A Cofferdam is a temporary structure built primarily to
- AAct as a permanent foundation for a bridge pier.
- BProvide housing for the construction workers.
- CIncrease the velocity of the river flow.
- DExclude water from an area to allow construction to be performed in the dry.Correct
Solution
Concept
Cofferdams
Formula
N/A
Step-by-step solution
1. Understand the function of a cofferdam in foundation engineering. 2. Recall that a cofferdam is a temporary watertight structure designed to exclude water so construction can happen in a dry area. 3. Compare with the given options and select Option (d) as the correct choice.
Explanation
A cofferdam is a temporary watertight structure built in or around a body of water. Its main purpose is to pump water out of an area and keep it dry so that workers can safely construct foundations, bridge piers, or other structures on dry ground.
Shortcut
To remember the primary purpose of a Cofferdam, use the mnemonic "COFFER = Cover & Keep Dry": - Coffer: Think of a "Coffin" or "Box" placed in water to exclude/seal out water. - Keep Dry: Creates a temporary dry environment so workers can build underwater foundations.
Common mistake
A common mistake is selecting Option A by confusing a cofferdam with a permanent foundation element, like a caisson or pier. Students often forget that a cofferdam is strictly a temporary enclosure that is removed once the permanent structure is built in dry conditions.
Correct answer: D) Exclude water from an area to allow construction to be performed in the dry.