Piecewise-Linear Model for Large-Strain Consolidation with Threshold Hydraulic Gradient

Abstract

Experimental studies found that water flow in clay might not obey Darcy’s law. In some fine-grained soils, the water flow could occur only when the threshold gradient was exceeded. This study investigates the effects of threshold gradient on the consolidation profile. The well-established model CNDF2 is employed with some modifications. Verification examples demonstrate the accuracy of the numerical simulation in this study. Compared with the existing solution in the literature, modeling results in this study are more reliable because the criterion of seepage is independent of the position of the seepage front. Parametric studies find that the excess pore-water pressure cannot be fully dissipated if there is a threshold gradient. A larger value of normalized threshold hydraulic gradient R will result in a larger value of residual excess pore-water pressure. A permeable bottom boundary can contribute to the dissipation of residual excess pore-water pressure. The final settlement will also be affected by the threshold hydraulic gradient. A larger value of R will lead to a smaller final settlement due to the residual excess pore-water pressure. The average degree of consolidation will not be affected by the threshold hydraulic gradient.