The uniformity coefficient of soil is
- AD₆₀/D₁₀Correct
- BD₃₀/D₁₀
- CD₆₀/D₃₀
- DD₃₀²/(D₁₀ × D₆₀)
Solution
Concept
Uniformity coefficient definition for soil
Formula
Cu = D₆₀/D₁₀
Step-by-step solution
1. The uniformity coefficient (Cu) is a parameter used to express the particle size distribution of a soil. 2. It is mathematically defined as the ratio of particle size corresponding to 60 percent finer (D₆₀) to particle size corresponding to 10 percent finer (D₁₀). 3. Therefore, Uniformity Coefficient Cu = D₆₀/D₁₀. Answer: A
Explanation
The uniformity coefficient (Cu) is defined as the ratio of D₆₀ to D₁₀, where D₆₀ is the particle diameter at 60 percent finer and D₁₀ is at 10 percent finer. It measures the particle size distribution range within a soil mass. A higher value indicates a well-graded soil containing a wide range of grain sizes.
Why the other options are wrong
B) D₃₀/D₁₀ is not the formula for the uniformity coefficient. C) D₆₀/D₃₀ is not the expression used to calculate soil uniformity. D) D₃₀²/(D₁₀ × D₆₀) represents the coefficient of curvature rather than the uniformity coefficient.
Shortcut
Uniformity coefficient formula: Cu = D₆₀/D₁₀ (60 on top, 10 on bottom).
Common mistake
Confusing the formula for Uniformity Coefficient with the formula for Coefficient of Curvature.
Correct answer: A) D₆₀/D₁₀