The coefficient of consolidation is measured in:
Try it first: pick an option, then read the explanation.
Correct answer: B. cm²/sec
Asked in SSC JE 2012 / SSC JE 2004
Detailed Explanation
The coefficient of consolidation links the time factor, the drainage path and time:
\[ c_v = \frac{T_v\,d^2}{t} \]
Why “cm²/sec” Is Correct
Tv has no units, d² is an area and t is a time, so cv is an area per unit time: cm²/sec (or m²/year in field practice). The same result comes from cv = k/(mvγw): (cm/s) ÷ (cm²/g × g/cm³) = cm²/s.
Why the Other Options Are Wrong
- A. cm²/g: cm²/g has no time unit, so it cannot describe a rate of consolidation.
- C. g/cm²/sec: g/cm²/sec mixes mass and the inverse of area; it is not the dimension of cv.
- D. g-cm/sec: g-cm/sec is the unit of momentum.
Key Point
cv: length²/time (cm²/s, m²/yr). Same dimensions as a diffusion coefficient.
Key Concepts for Students
- Typical cv of clays: 10⁻⁴ to 10⁻² cm²/s.
- 1 cm²/s ≈ 315 m²/year.
- Tv is dimensionless; mv has units of m²/kN.
Practice more: this is question 25 in Soil Consolidation MCQs – Part 2. Try the whole set and check every answer instantly.