Two-Dimensional Nonlinear Consolidation of Saturated Clay Considering Anisotropic Hansbo’s Flow

Abstract

The permeability in the natural clay layer is obviously anisotropic, and the flow of water in the pores often deviates from Darcian law. In order to analyze the effect of anisotropic non-Darcian flow on the two-dimensional consolidation of a saturated clay layer, the vertical and horizontal permeability laws of saturated clay were measured by the falling-head permeability test. It was found that the flow of water in both directions can be described by Hansbo’s flow equation, and Hansbo’s flow parameters in these two directions were obviously different. Then, the two-dimensional Terzaghi consolidation equations were modified considering the anisotropic Hansbo’s flow and discretized into finite-element formulations. The validity of the numerical model was verified through comparison with the literature solutions. The effect of the anisotropic Hansbo’s flow on the consolidation process of a two-dimensional saturated clay layer was analyzed under different lower boundary conditions. The numerical results indicated that in the initial stage of consolidation, the excess pore pressure is slightly concentrated in a specific area below the loading boundary. Moreover, variations in the lower boundary conditions have little effect on the distribution of excess pore pressure, and the influence of the different Hansbo’s flow parameters in the vertical direction on the dissipation rate of excess pore pressure is not evident. However, in the middle and late stages of consolidation, the pore-water pressure with the permeable lower boundary condition is significantly lower compared to that with the impermeable lower boundary condition. Additionally, increasing the values of Hansbo’s flow parameters in the vertical direction further impedes the dissipation rate of excess pore pressure, which in turn slows down the consolidation process of the clay layer.