Abstract: Given the limitations of semi-logarithmic model in describing the nonlinear compression and permeability relationship of large-strain soft soil, we present a bilogarithmic compression and permeability model specifically designed for such conditions. Furthermore, we established a one-dimensional large-strain consolidation equation for saturated soft soil foundation, taking into account non-Darcy flow, and provided a finite difference numerical solution. Through a comparison with indoor testing and analytical solutions, we verified the reliability of this solution. On this basis, we analyzed the effects of seepage parameters, bilogarithmic compression and nonlinear seepage parameters as well as external loads on consolidation behavior. Results indicate that, when the compression index (I_c) remains constant, greater permeability parameters lead to slower soil consolidation. Similarly, when the permeability parameter is constant, a larger compression index results in slower soil consolidation. Additionally, higher external loads (q_u) correspond to greater settlement of the soil layer, faster dissipation of excess pore water pressure, and accelerated consolidation rate. To conclude, a differential analysis of large-strain consolidation theory versus small-strain consolidation theory reveals the inapplicability of the latter in the presence of significant soil strain. Instead, the large-strain consolidation theory should be employed for accurate calculations.

Key words: soft soil, bilogarithmic model, large-strain consolidation, Non-Darcy flow, finite difference method