This set of Tricky Strength of Materials Questions and Answers on “Trapezoidal Dam as Vertical Side Phase”.
1. Calculate the horizontal water pressure acting on a dam. The total depth of water be 13m. Take specific weight of water be 10kN/m3.
a) 765 kN
b) 845 kN
c) 965 kN
d) 1175 kN
Answer: b
Clarification: Horizontal water pressure(P) = w×h2/ 2.
Where w = 10 kN/m3. h= 13m.
P = 10×132/ 2 = 845kN.
2. Calculate the self-weight of a rectangular dam of 22m high and 8m wide. It contains water upto a height of 20m. Consider the specific weight of masonry be 25 kN/m3.
a) 3560 kN
b) 5432 kN
c) 4400 kN
d) 5680 kN
Answer: c
Clarification: Consider 1m length of the dam. The total depth of dam is 22 metres.
Self weight of masonry (W)= (22×8)×1×25
= 4400kN.
3. The pressure intensity of water at free surface is ________
a) Zero
b) Maximum
c) Minimum
d) Uniform
Answer: a
Clarification: The pressure intensity of water at a free surface is always zero and increase linearly to a maximum at the base and is equal to “ wh”.
4. Self weight of dam acts in ___________ direction.
a) Vertical
b) Horizontal
c) Inclined
d) Parallel
Answer: a
Clarification: Self weight of the Dam at vertically downwards passing through centre of gravity of the damn section and Total horizontal water pressure acts horizontally at heel of the dam.
5. The maximum compressive stresses developed at the base of the dam should not exceed permissible ___________ stresses for masonry.
a) Tensile
b) Crippling
c) Compressive
d) Shear
Answer: c
Clarification: To avoid the failure of crushing, the maximum compressive stress developed at the base of the dam should not exceed the permissible compressive stress for masonry with which the dam is constructed.
6. For no _______ to develop in the dam section the resultant should always lie within the middle third.
a) Compression
b) Tension
c) Shear
d) Buckling
Answer: b
Clarification: For no tension to develop in the dam section at any condition, the eccentricity developed with the resultant should be always less than b/6. The resultant must always lie within the middle third.
7. Calculate the self weight of trapezoidal dam with top width 5m and bottom width 8m. The height of dam is 15 m. Consider specific weight of masonry be 25kN/m3.
a) 3456.5 kN
b) 2768.5 kN
c) 2437.5 kN
d) 3450 kN
Answer: c
Clarification: Consider 1m of length, area of trapezoidal dam be (a+b)/2 ×H
The self weight of trapezoidal dam (W) = (a+b)/2 × H × 1 × 25
W = 2437.5 kN.
8. The material(earth) retained by the retaining wall is called as __________
a) Surcharge
b) Turf
c) Foliate
d) Back fill
Answer: d
Clarification: The material retained by the retaining wall is called back fill. The top surface of the back fills maybe him the horizontal or inclined.
9. The inclination of surcharge to the horizontal is called ____________
a) Surcharge elevation
b) Surcharge angle
c) Surcharge factor
d) Surcharge depression
Answer: b
Clarification: The back fill lying above a horizontal plane at an elevation of the top of wall is known as a surcharge and its inclination to the horizontal is called surcharge angle.
10. Which of the following is practical pressure?
a) Active earth pressure
b) Passive earth pressure
c) Soil moisture tension
d) Horizontal water pressure
Answer: a
Clarification: The pressure exerted by back fill on retaining wall is called an active earth pressure. This is the minimum earth pressure exerted by the soil. This is also known as practical pressure.
11. The angle of internal friction for water is __________
a) 180°
b) 100°
c) 0°
d) 270°
Answer: c
Clarification: Angle of internal friction is defined as the maximum slope at which the particles of soil will come in rest due to their internal friction. It is also called an angle of repose for water it is 0°.
12. Which of the following is theoretical pressure?
a) Active earth pressure
b) Passive earth pressure
c) Soil Tension
d) Horizontal water pressure
Answer: b
Clarification: The pressure exerted by the retaining wall on the retained earth is called passive earth pressure. This is a maximum earth pressure due to maximum shear stress on the retaining wall. This is also known as theoretical pressure.
13. Which of the following is an example for plasticizer?
a) Ca
b) Mg
c) Zn
d) Hg
Answer: a
Clarification: The combination of both inorganic and organic materials which will help to reduce the water content for getting higher workability are known as plasticizers. Examples are calcium, sodium, salts of hydrocarbons etc.
14. _______ curing is adopted for columns and walls.
a) Moist curing
b) Membrane curing
c) Ponding
d) Descending stage
Answer: a
Clarification: In this curing, the exposed surface of the concrete is kept in a damp and moist condition for a long time, the vertical members like columns and walls can be adopted for this type of curing.
15. Prestressed concrete is an example of _____________
a) Malleability
b) Ductility
c) Fatigue
d) Plasticity
Answer: c
Clarification: Fatigue is the property of a material by which the material with stands to repeating, reversing or varying upcoming loads. The best example of fatigue is concrete and prestressed concrete.
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