The following Four statements (S1, S2, S3, S4) in connection with soil behaviour are given. S1: Consolidation is a function of total stress S2: Permeability of Coarse grained soil is inversely proportional to the specific surface at a given porosity. S3: For a fully saturated soil the pore pressure parameter is equal to zero. S4 : Terzaghi's theory of consolidation considers only primary consolidation. Which of the above statement(s) is /are incorrect?

Option 3 : S1 and S3

Concepts:

S1: False

The expulsion of pore water by applying a steady load for a long time from a fully saturated soil sample is called Primary Consolidation or simply consolidation.  It is completed when all the excess pore water gets expelled from the soil and it is time taking phenomenon.

As per Terzaghi's one-dimensional theory of consolidation, primary consolidation is a function of effective stress only and it is independent of total stress.

S2: True

The higher the specific surface area, the higher will be the friction so water will not flow easily, and hence, low will be permeability. Therefore, the Permeability of Coarse-grained or even fine-grained soil is inversely proportional to the specific surface area at a given porosity.

S3: False

Skempton's Pore Pressure coefficients are A and B, Where A depends upon the degree of saturation and over consolidation ratio and B depends upon the degree of saturation of the soil.

In general, A < 1 and B < 1. However, for over-consolidated soil the value of A < 0 and for fully saturated soil, the value of B is 1.

 S4: True

Terzaghi's one-dimensional theory of consolidation considered only primary consolidation. Even after complete dissipation of excess pore pressure, the soil undergoes a little more consolidation due to plastic rearrangement of soil solids which is called secondary consolidation.