Point-load strength: An index for classification of rock material

  • D. K. Ghosh
  • M. Srivastava


Point-load strength (Is) as a measure for the determination of rock strength and for estimating uniaxial (unconfined) compressive strength (UCS) are described and both put together and used for rock strength classification of brittle and hard rocks.

The estimated point-load strength values of specimens of varying sizes and also the values corrected to a standard thickness of 50 mm, and the resultant point-load strength values (Is-50) have been used to estimate the uniaxial (unconfined) compressive strength which correlates well with actual recorded uniaxial (unconfined) compression test results. Using graphical and mathematical relationships between the observed and estimated UCS and Is values, a conversion factor of 16 is obtained for estimating uniaxial (unconfined) compressive strength values from point load strength results. A nomogram for computing point-load strength index and a system for the classification of rock material are presented.


Compressive Strength Uniaxial Compressive Strength Failure Load Rock Material Rock Strength 

Résistance au fendage sous charge ponctuelle: Un critère de classification pour les roches


La résistance au fendage sous charge ponctuelle (ls) constitue une évaluation de la résistance de la roche et permet d'estimer le résistance en compression uniaxiale (UCS); les deux essais sont utilisés pour établir une classification des roches résistantes de type fragile.

Les valeurs de résistance au fendage sous charge ponctuelle réalisées sur des échantillons de différentes tailles, ainsi que les valeurs ramenées par correction à une épaisseur standard de 50 mm fournissent un valeur résultante ls-50 qui a été utilisée pour estimer la résistance en compression uniaxiale avec une bonne corrélation.

En utilisant des comparaisons graphiques et mathématiques entre les valeurs UCS et ls, un facteur de conversion de 16 est obtenu pour avoir la valeur UCS à partir de la valeur ls. Un nomogramme pour calculer la valeur de résistance au fendage sous charge ponctuelle, et un système de classification des roches son présentés.


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Copyright information

© International Association of Engineering Geology 1991

Authors and Affiliations

  • D. K. Ghosh
  • M. Srivastava
    • 1
  1. 1.Geology DepartmentLucknow UniversityLucknowIndia

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