Engineering Questions with Answers - Multiple Choice Questions

# Seepage Pressure and Upward Flow – 1

1 - Question

Seepage force is the energy transfer between __________
a) air and water
b) water and soil
c) air and soil
d) earth and air
Explanation: The energy transfer is affected between water and soil by virtue of viscous friction exerted on water flowing through the soil pores. The force corresponding to this energy transfer is called seepage force.

2 - Question

Seepage pressure is responsible for quick sand condition.
a) True
b) False
Explanation: When the water flows or percolates through the soil mass, then it produces stresses in the soil particles by virtue of seepage pressure. When this pressure is equal to submerged unit weight γ’ of soil, quick sand condition is obtained.

3 - Question

The first rational approach to the problem of seepage through soils was ________
a) Archimedes
b) Poiseuille
c) Darcy
d) Terzaghi
Explanation: The first rational approach to the problem was presented by Terzaghi in 1922 and it forms the basis of subsequent studies.

4 - Question

The seepage pressure ps is given by _________
a) hγw
b) h/γw
c) h+γw
d) h-γw
Explanation: The seepage pressure ps is given by, ps= hγw, where, h=hydraulic head or head lost due to frictional drag of water flowing through soil mass γw=uniy weight of water.

5 - Question

The seepage pressure ps with respect to hydraulic gradient i is given by ________
a) ihγwz
b) iγwz/h
c) iγwz
d) ih/zγw
Explanation: The seepage pressure ps is given by, ps=hγw, if z=length over which head is lost, ∴ ps=(h/z)zγw=iγwz.

6 - Question

The relationship between seepage force J and seepage pressure ps is given by _______
a) J=ps /A
b) J=ps +A
c) J=ps –A
d) J=ps A
Explanation: Since the pressure is equal to force by area, ps =J/A ∴ J=ps A.

7 - Question

The seepage force J with respect to hydraulic gradient i is given by ________
a) ihγwzA
b) iγwz/hA
c) iγwzA
d) ih/zAγw
Explanation: The seepage force J is given by, J=ps A Since ps =iγwz ∴ J= iγwzA.

8 - Question

The seepage force per unit volume j is given by _______
a) j=iγwzA
b) j=izA
c) j=iγw
d) j=zA
Explanation: The seepage force per unit volume j is given by, J=J/V Where, J= iγwzA V=zA ∴ j= iγwzA/zA ∴ j=iγw.

9 - Question

The seepage pressure always acts _______
a) in the direction of flow
b) opposite to direction of flow
c) perpendicular to direction of flow
d) tangential to direction of flow
Explanation: When the water flows through a soil mass, due to its viscous friction, an energy transfer is effected between water and soil. This energy transfer is seepage pressure.

10 - Question

The effective pressure subjected to seepage pressure is given by _______
a) σ’=zγsat*izγw
b) σ’=zγ’*izγw
c) σ’=zγ’±izγw
d) σ’=zγ’/izγw
Explanation: Depending on the direction of flow, the vertical effective pressure is increased or desreased. The effective pressure subjected to seepage pressure is given by, σ’=zγ’± ps = zγ’±izγw.

11 - Question

In ______ direction of flow, the effective pressure is increased.
a) perpendicular
b) tangential
c) upward
d) downward
Explanation: The effective pressure subjected to seepage pressure is given by, σ’=zγ’± ps = zγ’±izγw. If the flow occurs in downward direction, + sign is used. If the flow occurs in upward direction – sign is used.

12 - Question

The quick condition takes place when effective pressure is _______
a) σ’=0
b) σ’=1
c) σ’= zγ’+ ps
d) σ’= zγ’
Explanation: When seepage pressure equals the pressure due to submerged unit weight γ’, quick condition takes place. ∴ σ’= zγ’- ps ∴ σ’=0.

13 - Question

The critical hydraulic gradient is given by _______
a) ic = γ’/ γw
b) ic = γ’+ γw
c) ic = γ’-γw
d) ic = γ’