Which of the following statements regarding Terzaghi's Bearing Capacity Theory is INCORRECT?

Explanation:

Terzaghi's Bearing Capacity Theory:

Bearing capacity of soil: 

Where,

C = Cohesion, Df = Depth of footing, B = Width of footing, γ = unit weight of footing, Nc, Nq, Nγ = Bearing capacity factors

Assumptions:

1. The soil is homogeneous and isotropic and its shear strength is represented by Coulomb's equation.
2. The strip footing has a rough base, and the problem is essentially two-dimensional.
3. The elastic zone has straight boundaries inclined at ψ = ϕ to the horizontal, and the plastic zones fully develop.,
4. Pp consists of three components, which can be calculated separately and added, although the critical surface for these components is not identical.
5. Failure zones do not extend above the horizontal plane through the base of the footing, i.e. the shear resistance of soil above the base is neglected and the effect of soil around the footing is considered equivalent to a surcharge σ = γ × D [γ = unit weight of soil, D = Depth of foundation.
6. The ground surface is horizontal.
7. The failure is studied as a general shear failure.
8. The load acting on the footing is vertical and symmetrical.

Additional Information

Limitation: 

1. As the soil compresses, ϕ (angle of internal friction) changes; slight downward movement of footing does not develop fully plastic zones.
2. Error due to assumption 4 is small and on the safe side
3. Error due to assumption 5 increases with the increase with depth of foundation, hence the theory is suitable for shallow foundations only.