Abstract: The analytical solution for the nonlinear large strain consolidation model is significant for the actual engineering. However, since the large-strain consolidation theory of saturated soft soil involves complex material nonlinearity and geometrical nonlinearity problems, it is usually challenging to obtain an analytical solution for the large strain consolidation models. At present, the nonlinear compression and permeability characteristics of soils are usually described by e- and e- (e is the void ratio, is the effective stress, and is the permeability coefficient). However, large numbers of laboratory consolidation tests show that those nonlinear relationships are no longer suitable for the high compressibility soft soil with large strain. In contrast, the nonlinear relationships between the void ratio and effective stress as well as the void ratio and permeability coefficient of soft soil with high compressibility can be described by - and - more effectively. Therefore, in this study the one-dimensional nonlinear large strain consolidation model of the high compressible soft soil under a ramp loading is developed, and the exact analytical solution with the specific parameters and the approximate solutions under the general conditions are developed. The reliability of the proposed analytical solutions is validated by comparing the calculated settlement curve with the experimental settlement curve under a ramp loading in the laboratory. On this basis, the influences of parameters ( and ), external load, and loading rate on the consolidation behavior are investigated by numerous calculations. The results show that at a certain compression index , the smaller the , the faster the consolidation rate of the soil layer, and the faster the dissipation of the excess pore-water pressure at the bottom of the clay layer. Conversely, as is constant, the smaller the , the faster the consolidation rate of the soil layer, and the faster the dissipation of the excess pore-water pressure at the bottom of the clay layer. The average degree of consolidation in terms of settlement is generally larger than that of the consolidation accounting for the excess pore-water pressure , which means the development rate of settlement is faster than pore pressure dissipation. In addition, when ( 2) 1, the average consolidation rate decreases with the final external load increasing. When ( 2) 1, the average consolidation rate increases with the final external load increasing. When ( 2) 1, the average consolidation rate is independent of the final external load. Moreover, when the final external load is constant and the loading rate increases, the average consolidation rate increases while the excess pore-water pressure at the same depth decreases.

Key words: high compressible soil, nonlinearity, large-strain, time-dependent loading, analytical solution