Question

In a soil investigation work at a site, Standard penetration test (SPT) was conducted at every 1.5m interval up to 30m depth. At 3 m depth, the observed number of hammer blows for three successive 150 mm penetration were 8, 6 and 9, respectively. The SPT N-value at 3 m depth, is

• A.
  15
• B.
  23
• C.
  14
• D.
  17

Answer 1

The correct option is A

15
The SPT value is taken as last 300 mm so neglect the SPT of first 150mm
so, SPT $N-$ value at 3 m depth = 6 + 9 = 15