Settlement of Foundations MCQ with answer and solution

Concept

Maximum permissible differential settlement on clayey soil

Formula

NONE

Step-by-step solution

1. According to IS 1904, maximum permissible differential settlement depends on the soil type and foundation structure. 2. For isolated foundations on clayey soil, the maximum permissible differential settlement is restricted to 40 mm. 3. For raft foundations on clayey soil, permissible differential settlement ranges from 40 mm to 65 mm depending on rigidity, but the standard value specified for isolated footings on clay is 40 mm. Answer: D

Explanation

According to IS 1904, the maximum permissible differential settlement for isolated foundations on clayey soil is limited to 40 mm. Clay soils undergo slow and non-uniform consolidation settlement, which increases the risk of structural cracking under differential movement. Adhering to this limit ensures that structural distortion remains within safe serviceability tolerances.

Why the other options are wrong

A) 50 mm is the maximum permissible differential settlement for isolated footings on sand. B) 60 mm is not a standard IS 1904 permissible settlement value. C) 65 mm is the maximum permissible total settlement for isolated footings on clay.

Shortcut

Differential settlement limit: Clay is strictly limited to 40 mm.

Common mistake

Confusing maximum permissible differential settlement with maximum total permissible settlement for isolated footings on clayey soil.