Bearing Capacity of Soil MCQ with answer and solution

Concept

For a purely cohesive soil (φ = 0), Terzaghi gives N_c = 5.7, N_q = 1 and N_γ = 0.

Formula

For φ = 0 (Terzaghi): N_c = 5.7, N_q = 1, N_γ = 0; so N_c/N_q = 5.7

Step-by-step solution

1. A purely cohesive soil means φ = 0. 2. Terzaghi factors at φ = 0: N_c = 5.7, N_q = 1.0. 3. Ratio N_c/N_q = 5.7/1 = 5.7. 4. So the answer is (B).

Explanation

For a clay with φ = 0, Terzaghi's theory gives N_c = 5.7 and N_q = 1. So the ratio N_c/N_q = 5.7. The value 5.14 belongs to the Prandtl/Skempton theory, not Terzaghi.

Why the other options are wrong

A: 5.14 is N_c from Prandtl/Skempton theory (π + 2), not Terzaghi. C: 2.85 is half of 5.7, which has no meaning here. D: 2.57 is half of 5.14, which also has no meaning here.

Shortcut

For φ = 0, N_q = 1, so N_c/N_q = N_c = 5.7 (Terzaghi).

Common mistake

Choosing 5.14 (Prandtl/IS value) when the question asks for Terzaghi factors.