# Geotechnical Engineering Questions and Answers – Seepage Analysis – Phreatic Line of an Earth Dam

This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Seepage Analysis – Phreatic Line of an Earth Dam”.

1. What are the essentials, required to draw a flow net?
a) Top Flow and Phreatic line
b) Stream line
c) None of the mentioned
d) All of the mentioned

Explanation: In order to draw the flow net, it is first essential to find out the location and shape of the phreatic line and top flow line separating the saturated and unsaturated zones.

2. The phreatic line can be located by which of the following method?
a) Graphical method
b) Experimental method
c) Analytical method
d) All of the mentioned

Explanation: As suggested by casagrande, the phreatic line can be located by graphical, experimental and analytical methods.

3. Kozney’s top flow lines is called as ____________
a) Basic and Base parabola
b) Simple parabola
c) None of the mentioned
d) All of the mentioned

Explanation: Kozney’s solution for flow of water consists of a family of confocal parabola s representing the flow lines. Hence kozney’s top flow line is called the basic or base parabola.

4. For the water flowing above an impervious, infinite, horizontal plane. The net flow is given by ___________
a) Casagrande
b) Kozney
c) Forchheimer
d) Darcy

Explanation: In 1938, kozney analytically derived a flow net for the case of water flowing above an impervious, infinite, horizontal plane which at a certain place becomes permeable.

5. What is the line within a dam section, below which there are positive hydrostatic pressures?
a) Phreatic and Seepage line
b) Equipotential line
c) None of the mentioned
d) All of the mentioned

Explanation: The phreatic line or seepage line is the line within a dam section below which there are hydrostatic pressures in the dam. The hydrostatic pressure below on the phreatic line itself is atmospheric.
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6. The flow lines and equipotential proposed by Kozney is in the shape of ____________
a) Hyperbola
b) Ellipse
c) Parabola
d) Circle

Explanation: According to flow net derived by Kozney, the flow lines and equipotential consist of the shape of parabola.

7. The analytical solution of schaffernak and Van Iterson gave result only for slopes, having __________
a) α>30°
b) α<30°
c) α>60°
d) α<60°

Explanation: The analytical solution of schaffernak and van iterson provided result, as long as slope is gentle i.e., α<30°. For steeper slopes, the deviation form correct values increases rapidly beyond tolerable limits.

8. What kind of method was suggested by Casagrande, for determining the phreatic line?
a) Experimental method
b) Analytical method
c) Graphical method
d) All of the mentioned

Explanation: Graphical method was used by Casagrande for the determination of the phreatic line using flow net.

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