Quantifying Rock Strength Variability Under Different Tests and Failure Modes.
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| Title: | Quantifying Rock Strength Variability Under Different Tests and Failure Modes. |
|---|---|
| Authors: | Butcher, Clarence1 (AUTHOR), Buzzi, Olivier1 (AUTHOR) Olivier.Buzzi@newcastle.edu.au |
| Source: | Rock Mechanics & Rock Engineering. Feb2026, Vol. 59 Issue 2, p1441-1454. 14p. |
| Subject Terms: | *Compressive strength, *Rock testing, *Rock properties, *Slope stability, *Testing laboratories |
| Abstract: | The influence of rock strength variability on discontinuity stability is often not considered, because slope stability and discontinuity shear strength models generally assume uniform strength conditions. In addition, a lack of budget and access to material often restricts engineers from adequately characterising rock variability with extensive laboratory testing. The strength of rock is highly variable, and slope stability analysis must account for variability for accuracy, and to minimise over-conservativism in design. An extensive laboratory testing regime comprised of unconfined and triaxial compressive strength tests, Schmidt hammer tests, and tilt tests was conducted on three rock types: a limestone, a sandstone, and a granite. The purpose of extensively testing these materials was to compare the variability of each test type to find economic methods for determining variability, and to compare how different tests react to material strength variability. The Schmidt hammer and tilt tests were found to be useful tests to predict the variability of UCS tests and triaxial tests at high confining stress, respectively. The variability of triaxial compressive strength was observed to decrease as the failure mechanism transitioned from brittle failure to the transition zone of brittle–ductile failure when confining stress had increased sufficiently. Whilst some parameters' variability was characterised with many tests, the variability of the Hoek–Brown intact material constant was determined by a statistical bootstrap analysis of a single data set. Finally, a brief review of current literature found that the basic friction angle, the Hoek–Brown intact compressive strength, and the Hoek–Brown intact material constant can be assumed to be independent of each other during slope stability analysis, where extensive site-specific calibration or tensile testing cannot validate any relationship between each parameter. Highlights: The variability of tilt-tests, Schmidt hammer tests, unconfined compression tests, and triaxial tests were investigated. A statistical bootstrap analysis was performed on a limestone material to determine the variability of the Hoek–Brown intact materials constant, mi. The minimum number of tests to characterise variability was determined for the Schmidt hammer, tilt-test, triaxial test, and unconfined compressive strength test. The Schmidt hammer test and tilt-test were found to be acceptable proxy tests to characterise the variability of unconfined and confined compressive strengths of rock, respectively. In-situ stress values and possible brittle response should be considered when selecting a proxy test to characterise variability. [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 191692996 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Quantifying Rock Strength Variability Under Different Tests and Failure Modes. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Butcher%2C+Clarence%22">Butcher, Clarence</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Buzzi%2C+Olivier%22">Buzzi, Olivier</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> Olivier.Buzzi@newcastle.edu.au</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Rock+Mechanics+%26+Rock+Engineering%22">Rock Mechanics & Rock Engineering</searchLink>. Feb2026, Vol. 59 Issue 2, p1441-1454. 14p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Compressive+strength%22">Compressive strength</searchLink><br />*<searchLink fieldCode="DE" term="%22Rock+testing%22">Rock testing</searchLink><br />*<searchLink fieldCode="DE" term="%22Rock+properties%22">Rock properties</searchLink><br />*<searchLink fieldCode="DE" term="%22Slope+stability%22">Slope stability</searchLink><br />*<searchLink fieldCode="DE" term="%22Testing+laboratories%22">Testing laboratories</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The influence of rock strength variability on discontinuity stability is often not considered, because slope stability and discontinuity shear strength models generally assume uniform strength conditions. In addition, a lack of budget and access to material often restricts engineers from adequately characterising rock variability with extensive laboratory testing. The strength of rock is highly variable, and slope stability analysis must account for variability for accuracy, and to minimise over-conservativism in design. An extensive laboratory testing regime comprised of unconfined and triaxial compressive strength tests, Schmidt hammer tests, and tilt tests was conducted on three rock types: a limestone, a sandstone, and a granite. The purpose of extensively testing these materials was to compare the variability of each test type to find economic methods for determining variability, and to compare how different tests react to material strength variability. The Schmidt hammer and tilt tests were found to be useful tests to predict the variability of UCS tests and triaxial tests at high confining stress, respectively. The variability of triaxial compressive strength was observed to decrease as the failure mechanism transitioned from brittle failure to the transition zone of brittle–ductile failure when confining stress had increased sufficiently. Whilst some parameters' variability was characterised with many tests, the variability of the Hoek–Brown intact material constant was determined by a statistical bootstrap analysis of a single data set. Finally, a brief review of current literature found that the basic friction angle, the Hoek–Brown intact compressive strength, and the Hoek–Brown intact material constant can be assumed to be independent of each other during slope stability analysis, where extensive site-specific calibration or tensile testing cannot validate any relationship between each parameter. Highlights: The variability of tilt-tests, Schmidt hammer tests, unconfined compression tests, and triaxial tests were investigated. A statistical bootstrap analysis was performed on a limestone material to determine the variability of the Hoek–Brown intact materials constant, mi. The minimum number of tests to characterise variability was determined for the Schmidt hammer, tilt-test, triaxial test, and unconfined compressive strength test. The Schmidt hammer test and tilt-test were found to be acceptable proxy tests to characterise the variability of unconfined and confined compressive strengths of rock, respectively. In-situ stress values and possible brittle response should be considered when selecting a proxy test to characterise variability. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1007/s00603-025-04952-4 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 14 StartPage: 1441 Subjects: – SubjectFull: Compressive strength Type: general – SubjectFull: Rock testing Type: general – SubjectFull: Rock properties Type: general – SubjectFull: Slope stability Type: general – SubjectFull: Testing laboratories Type: general Titles: – TitleFull: Quantifying Rock Strength Variability Under Different Tests and Failure Modes. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Butcher, Clarence – PersonEntity: Name: NameFull: Buzzi, Olivier IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 02 Text: Feb2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 07232632 Numbering: – Type: volume Value: 59 – Type: issue Value: 2 Titles: – TitleFull: Rock Mechanics & Rock Engineering Type: main |
| ResultId | 1 |
