Test: Phreatic Line Of An Earth Dam

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

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

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.

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.

 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.