Probabilistic Assessment of Standard Penetration Test Hammer Energy Efficiency and Rod Length Corrections

ÇETİN K. Ö., Cevik M. E., Al-Suhaily A., Yunatci A. A.

Journal of Geotechnical and Geoenvironmental Engineering, cilt.149, sa.8, 2023 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 149 Sayı: 8
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1061/jggefk.gteng-11136
  • Dergi Adı: Journal of Geotechnical and Geoenvironmental Engineering
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Applied Science & Technology Source, Aquatic Science & Fisheries Abstracts (ASFA), CAB Abstracts, Compendex, Computer & Applied Sciences, Environment Index, Geobase, ICONDA Bibliographic, INSPEC, Metadex, Pollution Abstracts, Civil Engineering Abstracts
  • Anahtar Kelimeler: Hammer energy efficiency, Probability, Short rod correction, Standard penetration test (SPT)
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Despite the clearly stated procedures in current standards, and contrary to its name, nonstandard execution of the standard penetration test (SPT) has been common. The use of different equipment and procedures produces significantly different SPT blow counts. To minimize the effects of these differences, correction factors are applied. Two of these corrections factors, namely hammer energy efficiency ratio (CE) and rod length (CR) corrections, are the scope of this research study. With the intent of quantifying the effects of variabilities and reducing the uncertainties, SPT hammer efficiency measurements were compiled from available literature. Additionally, new hammer energy measurements were performed in the field, controlling the variables of the problem. The resulting database is used to probabilistically develop a set of new CE and CR recommendations. The recommended mean energy ratios for safety hammer and automatic hammers are estimated as 67%±11% and 78%±12%, respectively, which are higher than typically assumed values in engineering practice. The recommended rod length correction values at shallow depths, proven to be also a function of SPT blowcounts, N (SPT-N) values, are higher than typically used values. This suggests less pronounced rod length effects. Additionally, a modified procedure to assess the stress-wave energy at anvil and above the SPT sampler elevations is introduced.