Abstract: Natural soil layers typically demonstrate nonlinear compression characteristics and often exist in varying consolidation states during their formation, with the consolidation laws of soil differing under these distinct states. This study takes into comprehensive account the variations in void ratio and permeability coefficient during the soil consolidation process, along with the influence of linear loading, to formulate a one-dimensional consolidation equation for overconsolidated cohesive soil that incorporates these variations. To validate the accuracy and applicability of the proposed theory, a series of joint tests of one-dimensional consolidation and infiltration during consolidation were carried out on the silty cohesive loess in Xi’an, Shaanxi Province, using a GDS advanced consolidator. Following this, the finite difference method was applied to derive the finite difference equation corresponding to the one-dimensional consolidation equation for overconsolidated soils. The consolidation equation was solved by using MATLAB programming, yielding finite difference solutions for pore water pressure, settlement, and the degree of consolidation during the one-dimensional consolidation process. A comparative analysis was conducted between the finite difference solutions, the results from the one-dimensional consolidation-permeability coupled tests, and the solutions derived from Terzaghi's consolidation theory. The findings reveal that the consolidation theory, which accounts for variations in void ratio and permeability coefficient during consolidation, yields results that closely align with measured values and are more congruent with practical engineering scenarios. Additionally, under varying preconsolidation stresses, the consolidation rate, when considering the nonlinear characteristics during soil consolidation, is slower compared to that predicted by Terzaghi’s theory; however, the ultimate soil settlement calculated by both approaches remains largely consistent.

Key words: over-consolidated cohesive soil, void ratio, permeability coefficient, finite difference solution, consolidation behavior