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GATE 2016 CE (CE1) – Question 56

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

Seepage is occurring through a porous media shown in the figure. The hydraulic conductivity values (k1, k2, k3) are in m/day. The seepage discharge (m3/day per m) through the porous media at section PQ is

Diagram for GATE 2016 CE (CE1) question 56
  1. 7/12
  2. 1/2
  3. 9/16
  4. 3/4

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Correct answer: (B) 1/2

Explanation

For series flow, discharge is common and individual head losses add. Per metre width the cross-sectional area is3m², and resistance sum L/k is20/2+30/3+10/1=30days. With total head difference5m, Q=AΔh/sum(L/k)=3·5/30=0.5m³/day per metre. Thus **B**; average conductivity must be weighted harmonically.