Cofferdams MCQ with answer and solution

Concept

Height limits of different cofferdam types

Formula

NONE

Step-by-step solution

1. Cofferdams are temporary structures constructed to exclude water from an excavation area. 2. A single-walled cofferdam consists of a single row of sheet piles braced internally and is suitable for moderate water heads up to around 12 m. 3. Therefore, single-walled cofferdam is the correct answer. Answer: D

Explanation

A double-walled cofferdam consists of two parallel rows of sheet piling filled with soil or gravel to provide stability against water pressure. This robust construction enables it to safely hold water heads up to 12 meters, whereas earthen or single-walled cofferdams are limited to lower heights. Therefore, option D is correct.

Why the other options are wrong

A) Earthen cofferdams are suitable for holding water up to depths of 3 meters. B) Rockfill cofferdams are designed for water heights up to 10 meters.

Shortcut

Double-walled cofferdams are designed for deep water up to 12 m height.

Common mistake

Selecting Rockfill or Single-walled cofferdam by misremembering the maximum height limits for cofferdam types.