Shallow Foundations MCQ with answer and solution

Concept

The type of foundation is chosen based on the loads, the soil type and strength, and the water table position. It is not chosen based on compaction properties like OMC.

Step-by-step solution

1. List the factors that control the choice of foundation: magnitude and type of loads, type of soil and its bearing capacity, depth of the ground water table, and allowable settlement. 2. Check each option against this list. 3. Magnitude of loads: affects the choice (heavy loads may need a raft or piles). 4. Type of soil: affects the choice (weak soil may need deep foundations). 5. Depth of ground water table: affects the choice (a high water table reduces bearing capacity). 6. OMC: this is a compaction property used for fills and embankments, not for selecting a foundation type. 7. So the answer is (C).

Explanation

Foundation type depends on how heavy the load is, how strong the soil is, and where the water table is. OMC is the water content that gives maximum dry density in a compaction test. It is used for controlling compaction, not for selecting the foundation type.

Why the other options are wrong

A: Load magnitude decides whether isolated footings, a raft or piles are needed. B: Soil type decides the bearing capacity and settlement, so it directly affects the choice. D: A high water table reduces bearing capacity and causes construction problems, so it affects the choice.

Shortcut

OMC belongs to compaction (roads, embankments), not to foundation selection.

Common mistake

Thinking that every soil property affects the foundation choice. OMC is only a compaction parameter.