Font size
WorksheetsQuiz on Unit 3
Total questions: 85
Worksheet time: 1hrs 25mins
1. Which of the following earth dam is suitable only on impervious foundation?
Zoned embankment type
Homogenous embankment type
Non-homogenous type
Diaphragm type
2. Which of the following zone in Zoned type embankment prevents piping through cracks?
Central core
Transition zone
Outer zone
Core wall
3. Which embankment has the thickness of the diaphragm at an elevation less than 10 meters or the height of the embankment above the corresponding elevation?
Diaphragm type dam
Zoned type dam
Non-homogenous earth dam
Homogenous earth dam
4. The blanket in earth dam is provided ___________________
at the ground level on u/s side
at the ground level on the d/s side
at the ground level of the D/s side of the dam
on the D/s slope
5. Which of the following statement is correct with reference to earthen dams?
These dams are very costly as compared to other types
Gravity dams are less susceptible to failure as compared to rigid dams
These dams are suitable for construction on almost every type of foundation
Highly skilled labor is generally not required
6. During the construction of an earthen dam by hydraulic fill method, development of pore pressure becomes important in the ________
central impervious core
pervious outer shell
transition zone
both central core and outer shell
7. The process of laying and compacting earth in layers by power rollers under OMC for construction of earthen dams is known as ______________________
Rolled fill method
Hydraulic fill method
OMC method
Compaction
8. The central core of the zoned embankment type earth dam ___________
checks the seepage
prevents piping
gives stability to the central impervious fill
distribute the load over a large area
9. Which type of dam is suitable on shallow pervious foundations?
Zoned embankment type
Homogenous embankment type
Both Non-homogenous type and homogenous type
Diaphragm type
10. What is the U.S.B.R recommended value for freeboard when the height of the dam is more than 60 m?
2 m to 3 m
2.5 m above the top of gates
3 m above the top of gates
More than 3 m
11. What is the recommended formula for top width of a very low dam?
H + 3
0.2H + 3
0.2 H
H + 5
12. Calculate the top width (a) of the earth dam of height 50 m
5.0 m
4.75 m
6.10 m
3 m
13. A phreatic line in seepage analysis is defined as the line on which pressure is ________
equal to the atmosphere
greater than atmosphere
lower than atmosphere
varying
14. Provision of horizontal berms at suitable vertical intervals may be provided in the downstream face of an earthen dam in order to _________
allow the movement of cattle
allow the inspection of vehicles to move
reduce the erosion caused by the flowing rainwater
increase the erosion
15. During seepage through an earthen mass, the direction of seepage is ________________ to the equipotential lines.
perpendicular
parallel
not defined
diagonal
16. The upstream face of the earth dam is considered as __________
equipotential line
streamline
streak line
path line
17. Which of the following line acts as a dividing line between dry (or moist) and submerged line?
a) Equipotential line
Equipotential line
Path line
Seepage line
Streak line
18. Stone pitching or riprap is generally provided to avoid __________
over-topping
erosion of U/s and d/s face
cracking due to frost action
gully formation
19. Provision of sufficient freeboard eliminates _______________
i. Over-topping failure
ii. Erosion of U/s face
iii. Erosion of D/s face
iv. Cracking due to frost action
v. Gully formation
Which of the following is/are correct?
i and v
ii and iii
iv and v
i and iv
20. The collection and removal of water before it acquires high downward velocities is ensured by provision of ___________
berms
freeboard
burrow pits
spoil banks
21. Sloughing is the process of _________
progressive erosion
subsequent removal of soil grains from within the dam
uncontrolled seepage through the dam body
progressive removal of soil from the D/s face
22. In foundation slide failure___________
top of embankment gets cracked and lower slope moves outward forming large mud waves near the heel
top of embankment gets cracked and lower slope moves inward forming large mud waves near the heel
bottom of embankment gets cracked and lower slope moves outward forming large mud waves near the heel
bottom of embankment gets cracked and lower slope moves inward forming large mud waves near the heel
23. What is the most critical condition of slide of the U/s slope?
The sudden drawdown of the reservoir
Reservoir full condition
Steady seepage condition
Sudden drawdown and reservoir full condition
24. In order to keep the saturation line in a canal embankment well within the toe, it is necessary to provide ___________
spoil bank
counter berm
freeboard
berm
25. The safety valve of a dam is its _________
drainage gallery
inspection gallery
spillway
outlet sluices
26. Which of the following is the simplest type of spillway and may be constructed on small bunds or thin arch dams?
Straight drop spillway
Ogee spillway
Shaft spillway
Siphon spillway
27. The spillway can be best built independently of the dam when there is __________
deep narrow gorge with steep slopes
deep narrow gorge with gradual slopes
wide gorge with a gradual slope
wide valley with moderate slopes
28. Which of the following is a secondary safety arrangement?
Safety valves
Spillway gates
Subsidiary spillway
Energy dissipaters
29. Which of the following spillway is least suitable to earthen dams?
Ogee spillway
Chute spillway
Side-channel spillways
Shaft spillway
30. If the operating head on an ogee spillway is more than the design head then __________
the pressure on the crest will be zero
the pressure on the crest will be negative causing cavitation
the pressure on the crest will be positive
the discharge coefficient of the spillway will be reduced
31. In the functioning of an ogee spillway, the operating head _________
frequently exceeds the design head
rarely exceeds the design head
never exceeds the design head
has no connection with the design head
32. If the head of the water over the spillway is less than the design head, then ____
the pressure on the crest will be zero
the pressure on the crest will be negative causing cavitation
the discharge coefficient of the spillway is increased
the discharge coefficient of the spillway will be reduced
33. The spillway which can be called as an overflow spillway is essentially ___________
an ogee spillway
a shaft spillway
a chute spillway
a syphon spillway
34. The W.E.S downstream profile of an ogee spillway can be represented by an equation:
Where x and y are the coordinates of the points on the crest profile and K and n for a vertical upstream spillway would respectively be___________________
2.0 and 1.85
0.5 and 1.85
2.0 and 0.85
0.5 and 0.85
35. According to US Army Corps, the u/s profile of ogee spillway extends up to ________
x = 1.27 Hd
x = -1.27 Hd
x = 0.431 Hd
x = -0.431 Hd
36. If the upstream face of the spillway is kept vertical, the crest shape should also confirm to the lower nappe of an inclined sharp-crested weir
H
H2
H1/2
H3/2
37. When the crest of an ogee spillway is designed to be in accordance with the lower nappe of a free-falling water jet over a duly ventilated sharp-crested weir then theoretically
The pressure on the spillway crest will be zero at design head only
The pressure on the spillway crest will always be zero
The pressure on the spillway crest will always be negative
The pressure on the spillway crest will be always positive
38. The velocity of approach has found to be negligible effect upon discharge if ____________
the ratio H/Hd is more than 1.33
the ratio H/Hd is less than 1.33
the ratio H/Hd is equal to zero
the ratio H/Hd is more than 1
39. If a flood enters a dam reservoir at F.R.L, the efficiency of its ogee spillway will ______________
increase with the increasing head
reduce with the increasing head
remain constant with the increasing head
vary with the increasing head
40. The downstream apron of the ogee spillway is found to have a negligible effect on the coefficient of discharge when the value of ________________
(Hd + d) / He is less than 1.7
(Hd + d) / He exceeds 1.7
(Hd + d) / He is equal to 1
(Hd + d) / He is less than 1.33
41. What is the value of the pier abutment coefficient for pointed nose piers?
0.1
0.02
0.01
0.0
42. What is the value of abutment contraction coefficient for square abutment with headwall perpendicular to the direction of flow?
0.2
0.1
0.02
0.01
43. What is the assumption that is taken during the entire design of an overflow spillway?
The upper and lower nappe is subjected to negative pressures
The upper and lower nappe is subjected to full atmospheric pressure
The upper and lower nappe is subjected to zero atmospheric pressure
The upper and lower nappe is subjected to both positive and negative pressure
44. Calculate the effective length of the spillway which consists of 6 spans having a clear width of 10 m each. The thickness of each pier may be taken as 2.5 m and the total design head on the crest including velocity head is 16.3 m. Assuming 90° cut water nose piers and rounded abutments.
55 m
60 m
65 m
75 m
45. Which of the following is the simplest type of spillway which can be provided independently and at low costs?
Ogee spillway
Trough spillway
Siphon spillway
Saddle spillway
46. The spillway which can be adopted with ease on gravity as well as earthen dams is ____
ogee spillway
chute spillway
both ogee and chute spillway
straight drop spillway
47. The surplus reservoir water after spilling over the crest of the spillway flows on the chute is _________
parallel to the crest in a trough spillway
parallel to the crest in a side-channel spillway
perpendicular to the crest in a side-channel spillway
obliquely to the crest in a chute spillway
48. The portion of a chute spillway which is known as its control structure is ________________
low ogee weir
chute channel
approach channel leading the water from the reservoir to the ogee weir
silting basin at its bottom
49. The type of spillway which is provided on narrow valleys where no side flanks are available is _________________
ogee spillway
chute spillway
side-channel spillway
straight drop spillway
50. Calculate the freeboard for the top levels of the side walls if the mean velocity of water in the chute reach is 3.5 m/s and the mean depth of water in the chute reach under consideration is 4.7 m
0.60 m
1 m
0.85 m
0.55 m
51. The minimum slope of the chute is governed by the condition that _____________
the subcritical flow must be maintained
the supercritical flow must be maintained
a critical flow must be maintained
maybe supercritical or subcritical flow is possible
52. A shaft spillway is located _______________________
inside the body of a gravity dam
inside the upstream reservoir
inside the downstream reservoir
on the side flanks of the main dam
53. The siphons installed over overflow dams constitute what are known as __________________
hooded type siphon spillway
tilted outlet type siphon spillway
discharge carriers
baby siphons
54. The only spillway among the following through which the discharge does not increase as fast as it increases in all others is _________________
chute spillway
side-channel spillway
ogee spillway
shaft spillway
55. The only spillway among the following through which the discharge is almost at its capacity rate even from the start of its functioning is ________________
chute spillway
side-channel spillway
ogee spillway
siphon spillway
56. An air vent is provided at FRL to break the siphoning action at that level in a ________
hooded type of siphon spillway
tilted outlet type of siphon spillway
saddle siphon spillway
volute siphon spillway
57. The crest of a siphon spillway is fixed at ________________
full reservoir level
dead storage level
maximum water level
top of the dam
58. A siphon spillway is sufficiently independent of the water surface elevation of the reservoir
True
False
59. The allowable maximum negative head on an average is equal to __________
2.5 m or so
5 m or so
7.5 m or so
10 m or so
60. The structure which is not used in a shaft spillway is ________________
tunnel
bridge
radial gates
radial piers
61. Morning glory is the _________
special flared inlet of the shaft spillway of a dam of very small height
special flared inlet of the shaft spillway of a large dam project
a horizontal tunnel constructed in a shaft spillway across the body of a gravity dam to carry surplus reservoir water to the d/s river
a horizontal tunnel constructed in a shaft spillway of an earthen dam through its foundation to carry surplus reservoir water to the d/s river
62. A siphon spillway in a concrete gravity dam is in the shape of ________________
U-shape
Inverted U-shape
Horizontal bend through the abutment
Any straight line
63. The energy dissipation at the toe of the spillway is affected basically by the use of hydraulic jump in ____________
roller bucket
a ski-jump bucket
a sloping apron below the downstream river bed
both roller and ski-jump bucket
64. The most ideal condition for energy dissipation in the design of spillways is the one when the tail-water rating curve coincides with the jump rating curve at all discharge
True
False
65. When the tail-water depths in the river downstream of a spillway are quite low such that the tail-water curve at all discharges lies below the post jump depth curve, then the energy dissipation can be affected best by ________
a roller bucket
a ski-jump bucket
either roller or ski-jump bucket
a sloping apron
66. The formation of hydraulic jump at the foot of a spillway is one of the common methods of energy dissipation because ____________
it destroys more than 90% of total energy by the turbulence produced in the jump
it reduces the kinetic energy by increasing the depth of flow
its action is not understood
it reduces the kinetic energy by decreasing the depth of flow
67. The percentage of energy dissipation in a hydraulic jump increases with the increase in the Froude number
True
False
68. Which of the following stilling basin help in stabilizing the flow and improve the jump performance?
dentated sills
chute blocks
baffle piers
friction blocks
69. What is the expected solution for the case when the T.W.C is lying above the J.H.C curve at all discharges?
By providing a simple concrete apron of length 5(Y1 – Y2)
By providing a sloping apron above the river bed
By providing a sloping apron below the river bed
Provision of a ski-jump bucket
70. A sloping apron is provided partly above the river bed and partly below the river bed in case ____________
when TWC coincides with the JHC at all discharges
when TWC lies above the JHC at all discharges
when TWC lies below the JHC at all discharges
when TWC lies above the JHC at low discharges and below the JHC at high discharges
71. When the TWC lies below the JHC at all discharges, the problem can be solved by which of the following provisions?
i. Constructing a sloping apron above the river bed
ii. Provision of roller bucket type of energy dissipator
iii. Provision of a ski-jump bucket
iv. A sloping apron below the river bed
v. Construction of a subsidiary dam
vi. A sloping apron partly above and partly below the river bed
i, iii and v
i, ii and vi
iii, iv and v
i, iii, iv and v
72. An oscillating hydraulic jump is normally met in cases of _____________
weirs and barrages
overflow spillways of dams
weirs
large spillways
73. A very steady and stable hydraulic jump is usually formed in the flows involving the approaching Froude number in the range of _________
less than 2.5
2.5 to 4.5
4.5 to 9.0
more than 9.0
74. Standard USBR stilling basin-II is useful for energy dissipation at the bottom of the overflow structure, if the approaching Froude number is ______
less than 4.5
less than 4.5
less than 2.5
more than 2.5
75. When the Froude number is in the range of 2.5 to 4.5, the jump is _________
weak and energy loss is low
oscillating jump
steady jump
strong jump
76. Which of the following stilling basin is applicable to only rectangular cross-sections?
U.S.B.R stilling basin-II
U.S.B.R stilling basin-IV
U.S.B.R stilling basin-I
U.S.B.R stilling basin-III
77. The Froude number of a hydraulic jump is 5.5. The jump can be classified as ____________
a weak jump
an oscillating jump
rough and choppy jump
steady jump
78. Standard stilling basin is provided at the toe of a dam spillway for energy dissipation is usually provided with auxiliary devices like chute blocks and dentated sills for the basic purpose of reducing the length of the stilling basin from about ______
6 y2 to 4 y2
4 y2 to 2 y2
6 y2 to 2 y2
3 y2 to y2
79. In the case of dam spillways, the approaching Froude number usually lies in the range of __________
less than 2.5 m
2.5 – 4.5
4.5 – 9.0
more than 9.0
_____________________ are suitable only for low spillways or weirs
Chute blocks
Sloping aprons
Baffle wall or friction blocks
Roller buckets
81. An ogee spillway of a concrete gravity dam having FRL of 328 m and MWL of 340 m is provided with vertical gates between piers erected on the spillway. The effective length of the spillway is 60 m. The discharge through the spillway when gates are opened up to the actual reservoir level of 331.0 m will be_____________
850 cumecs
1700 cumecs
2800 cumecs
1000 cumecs
82. Which of the following gate works on the principle of counterweights against the water pressure?
Dropping shutters
Stop logs and needles
Stoney roller gate
Drum gates
83. ____________ are used only for very minor works
Dropping gates
Stop logs and needles
Rectangular gates
Drum gates
84. Which of the following gate is not suitable for smaller spillways?
Drum gates
Radial gates
Needles and stop logs
Fixed roller gates
85. The discharge passing over an ogee spillway per unit length of its apex line is proportional _____
H
H2
H1/2
H3/2
