Analysis of one-dimensional rheological consolidation of double-layered soil with fractional derivative Merchant model and non-Darcian flow described by non-Newtonian index

To further investigate the one-dimensional (1D) rheological consolidation mechanism of double-layered soil, the fractional derivative Merchant model (FDMM) and the non-Darcian flow model with the non-Newtonian index are respectively introduced to describe the deformation of viscoelastic soil and the flow of pore water in the process of consolidation. Accordingly, an 1D rheological consolidation equation of double-layered soil is obtained, and its numerical analysis is performed by the implicit finite difference method. In order to verify its validity, the numerical solutions by the present method for some simplified cases are compared with the results in the related literature. Then, the influence of the revelent parameters on the rheological consolidation of double-layered soil are investigated. Numerical results indicate that the parameters of non-Darcian flow and FDMM of the first soil layer greatly influence the consolidation rate of double-layered soil. As the decrease of relative compressibility or the increase of relative permeability between the lower soil and the upper soil, the dissipation rate of excess pore water pressure and the settlement rate of the ground will be accelerated. Increasing the relative thickness of soil layer with high permeability or low compressibility will also accelerate the consolidation rate of double-layered soil.