Shallow Foundations MCQ with answer and solution

Concept

Minimum foundation depth requirements for shallow foundations to protect against seasonal volume changes and weathering.

Step-by-step solution

Step 1: Refer to IS 1904 specifications regarding the minimum depth of shallow foundations. Step 2: Identify the specified minimum depth below natural ground level for normal soils, which is 50 cm (0.5 m). Step 3: Note exceptions such as solid rock where this depth may not be required.

Explanation

According to IS: 1904 (Code of practice for design and construction of foundations in soils: general requirements), all foundations shall extend below natural ground level to a minimum depth of 50 cm, except when erected on rock or weather-resisting natural ground.

Why the other options are wrong

A: 15 cm is too shallow and susceptible to surface disturbance. C: 1 m is generally used for specific poor soils or frost conditions, not the minimum absolute standard. D: 2 m is excessively deep for a minimum general requirement.

Shortcut

Remember that 50 cm is the standard minimum depth for shallow foundations in building codes (like IS 1904) to avoid topsoil and weathering effects.

Common mistake

Confusing minimum foundation depth (50 cm) with standard depth for frost heave or specific soil conditions which can be much higher.