# Geotechnical Engineering Questions and Answers – Seepage Analysis – Phreatic Line of an Earth Dam with No Filter

This set of Soil Mechanics Quiz focuses on “Seepage Analysis – Phreatic Line of an Earth Dam with No Filter”.

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

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

2. 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

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

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

4. 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

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. 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

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

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

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

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. In the figure the face KF is _________

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

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

Explanation: The slope α of discharge face can even exceed 90°. This can be the case of rock -fill toe. The correction $$\frac{\Delta a}{1+\Delta a}$$ for 90° is given by Casagrande as 0.26.

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