Bearing Capacity of Soil MCQ with answer and solution

Concept

Ultimate bearing capacity is the minimum gross pressure at the base of a foundation at which the soil fails in shear.

Formula

q_nu = q_u - γD_f

Step-by-step solution

1. Gross ultimate bearing capacity q_u is the minimum gross pressure at the footing base that causes shear failure. 2. Net ultimate bearing capacity q_nu = q_u - γD_f is the net pressure that causes failure. 3. The question asks for ultimate bearing capacity, so the gross definition fits. Option B.

Explanation

Ultimate bearing capacity is the least gross pressure at the base of a footing that makes the soil fail in shear. If we subtract the overburden pressure γD_f, we get the net ultimate bearing capacity. So option B is the correct definition.

Why the other options are wrong

A: This is the net ultimate bearing capacity, not the (gross) ultimate bearing capacity. C: This describes net pressure intensity, not failure pressure. D: This is the gross pressure intensity from the load, not the capacity of the soil.

Shortcut

Ultimate = gross + failure; Net ultimate = gross - γD_f.

Common mistake

Choosing the net definition (A) for ultimate bearing capacity.