Transport equations; Transport processes; Weight; Saturated deforming porous media; Contaminant transport; Self-weight consolidation; Numerical solution
• ISSN: 0307-904X; 1088-8691; 0307-904X
• DOI: 10.1016/j.apm.2020.07.010

•The self-weight induced consolidation can significantly accelerate the outflow of contaminants in dredged sediment.•The sediment compressibility can significantly affect the contaminant transport process in dredged sediment.•The sediment permeability can significantly affect the contaminant transport process by affecting the rate of consolidation.•Treating the self-weight loading as external surcharge loading can underestimate the rate of contaminant outflow. Based on the one-dimensional (1D) consolidation equation and advection-dispersion transport equation, this paper presents a large-strain numerical solution for coupled self-weight consolidation and contaminant transport in saturated deforming porous media considering nonlinear compressibility and permeability relationships. The finite difference method is used to solve the governing equations for consolidation and transport. The proposed numerical solution for consolidation accounts for vertical strain, soil self-weight, and nonlinearly changing compressibility and hydraulic conductivity during consolidation. The solution for solute transport accounts for advection, diffusion, mechanical dispersion, linear and nonlinear equilibrium sorption, and porosity-dependent effective diffusion coefficient. The proposed numerical solution is verified against a self-weight consolidation field tank test, an analytical solution in the literature, and the CST1 numerical model. Using the verified solution, a series of parametric study is conducted to investigate the effect of several important parameters on the contaminant transport process for confined disposal of dredged contaminated sediments. The results indicate that the consolidation process and contaminant transport process induced by soil self-weight- can be very different from those induced by the more traditional external surcharge loading. Treating the self-weight loading as traditional external surcharge loading can underestimate the rate of contaminant outflow, especially in the early times. The compressibility and permeability relationships of sediment and the type of loading (i.e., self-weight loading versus external surcharge loading) can all significantly affect the contaminant transport process for confined disposal of dredged contaminated sediment.