Direction: Water is following through the permeability apparatus as shown in the figure. The coefficient of permeability of the soil is k m/s and the porosity of the soil sample is 0.50.
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The total head, elevation head and pressure head in metres of water at the point R shown in the figure
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- 0.8, 0.4, 0.4
- 1.2, 0.4, 0.8
- 0.4, 0, 0.4
- 1.6, 0.4, 1.2
Correct Option: C
Here overflow level of water is taken as datum
Total head loss, ∆h = 0.4 + 0.8 = 1.2 m
Depth of sample, l = 1.2 m.
hydraulic gradient,
| i = | l |
| = | = 1 | 1.2 |
Total head at R = 1.2 – 0.8 × 1 = 0.4 m
Here datum head = 0 (datum is at R) (elevation head)
Total head = pressure head + datum head
0.4 = pressure head + 0
∴ pressure head = 0.4 m
