This set of Strength of Materials Questions and Answers for Campus interviews on “Trapezoidal Dam as Inclined Side Phase”.
1. Calculate the eccentricity of a trapezoidal dam with a distance between the centre of gravity and point where the resultant cuts the base is 5m. The bottom width of the dam is 3m.
a) 2.5m
b) 3.5m
c) 4.5m
d) 5m
Answer: b
Clarification: The eccentricity (e) = Z – b/2.
Z= distance between the centre of gravity and point where the resultant cuts the base is 5m.
= 5-3/2 = 1.5m.
2. Which of the following is not a failure of retaining wall?
a) Structural slide
b) Shear sliding
c) Crushing
d) Slope pitching
Answer: c
Clarification: Crushing Failure is related to dams. The retaining walls are the structures constructed to store earth on one side especially in case of hill or ghat roads.
3. ________ pressure which occurs commonly in dams.
a) Passive earth pressure
b) Active earth pressure
c) Soil moisture tension
d) Wind pressure
Answer: b
Clarification: Active earth pressure is exerted by backfill on retaining walls. It is also called as practical pressure. It occurs commonly in dams.
4. _________ failures contribute 40% to earthen dams.
a) Seepage
b) Structural
c) Hydraulic
d) Natural
Answer: c
Clarification: On the basis of various investigation reports and case studies, hydraulic failures contribute about 40% of failures to earthen dams. The rest of the failures is shared by seepage failures and structural failures.
5. Which of the following filters are also known as chimney drains?
a) Horizontal filter
b) Inclined filter
c) Rock toe
d) Toe drain
Answer: b
Clarification: The filters which are laid across the outer slope of the impervious core are called as inclined filters. They are also known as Chimney drains. They are provided mainly to collect the seepage emerging out of the core.
6. Zoned earthen dams are also known as ______
a) Heterogeneous dams
b) Core wall dams
c) Homogeneous dams
d) Hydraulic dam
Answer: a
Clarification: The dams are constructed on shallow pervious foundations in this dam section about outer zones are made fairly pervious material and the inner most zoning called “hearting” is done was fairly impervious material. It is also known as heterogeneous dam.
7. ___________ dams are built with key trenches.
a) Heterogeneous earth dam
b) Homogeneous earth dam
c) Earth Dam with Core wall
d) Rolled fill dam
Answer: c
Clarification: The outer zones of this dam are made of pervious material as in zoned dam. In this case, it is essentially build cut-off wall (cut-off trench) built quite deep preferably upto impervious rock layer in the foundation.
8. Line of seepage is also known as __________
a) Hydraulic gradient
b) Phreatic line
c) Seepage gradient
d) Hydraulic seepage line
Answer: b
Clarification: The line within the dam section below which there are positive hydrostatic pressures in a dam and above the line the hydrostatic pressures are negative. It gives a divide line between dry and saturated soils.
9. ____________ represents the top stream line.
a) Phreatic line
b) Hydraulic gradient line
c) Seepage gradient
d) Hydraulic seepage line