Water movement associated with overburden potential in a shrinking marine clay soil

In unripe marine clay soils, water flow occurs in relation to shrinkage and swelling of the soil material. In the initial stage of physical ripening, when the soil retains its higher moisture ratio, dewatering is mainly accompanied by normal and unidimensional shrinkage. Soilwater flow at this stage, in the absence of significant mateic potential differences, can be explained only by overburden potential. In a one-dimensional vertical system, numerical solutions of non-steady flow during normal shrinkage have been validated with experimental data. For the condition of a closed boundary at the top and a constant pressure head at the bottom, there are significant differences in downward flux density with and without an overburden component to total potential. Further, for the condition of a closed bottom boundary, the generation of an upward flux can only be attributed to the overburden potential. This implies that the overburden potential plays an important role in the Darcy flow, especially for the unripe marine clay soil.