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288/33310–15FE Reference Handbook 10.4 · Civil · Geotechnical · Permeability
1. Effective Stress2. Rankine Active Earth Pressure3. Terzaghi Bearing Capacity (strip)4. Void Ratio5. Porosity and Degree of Saturation6. Moist Unit Weight7. Darcy’s Law (Seepage)8. Mohr–Coulomb Failure Criterion9. Primary Consolidation Settlement10. Atterberg Limits and Plasticity Index11. Relative Density of Sand12. Slope Factor of Safety13. Time Factor Tv and Drainage Path14. Pile Capacity: Tip and Skin15. Proctor Compaction16. Flow Net Discharge17. Rankine Passive Earth Pressure18. Retaining-Wall Sliding FS19. USCS Classification (Cu, Cc, PI)20. Coulomb Active Earth Pressure21. Immediate (Elastic) Settlement22. OCR and Preconsolidation Stress23. Infinite-Slope Factor of Safety24. Hazen Estimate of k25. Secondary Compression Cα

Handbook formula

Hazen Estimate of k

Order-of-magnitude only, for clean, loose, uniformly graded sand. Lab: constant-head (sand) k=QL/(A h t); falling-head (fines) k=(aL/At) ln(h1/h2).

(cm)
Effective grain size
Hazen coefficient ~100

Step-by-step solved example

Clean sand D10=0.2 mm=0.02 cm, C=100. k?

sandclayrockW.T.
k ≈ C D10² for clean sand; flow through the layer.

  1. 1. D10²

    0.0004.

  2. 2. k

    100×0.0004=0.04 cm/s = 4×10^{-4} m/s.

Answer: k ≈ 0.04 cm/s

10 practice questions

0/10 correct

1.Constant-head k=

2.Falling-head is preferred for

3.k of clay is nearest

4.D10=0.1 cm, C=100: k≈

5.Darcy q=k i with i=

6.Anisotropy k_h > k_v in

7.Pumping tests give a field k (or T) that

8.Void ratio up → k generally

9.C=100 is not for

10.1 cm/s =