Abstract: In the current large-strain consolidation theory of double-layer soft soil foundation, it is assumed that the seepage in the soil follows Darcy’s law. However, it has been recognized that the seepage in soft clay may deviate from Darcy’s law under low hydraulic gradient. The effects of non-Darcy flow, non-linear characteristics, and time-dependent loading are discussed comprehensively, and a model for the finite-strain consolidation is developed in Lagrangian coordinate by employing the excess pore water pressure as variable. Meanwhile, the corresponding finite difference solutions for this model are provided. On this basis, the numerical solutions for the proposed consolidation model are verified by comparing with the numerical solutions for the large-strain consolidation of a single soil layer foundation with non-Darcy’s law. The influences of upper layer parameters m1、i11 and sublayer parameters m2, i12 on consolidation behaviors and the differences in the dissipation of excess pore water pressure and in the consolidation settlement are investigated. The results show that the influences of m1, i11 on consolidation behavior are more evident than m2, i12. The dissipation rate of excess pore water pressure in upper layer increases with the increase in the value of m2 or i12, whereas the consolidation rate of double layer foundation decreases with the increase in the value of m2 or i12. The consolidation rate of double layer foundation under large-strain assumption is larger than that at small-strain, whereas the final settlements under both large-strain assumption and small-strain assumption are the same.

Key words: double-layer foundation, non-Darcy’s flow, large-strain consolidation, nonlinear consolidation, finite difference method