One-dimensional large-strain nonlinear consolidation analysis under ramp load with Swartzendruber’s flow and time-dependent drainage boundary

To address challenges in semi-logarithmic compression and permeability relations for simulating large-strain deformation, an improved one-dimensional (1D) nonlinear consolidation model for soft clayey soil under variable load is developed using a bi-logarithmic compression and permeability model. The developed consolidation system incorporates Swartzendruber’s flow and time-dependent drainage boundary (TDB) conditions to capture non-Darcy flow (NDF) effects and limited drainage capacity. The finite difference solution is validated against analytical solutions and lab experiments. Results show that higher compression or permeability indexes reduce consolidation rate, while final settlement depends on the compression index. A comparative analysis using the large and small strain consolidation theories revealed that when the soil strain reaches about 15%, the calculated settlement can differ by about 7%. Therefore, when the soil strain reaches or exceeds 15%, it is necessary to use the large-strain consolidation theory to carry out soil consolidation calculations.