The _______ is made of steel sheet piles and this type of cofferdam is proved successful in unwatering large areas.
- ASuspended cofferdam
- BCellular cofferdamCorrect
- CDikes
- DConcrete cofferdam
Solution
Concept
Characteristics of cellular cofferdams
Formula
NONE
Step-by-step solution
1. A cellular cofferdam consists of interlocked steel sheet piles driven to form a series of enclosed cells filled with soil or gravel. 2. This self-supporting, gravity-type retaining structure provides high lateral resistance against water pressure. 3. It is widely and successfully used for unwatering large, deep water bodies or riverbeds for construction. Answer: B
Explanation
A cellular cofferdam is constructed by driving interlocking steel sheet piles into self-supporting circular or diaphragm cells filled with soil or gravel. This massive structure provides high stability against overturning and water pressure, making it ideal for dewatering large areas. Therefore, cellular cofferdams are widely used for major marine and river construction projects.
Why the other options are wrong
A) Suspended cofferdams are light structures used in shallow waters, not steel sheet pile enclosures for large areas. C) Dikes are earth embankments rather than steel sheet pile structures. D) Concrete cofferdams are constructed using concrete walls, not steel sheet piles.
Shortcut
Steel sheet piles formed into cells = Cellular cofferdam.
Common mistake
Confusing cellular steel sheet pile cofferdams with earthen dikes or concrete cofferdams used in different site conditions.
Correct answer: B) Cellular cofferdam