Question

Consider the following statements:
1. The standard penetration test is a reliable method for measuring the relative density of granular soils.
2. For a sand having the same relative density, N-values remain the same at all depths.
3. For a sand having the same relative density, N-values are different at different depths.
Which of these statements is/are correct?

• A. 1, 2 and 3
• B. 1 and 3
• C. 3 only
• D. 1 and 3

Answer 1

The correct option is C 3 only

SPT is not considered to be a refined and completely reliable method of investigation. The N values give useful information about relative density of cohesionless soils. Thus it does not measure relative density rather correlate N values with relative density.
N values increases with depth due to overburden pressure for sand having same relative density.
Therefore overburden pressure correction are applied.