Rock strength determination from scratch tests

Thomas Richard, Fabrice Dagrain, Edmond Poyol, Emmanuel Detournay

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


This paper provides compelling experimental evidence that the unconfined compressive strength of rocks can be reliably assessed from scratch tests performed with a sharp cutter, and at depth of cut small enough to prevent any significant chipping of the rock. The paper describes the model used to interpret the experimental results, the test methodology, and the Rock Strength Device that was developed to perform scratch tests under kinematically controlled conditions. It concludes with a summary of an extensive experimental campaign involving the testing of several hundred rocks to compare strength data from conventional uniaxial compression experiments and from scratch tests.

Original languageEnglish (US)
Pages (from-to)91-100
Number of pages10
JournalEngineering Geology
StatePublished - Oct 12 2012

Bibliographical note

Funding Information:
Many people have contributed to the development of the scratch test to measure the strength of rocks and to the design of the RSD. Their contributions are gratefully acknowledged, with the authors being particularly indebted towards Robert Delwiche, Andrew Drescher, Erling Fjaer, David Hultman, Cécile Lasserre, and Tanguy Lhomme for their help. The research was funded by grants from the Sota Tec Fund , Elf Aquitaine , Total , and DBS .


  • Cutting test
  • Experiments
  • Strength log
  • Uniaxial compressive strength


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