Permeability of structural soft soils

The permeability characteristics of natural soft clays and corresponding remolded clays were investigated in laboratory. The coefficient of permeability of soft clays changes little at the early loading and changes sharply during loading beyond the structural yielding stress. The relationship between void ratio and logarithm of permeability is almost the same before and beyond the structural yielding stress, indicating that the effect of bonding on the permeability is small. The change in the permeability of remolded clays is relatively small. At the same void ratio, the permeability of undisturbed soil is greater than that of the corresponding remolded clay. This is due to different fabrics, i.e., undisturbed soil is different from remolded soil in the macropore between large particle and the floccules and in the formation of soil particle alignment in the history. The coefficient of permeability is almost the same for remolded soils with the same remolding method and different initial water contents. Even if void ratio is the same, the coefficient of permeability is different due to different ways of remolding. Void ratio and fabric are necessarily considered for determining the coefficient of permeability of clays.