Dilatancy correction for obtaining corrected SPT blow count is applicable for
- Afine sand and silt below water table with N > 15Correct
- Bsoft clay below water table with N > 15
- Cfine sand and silt above water table with N > 15
- Dnone of the above
Solution
Concept
Dilatancy correction
Formula
N′ = 15 + (N − 15)/2
Step-by-step solution
1. Applied to fine sand and silt below water table when N > 15.
Explanation
Pore pressure builds up in fine saturated sand, so N is reduced.
Why the other options are wrong
Clay or dry soil does not need it.
Shortcut
Fine sand + WT + N>15.
Correct answer: A) fine sand and silt below water table with N > 15