250+ TOP MCQs on Forces and Loads on Sewer and Answers

Environmental Engineering Multiple Choice Questions on “Forces and Loads on Sewer”.

1. The magnitude of hoop stress on sewer is given __________
a) PD/2t
b) PD/t
c) 2PD/t
d) PD/2
Answer: a
Clarification: The magnitude of hoop stress on sewer is given by PD/2t where, P is the internal pressure, D is the diameter of sewer and t is the thickness of the shell.

2. In order to reduce temperature stress ______________ joints are provided.
a) Contraction
b) Expansion
c) Bell and spigot
d) Collar
Answer: b
Clarification: In order to reduce temperature stress, expansion joints are provided at intervals of 20m to 30m.

3. The expression for the temperature stress is given by __________
a) EPαt
b) EPαt/2
c) 2EPαt
d) EP/αt
Answer: a
Clarification: The expression for the temperature stress is given by EPαt where, EP is the modulus of elasticity of pipe, α is the coefficient of thermal expansion and ‘t’ is the change in temperature.

4. The type of backfill is saturated clay. What is its unit weight?
a) 1040kg/m3
b) 2080kg/m3
c) 2000kg/m3
d) 1500kg/m3
Answer: b
Clarification: When the type of backfill is saturated clay, then its unit weight is 2080kg/m3.

5. Which of the following has the minimum unit weight?
a) Dry sand
b) Wet sand
c) Damp clay
d) Ordinary sand
Answer: a
Clarification: The unit weight of wet sand, damp clay, ordinary sand and dry sand are 1920kg/m3, 1920kg/m3, 1840kg/m3 and 1600kg/m3 respectively.

6. The type of soil is loose dry sand. What is the coefficient of cohesion of the soil?
a) 100
b) 200
c) 500
d) 0
Answer: d
Clarification: Loose dry sand is a cohesionless soil. So, the value of the coefficient of cohesion is 0.

7. Which of the following order is correct regarding coefficient of cohesion?
a) Hard clay < Dense sand > Medium clay > Soft clay
b) Hard clay > Dense sand > Medium clay > Soft clay
c) Medium clay > Dense sand > Hard clay > Soft clay
d) Dense sand > Medium clay > Hard clay > Soft clay
Answer: b
Clarification: The coefficient of cohesion of Hard clay, Dense sand, Medium clay and Soft clay are 4700kg/m2, 1400kg/m2, 1200kg/m2 and 200kg/m2 respectively.

8. How many types of underground sewer are there on the basis of construction conditions?
a) 2
b) 3
c) 4
d) 5
Answer: b
Clarification: Depending upon the type of the construction conditions, underground sewers are of 3 types, namely Trench ditch condition, Embankment condition and Tunnel condition.

9. _______ condition exists when the sewer is laid at a depth between 9m to 12m.
a) Trench ditch
b) Trench
c) Tunnel
d) Embankment
Answer: c
Clarification: Tunnel condition exists when the sewer is laid at a depth between 9m to 12m. This process is done by jacking or by tunneling.

10. Negative projecting condition is a type of ______ condition.
a) Trench ditch
b) Trench
c) Tunnel
d) Embankment
Answer: d
Clarification: Negative projecting condition exists when the trench is narrower with respect to the size of the pipe and shallow with respect to the depth of cover.