Coupled model for one-dimensional nonlinear consolidation and contaminant transport in a compacted clay liner considering mechanical-chemical loading

For the coupled process of one-dimensional consolidation and contaminant transport in a compacted clay liner under mechanical-chemical loading, the corresponding coupled model is established by considering the nonlinear changes of compressibility and permeability of soils, and the finite difference method is adopted for solving the model. The correctness of the proposed coupled model is validated by comparing its results with the calculation ones of the finite element software COMSOL Multiphysics and the existing analytical solution. Based on the proposed model, the effects of mechanical loading p_u and contaminant concentration C_b in leachate on the coupled process under two assumptions are compared and investigated. The results show that when the nonlinear compressibility and permeability characteristics are neglected, the increase of p_u reduces the transport rate of contaminants. However, when the nonlinear compressibility and permeability characteristics are considered, the increase of p_u leads to the increase of transport rate, which is mainly due to the comprehensive effects of advection and diffusion on the transport process. The increase of C_b increases the settlement, reduces the excess pore water pressure and decreases the transport rate of contaminants. Compared with the case of ignoring nonlinearity, the effects of C_b on the settlement, excess pore water pressure and transport rate of contaminants are reduced when the nonlinearity is considered.