# Terzaghi’s Theory of One-Dimensional Consolidation

1. The theory for the time rate of one-dimensional consolidation was initially planned by Terzaghi (1925). The underlying assumption in the derivation of the mathematical equations are as follows
2.  The soil is homogeneous and isotropic.
3.  The soil is fully saturated.
4. The solid particles and water within the voids are incompressible. The consolidation happens because of the expulsion of water from the voids.
5. The coefficient of permeability of the soil has the same value at all points and it remains constant during the entire period of consolidation.
6. Darcy’s law is valid throughout the consolidation process.
7. Soil is laterally confined, and the consolidation takes place only in the axial direction. Drainage of water also occurs only in the vertical direction.
8. The interruption in consolidation is due entirely to the low permeability of the soil.
9. There is unique. relationship between the void ratio and therefore the effective stress and this relationship remains constant throughout the load increment. In alternative words, the constant of squeezability and therefore the constant of volume change area unit constant.
10. The assumptions made by Terzaghi’s are not fully satisfied with actual field problems. The results obtained from the use of the theory to practice problems are approximate. However, considering the complexity of the problem, the theory gives a reasonably accurate estimate of the time ratio of the settlement of a structure built on the soil.