This set of Strength of Materials Multiple Choice Questions on “Dams”.
1. The obstruction or a barrier built across the stream or river is called _____________
a) Barrage
b) Weir
c) Dam
d) Reservoir
Answer: c
Clarification: A dam may be defined as an obstruction or a barrier built across the stream or river these are artificial storage works. It retains water to create an impounding reservoir.
2. FTL Stands for ________
a) Free tank level
b) Full tank level
c) Full top level
d) Fill toe level
Answer: b
Clarification: It is also called a full reservoir level (FRL). It is a level up to which the water stored obviously the crest of the spillway is fixed at this level.
3. _______ is openings extending from upstream to downstream of the dam.
a) Guide banks
b) Divide voids
c) Sluices
d) Spillway
Answer: c
Clarification: Sluices are openings or conduits extending from upstream face of the dam to downstream face of the dam. They are used to clean the silt from the reservoir. They also decrease the peak flood in the reservoir.
4. Water stored in dam is expressed in _______
a) Mega cumec metres
b) Million cubic metres
c) Metric cumec
d) Million cusec metres
Answer: b
Clarification: It is the total quantity of water stored up to FRL. It includes dead storage also. It is expressed generally in thousand hectare metre or million cubic metres (Mm3).
5. MDDL Stands for ________
a) Minimum draw down level
b) Maximum draw down level
c) Million drop down level
d) Mega drop down level
Answer: a
Clarification: It is the lowest level up to which the reservoir is depleted from the considerations of hydropower generation. So this level is known as minimum draw down level (MDDL).
6. _____ dam which resists are the external forces by virtue of its self weight.
a) Earthen dam
b) Storage dam
c) Detention dam
d) Gravity dam
Answer: d
Clarification: A gravity dam is that, which is stable against all the external forces achieved by the weight of the dam itself. This is the most permanent one and hence it is very commonly used. It may be constructed in all localities.
7. The factor of safety against overturning should not be less than ______
a) 1.8
b) 2.25
c) 1.5
d) 1.75
Answer: c
Clarification: In the dam section, the overturning takes place when a resultant force cuts the base of the dam downstream of the toe. The factor of safety against overturning is the ratio of the stabilizing moment to the overturning moments. The safety against overturning should not be less than 1.5.
8. In sliding failure, the co-efficient of friction varies from ________
a) 0.65 – 0.75
b) 0.8 – 0.9
c) 0.45 – 0.65
d) 0.85 – 1
Answer: a
Clarification: To avoid sliding, the factor of safety against the sliding should be greater than 1.
F.S = M(V-U) / €H > 1
Where M = Co-efficient of friction. It varies from 0.65 to 0.75
V = Total vertical force
U = Upward force.
9. Which of the following forces do not act on the dam?
a) Silt pressure
b) Wave pressure
c) Creep pressure
d) Uplift