An improvement to unified size effect law for intact rock

H. Masoumi, A. Arefi, P. Hagan, H. Roshan, M. Sharifzadeh

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3 Citations (Scopus)


While rock strength is an important input parameter in geotechnical engineering, the size effect of intact rock samples on strength has long been recognised as an issue. Conventionally, it has been believed that increase in size leads to decrease in strength. A few investigations have reported different trend to that consider conventionally where the uniaxial compressive strength (UCS) follows ascending and descending behaviour. Masoumi et al. [1] investigated this behaviour from analytical and experimental viewpoints that resulted in the formulation of the unified size effect law (USEL) which accounts for the reverse size effect behaviour of intact rocks. A limitation of the current USEL is that at very large sizes, the UCS prediction by USEL tends to zero. This paper outlines an improvement to USEL to overcome this limitation based on the multifractal theory. Attributes of the improved USEL model were highlighted and verified using UCS data from different rock types. Finally, it was demonstrated that there is a good agreement between the improved USEL prediction and the experimental results.

Original languageEnglish
Title of host publication51st US Rock Mechanics / Geomechanics Symposium 2017
EditorsHaiying Huang
Place of PublicationAlexandria VA USA
PublisherAmerican Rock Mechanics Association (ARMA)
Number of pages6
ISBN (Electronic)9781510857582
Publication statusPublished - 1 Jan 2017
Externally publishedYes
EventUS Rock Mechanics / Geomechanics Symposium 2017 - San Francisco, United States of America
Duration: 25 Jun 201728 Jun 2017
Conference number: 51st


ConferenceUS Rock Mechanics / Geomechanics Symposium 2017
CountryUnited States of America
CitySan Francisco
Internet address

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