Engineering Questions with Answers - Multiple Choice Questions

Seepage Analysis – Phreatic Line of an Earth Dam with No Filter

1 - Question

The phreatic line can be located by Casagrande method.
a) True
b) False

View Answer

Answer: a
Explanation: The phreatic line can be located by analytical method, graphical method-Casagrande method and experimental method.




2 - Question

The phreatic line is the ________
a) top flow line separating saturated and unsaturated zones
b) middle flow line separating saturated and unsaturated zones
c) bottom flow line separating saturated and unsaturated zones
d) bottom flow line separating saturated and partially saturated zones

View Answer

Answer: a
Explanation: The location and shape of phreatic line or the top flow line separating saturated and unsaturated zones is the first essential step to draw flow net.




3 - Question

 The phreatic line is also known as the ________
a) seepage line
b) discharge line
c) velocity line
d) pressure line

View Answer

Answer: a
Explanation: The phreatic line or seepage line is the line within a dam section below which there are positive hydrostatic pressures in dam.




4 - Question

The phreatic line is defined as the line within a dam section below which there are ________ in dam.
a) positive hydrostatic pressures
b) negative hydrostatic pressures
c) neutral hydrostatic pressures
d) no hydrostatic pressure

View Answer

Answer: a
Explanation: The phreatic line or seepage line is defined as the line within a dam section below which there are positive hydrostatic pressures in dam.




5 - Question

 The focus in an earth dam with no filter is ________
a) lowest point of d/s slope
b) highest point of d/s slope
c) high flood level
d) medium flood level

View Answer

Answer: a
Explanation: The focus in an earth dam with no filter is lowest point F of d/s slope.




6 - Question

The base parabola is the ________
a) top flow line
b) middle flow line
c) bottom flow line
d) ¼ of top flow line

View Answer

Answer: a
Explanation: The Konzeny’s top flow line is called as the basic parabola or the base parabola. The focus in an earth dam with no filter is the lowest point of d/s slope.




7 - Question

In the earth dam with no filter, the base parabola does not cut the d/s slope.
a) True
b) False

View Answer

Answer: b
Explanation: In the earth dam with filter, the base parabola does not cut the d/s slope. But in the earth dam with no filter, the base parabola will evidently cut the d/s slope




8 - Question

In the figure the face KF is _________

a) seepage face
b) velocity face
c) discharge face
d) pressure face

View Answer

Answer: c
Explanation: The phreatic line emerges out at point K meeting d/s face tangentially. Point F is the focus of the base parabola. The face KF is the discharge face and it always remains wet.




9 - Question

 The slope of discharge face can exceed _______
a) 30°
b) 45°
c) 60°
d) 90°

View Answer

Answer: d
Explanation: The slope α of discharge face can even exceed 90°. This can be the case of rock -fill toe. The correction Δa1+Δa for 90° is given by Casagrande as 0.26.

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