Effect of secondary impacts on SPT rod energy and sampler penetration

Changho Lee, Jong Sub Lee, Shinwhan An, Woojin Lee

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

This paper explores the standard penetration test (SPT) hammer-anvil behavior and investigates the effect of secondary impact on SPT energy and sampler penetration. It is observed that the hammer-anvil behavior after the impact depends on the characteristics of the wave reflected from the sampler. The type-I secondary impact, which is dominant for N<25, is induced due to the rapid downward movement of the anvil and the recontact of the following hammer on the rebounding anvil. The maximum energy calculated by integrating force and velocity (EFV) is achieved immediately after the occurrence of the type-I secondary impact and an additional sampler penetration is triggered by the type-I secondary impact. The type-II secondary impact, which is dominant for N>50, is produced by the restrike of the pushed-up hammer on the resting anvil. The type-II secondary impact causes only recoverable anvil deformation and does not contribute to the maximum EFV energy. For N-values of 25-50, both or either types of secondary impacts happen. As N-value increases, the type-I secondary impact fade away progressively and the type-II secondary impact becomes more distinctive.

Original languageEnglish
Article number004003QGT
Pages (from-to)522-526
Number of pages5
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume136
Issue number3
DOIs
Publication statusPublished - 2010 Mar

Keywords

  • Energy transfer ratio
  • Standard penetration test (SPT)

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Environmental Science(all)

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