Irrigation Engineering Mcqs


What is suggested massiveness factor for simply supported RCC Decks?

A) 2.5 to 3 B) 3 to 4.5
C) 4.5 to 7.5 D) 7.5 to 12
Answer & Explanation Answer: A) 2.5 to 3

Explanation: Massiveness factor and slenderness ratio both controls the height, thickness and the spacing of the buttress. The suggested slenderness ratio usually ranges from 12 to 15 and the massiveness factor varies from 2.5 to 3.

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What is the suggested slenderness ratio for simply supported RCC decks?

A) 4.5 to 7.5 B) 7.5 to 12
C) 12 to 15 D) 15 to 18
Answer & Explanation Answer: C) 12 to 15

Explanation: The height, thickness and spacing of buttresses can be controlled by Slenderness ratio. Slenderness ratio is the ratio of the height of the buttress to the thickness of the buttress. The value usually ranges from 12 to 15.

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What is the suggested economic buttress spacing for a mean dam height of greater than 45 m?

A) 4.5 B) 4.5 to 7.5
C) 7.5 to 12 D) 12 to 15
Answer & Explanation Answer: D) 12 to 15

Explanation: Not available for this question

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The buttresses of a free deck buttress dam are provided at ‘x’ m clear spacing and buttress thickness is proposed to be ‘t’ m. The buttress section can then be designed like the section of a concrete gravity dam by considering the effective unit weight of water = Surcharge factor (S) x actual unit weight of water. The value of this surcharge factor is given as _____________

A) S = (x + t)/x B) S = (x + t)/t
C) S = (x + t)/(x + 1) D) S = (x + t)/(t + 1)
Answer & Explanation Answer: B) S = (x + t)/t

Explanation: Surcharge factor (S) is the ratio of the dam length (x + t) to the buttress thickness (t).
S = (x + t)/t
The resultant impact can be considered by increasing the unit weight of water by multiplying the actual value by a surcharge factor.

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In a simple deck slab buttress dam of a given height, the buttress spacing can be increased by increasing the upstream slope.

A) True B) False
Answer & Explanation Answer: A) True

Explanation: The economical spacing of buttresses is governed to a very large extent by the values of the upstream slope of the dam which is given by the master curve. The lower values of upstream slope lesser than 47° are not available on the master curve which shows that lower values will not prove economical for the project.

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Which of the following is the earliest recorded multiple arch buttress dam?

A) Meer Alam dam in India B) The Coolidge dam in Arizona
C) Rodriguez dam in Mexico D) Idduki dam in Kerela, India
Answer & Explanation Answer: A) Meer Alam dam in India

Explanation: The Coolidge dam on San Carlos River in Arizona is a multiple dome-type dam having a height of 76.2 m with buttresses @ 54.8 m apart. The Rodriguez dam in Mexico is the highest deck slab type dam having a height of 73.2 m. The Idduki dam is a concrete double curvature parabolic thin arch dam.

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Which of the following type of dam requires very strong and stable foundations and is not in use as much as the other types?

A) Multiple dome-type dams B) Massive head type dam
C) Columnar buttress type dam D) Deck slab type dam
Answer & Explanation Answer: C) Columnar buttress type dam

Explanation: Columnar buttress type dam is a modification of the ordinary slab type and the deck is supported on columns. It requires a very durable base and more skill is required in constructing the buttresses.

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Which of the following component of a buttress dam is also called counterfort?

A) Corbel B) Buttress
C) Lateral brace D) Sloping deck
Answer & Explanation Answer: B) Buttress

Explanation: A counterfort or a buttress is a structure built against the wall to prevent overturning or to increase its bending strength. This term is synonymous with the buttress and is often used when referring to the dam, retaining walls and other structures.

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