Construction Materials Questions and Answers - Cofferdam and Caisson

1. Identify the given pile driving formula.
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a) Merriman formula
b) Ritter formula
c) Vulcan Iron Works formula
d) Kreutzer formula

Answer: b
Explanation: Above given formula is Ritter formula. It is an important pile driving dynamic formula. Where, R = ultimate load carrying capacity of pile in kg.
H = height of free fall of ram in case of drop hammer in cm.
S = final settlement of pile in cm.

2. Identify the given pile driving formula.
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a) Merriman formula
b) Ritter formula
c) Kreutzer formula
d) Dutch formula

Answer: a
Explanation: Merriman formula is same as the Major Sander formula except that a factor of safety of 6 is used. It is one of the most important pile-driving dynamic formulas.

3. A _______ is defined as a temporary structure which is constructed so as to remove water and/or soil from an area and make it possible to carry on the construction work under reasonably dry conditions.
a) Cofferdam
b) Foundation
c) Caisson
d) Spillway

Answer: a
Explanation: The cofferdam is generally constructed at the site of work. The cofferdam should be reasonably watertight. It may either raised on the impervious soil or may be extended to impervious strata through pervious soils. It should be noted that absolute water tightness is not desired in a cofferdam

4.A _________ is an embankment of some material.
a) Wall
b) Intrusion
c) Dike
d) Rock-fill

Answer: c
Explanation: The materials commonly employed for the construction of dike are earth, rock and sand bags. The dike are generally employed for a short duration, particularly to enable the construction of a more durable cofferdam behind them.

5. __________ is the simplest form of cofferdam.
a) Single wall cofferdam
b) Earth-fill cofferdam
c) Cellular cofferdam
d) Rock-fill cofferdam

Answer: b
Explanation: Earth dikes or Earth-fill cofferdams are limited to Shallow depth of water, say about 1200 mm to 1500 mm, with a low velocity of flow. It consists of an Earth bank which is placed around the site to be enclosed.

6. ________ type of cofferdam is economical at places where rock is available in plenty.
a) Earth dikes
b) Sand-bags dikes
c) Rock-fill cofferdam
d) Single wall cofferdam

Answer: c
Explanation: Rock dikes or Rock-fill cofferdams can be used for a depth of water up to about 3 metres and a suitable even in case of Swift water. The only disadvantage of this type of cofferdam is that it is not impervious.

7. In __________ type of cofferdam consists of a mixture of sand and clay which is filled in a bag and placed instead of earth or rock to form a cofferdam.
a) Cellular cofferdam
b) Earth dikes
c) Rock dikes
d) Sand-bag dikes

Answer: d
Explanation: The sand-bag dykes or Sand-bag cofferdams are useful for small depth of water. The individual bags are laid in courses as in case of masonry work and the joints are filled with puddle.

8. __________ it suitable when available working space is limited and the area to be enclosed is small.
a) Single wall cofferdam
b) Double wall cofferdam
c) Dikes
d) Concrete cofferdam

Answer: a
Explanation: Single wall cofferdams is suitable up to a maximum depth of water of 25 m. In this type of cofferdam, a single row of Piles is used on either side of the cofferdam. The sheet pile maybe of wood or steel. The wooden piles are generally used for depth of water up to about 10 m.

9. When the area to be enclosed is large, it becomes essential to provide the _________ construction so as to give stability to the cofferdam.
a) Single wall cofferdam
b) Cellular cofferdam
c) Double wall cofferdam
d) Suspended cofferdam

Answer: c
Explanation: Double wall cofferdam was frequently used on the river Ohio in USA and hence, it derives its name as Ohio river type cofferdam. It is cheap and can be built up rapidly l. It is suitable for hard bed where there is no problem of erosion. This type of cofferdam is unsuitable for deep water.

10. __________ is useful when depth of water is about 6 metres to 10 meters.
a) Wood or steel sheeting cofferdam
b) Ohio river type cofferdam
c) Rock-filled crib cofferdam
d) Suspended cofferdam

Answer: a
Explanation: For small and ordinary type of cofferdam, the wooden sheet piles are employed. But when cofferdams are large or where it is not possible to drive guide piles due to more depth of water, the steel sheet piles with suitable bracing are used for the construction of this type of cofferdam.