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GATE 2020 CE (CE1) – Question 21

Geotechnical Engineering · Sub-surface investigations: boring, SPT, CPT, plate load test · 1 mark · Multiple choice

SPT is performed every 1.5 m to 30 m depth. At depth 3 m, blows for three successive 150 mm penetrations are 8, 6 and 9. Find recorded N at 3 m.

  1. 23
  2. 17
  3. 15
  4. 14

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Correct answer: (C) 15

Explanation

Discard the first 150 mm seating penetration. The recorded value is the sum for the next 300 mm: $N=6+9=15$. **C**.