Question

Match List 1 and List 2 and select the correct answer using the codes given below:

List-1	List-2
A. Cut-off trench of a dam to be constructed across the flowing river	1. Cellular sheetpile cofferdam
B. Shallow foundation of a bridge pier foundation work	2. Embankment type cofferdam
C. Sequential repetition of underwater foundation work	3. Single wall sheetpile cofferdam
D. Control of groundwater to prevent entry into a deep excavation	4. Floating steel cylinder cofferdam

1. A – 4, B – 3, C – 2, D - 1
2. A – 2, B – 1, C – 4, D - 3
3. A – 2, B – 3, C – 1, D - 4
4. A – 3, B – 4, C – 2, D - 1

Answer 1

Correct Answer - Option 2 : A – 2, B – 1, C – 4, D - 3

Concept:

Cofferdam:

• Cofferdams are built within the water body to allow the enclosed area to be pumped out.
• These are usually used for the construction or repair of permanent dams, bridge piers, etc built within the water body.
• The following table shows the different types of cofferdams and their properties:
   

Type	Characteristics
1. Single-walled cofferdam	These are preferred when the depth of water is more than 6 m and the construction area is less. These are used in the construction of bridges to prevent the entry of groundwater into the deep excavation.
2. Double-walled cofferdam	These are preferred when the construction area is more and depth higher. These can hold water up to 12m in height.
3. Embankment type cofferdam	The height of such dams is kept 1m more than the maximum water level. These are constructed across the flowing river.
4. Cellular sheet pile cofferdam	These are preferred when the water layer is more than 20m. These are used in the construction of the foundation of bridge piers.
5. Floating steel cylinder cofferdam	These are preferred for sequential repetition of underwater foundation work.