Question Five:

For the concrete gravity retaining wall below,

$($a$)$ Draw an appropriate flow net on the diagram provided for constant water flow from water level A to B$.$ In your diagram, label a typical flow line, flow tube, equipotential line and equipotential drop to show your understanding.

$($b$)$ Using your flow net, calculate the discharge beneath the retaining wall $($in litres per minute per meter length of wall$)$ based on the permeability of the soil being $\backslash (0\mathrm{.}4\backslash$mathrm$\{$~cm$\}/\backslash$mathrm$\{$sec$\}\backslash )$ and the head loss between level A and B to be $12$ m $.$

Use Nf$=3$ & Nd$=10.$ Answer should be $916-928$ litres$/$min per m length of wall