Test: Application Of Flow Net - Civil Engineering (CE) MCQ

A flow net can be utilized for determination of seepage, seepage pressure .hydrostatic pressure, and exit gradient.

The portion between any two successive flow lines is called as flow channel and the portion enclosed between two successive equipotential lines and successive flow lines is known as field.

The graphical method of flow net construction first given by Forchheimer in 1930, based on trial sketching.

The electric models suggested by ohm, have the same geometric shape as the soil through which the water flows. And both Darcy and ohm’s law have corresponding analogous quantities.

The flow lines and equipotential lines always meet at right angles to one another.

The equation hW=h – Z ,can be used to plot pressure net representing lines of equal water pressure without the saturated soil mass since all the three quantities in the equation can be expressed a the percentage of total hydraulic head H.

 The seepage medium is replaced by an electric conductor consisting of water with some salt or dilute hydrochloric acid.

Using the formula, hW= h -Z
30 = h -10
h=30+10 =40
Hydrostatic pressure, h=40 %.

According to practical suggestion given by A.Casagrande, every transition in the shape of curve is smooth, being either elliptical or parabolic in shape.

ie =Δh/i, represent gradient formula where Δ h=potential drop and l is the average of last field in the flow net at exit end.