Strength of Materials Questions and Answers – Rectangular Dam

This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Rectangular Dam”.

1. Which of the following is not a failure of a rectangular dam?
a) Overturning
b) Toe erosion
c) Sliding
d) Foundation failure
View Answer

Answer: b
Explanation: Among the above failures, the toe erosion is not related to rectangular dams. Toe erosion is caused due to in some cases the spillway is constructed very near to the dam section inside circumstances the discharge water may erode the dam.

2. Structural failures contribute about _______________ in the failure of dam.
a) 45%
b) 60%
c) 30%
d) 20%
View Answer

Answer: c
Explanation: About 30% of failures are due to:
i. Foundation slide
ii. Upstream slope failure
iii. Downstream slope failure
iv. Failure due to flow slide.

3. The free board is provided in dams to avoid _______________
a) Piping
b) Foundation of upstream
c) Wave erosion
d) Overtopping
View Answer

Answer: d
Explanation: By providing sufficient free board and by providing an adequate capacity of the spillway, failure due to overtopping of the damn can be avoided.

4. By providing ______________ gully formation can be avoided.
a) Berms
b) Aqueduct
c) Spillway
d) Free board
View Answer

Answer: a
Explanation: By providing berms and turning on the downstream face of the dam, the failure due to the formation of the gullies can be avoided.

5. The maintenance of the reservoirs, above _____________ Ha comes under irrigation department.
a) 30
b) 40
c) 50
d) 60
View Answer

Answer: b
Explanation: The maintenance of reservoirs is having commendable area below 40Ha comes under Panchayat Raj department and above 40 Ha come under irrigation department.
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6. Which of the following process will you prefer to prevent the leakage of water in the dam foundation?
a) Guniting
b) Grouting
c) Gam mixing
d) Filling
View Answer

Answer: b
Explanation: Grouting is a process in which a grout in liquid (8:1) slurry form, is injected into the soil under suitable pressures and applied through the pipes.

7. ______ grouting increases the bearing capacity of soil.
a) Curtain
b) Consolidated
c) Blanket
d) Descending stage grouting
View Answer

Answer: b
Explanation: According to functions served, the groutings can be classified into
i. Consolidated grouting
ii. Curtain grouting
iii. Area grouting
Consolidation grouting increases the bearing capacity of the soil and creates proper bonding between separated bodies.

8. According to IS, the specific gravity of a good building stone used in heavy dams should be ______
a) 2.2 – 2.4
b) 2.3 – 2.5
c) 2.4 – 2.8
d) 2.6 – 3
View Answer

Answer: c
Explanation: The stones used for heavy irrigation works such as dams, bridges, check dams, weirs, docks should have specific gravity between 2.4 to 2.8. Stones used for the roof may have less specific gravity.

9. Hardness can be measured using _______
a) Mohr’s scale
b) Silica scale
c) Dalton’s scale
d) Abrasion factor
View Answer

Answer: a
Explanation: The property to resist the abrasive forces cause due to wear & tear and friction is called hardness. It is determined by the Mohr’s scale of hardness in a laboratory. A hard stone will not show any scratches.

10. Granite has been widely used for dams construction because of _______
a) Crushing strength
b) Cost
c) Workability
d) Porosity
View Answer

Answer: a
Explanation: Granite stone is derived from igneous rocks. It is very hard, durable and strong. Its crushing strength is 100 to 140 N/mm^2. For this property, it is widely used in all important works.

11. The range of slenderness ratio in dams varies from ________
a) 13 – 15
b) 12 – 15
c) 15 – 18
d) 15 – 20
View Answer

Answer: b
Explanation: In dams, the slenderness ratio can be calculated through
= Height of buttress / Thickness of buttress
• It varies from 12 to 15.

12. _______ is provided for installation of control equipment of valves in dams.
a) Vertical shafts
b) Hydraulic openings
c) Connecting passages
d) Isolated chambers
View Answer

Answer: d
Explanation: Isolated chambers are provided for installation of control equipment of walls or pipeline or pumps. The function is to supply water to irrigation canals, fulfilling commitments and desilting the reservoir.

13. The ratio of the volume of voids to the volume of given soil mass is __________
a) Porosity
b) Void ratio
c) Dry density
d) Specific gravity
View Answer

Answer: a
Explanation: The porosity of a given soil sample is the ratio of the volume of voids to the value of given soil mass. It is denoted by “n”.
n = Vu / V.

14. Sand layer is an example of ______________
a) Aquiclude
b) Aquifuge
c) Aquitard
d) Aquifer
View Answer

Answer: d
Explanation: An aquifer is a geologic formation (or) saturated bed which contains water and yields them significantly. Example: sand bed. They permit the appreciable quantity of water under ordinary field conditions.

15. ________ keeps the phreatic line within the dam section.
a) Longitudinal filter
b) Cross filter
c) Rock toe
d) Toe drain
View Answer

Answer: c
Explanation: Rock toe keeps the phreatic line within the damn section and also facilitates drainage. It is nothing but a downstream portion of a dam made of graded material. To achieve good results, the height of rock toe shall be kept 1/3 to 1/ 4 of dam height.

Sanfoundry Global Education & Learning Series – Strength of Materials.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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