The value of the coefficient of consolidation has been assumed to be constant.

The distance d of the drainage path cannot be measured accurately in the field. The thickness of the deposit is generally variable, and an average value has to be estimated.

There is sometimes difficulty 1n locating the drainage face, sometimes thin previous seams that can act as good drainage face are missed in the boring operations.

The equation is based on the assumption that the consolidation is one-dimensional. In the field, the consolidation is generally 3-dimensional. The lateral drainage may have a significant effect on the time rate of consolidation.

The initial consolidation and secondary consolidation have been neglected. Sometimes these form an important part of the total consolidation.

In actual practice, the pressure distribution may be far from linear or uniform