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GATE 2016 CE (CE2) – Question 50

Geotechnical Engineering · Permeability and seepage: flow nets, uplift pressure, piping, capillarity · 2 marks · Numerical answer

The seepage occurring through an earthen dam is represented by a flownet comprising of 10 equipotential drops and 20 flow channels. The coefficient of permeability of the soil is 3 mm/min and the head loss is 5 m. The rate of seepage (expressed in cm3/s per m length of the dam) through the earthen dam is _________.

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Correct answer: 495 to 505

Explanation

Seepage per unit dam length is q=kH(Nf/Nd). Convert permeability3mm/min to0.003/60=0.00005m/s. With H5m and channel-to-drop ratio20/10=2, q=0.0005m³/s per metre. Since1m³=10⁶cm³, this is **500cm³/s per metre**.