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In a falling head permeability test the initial head of 1.0 m dropped to 0.35 m in 3 hours, the diameter of the stand pipe being 5 mm. The soil specimen was 200 mm long and of 100 mm diameter. The coefficient of permeability of the soil is:
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- 4.86 × 10–5 cm/s
- 4.86 × 10–6 cm/s
- 4.86 × 10–7 cm/s
- 4.86 × 10–8 cm/s
Correct Option: B
| a = | × (0.5)2 | 4 |
= 0.196 cm2
| Ax = | × (10)2 | 4 |
= 78.5 cm2
L = 20 cm
h1 = 100 cm, h2 = 35 cm
t = 3 hours
| k = | . log | |||
| At | h2 |
| = | In |  |  | ||
| 78.5 × 3 | 35 |
= 0.0175 cm/hr
= 4.86 × 10–6 cm/s
