Abstract
The point load index (PLI) test is one of the most frequently applied indirect methods in predicting the uniaxial compressive strength (UCS). Depending on the rock sample shape, the PLI test is performed in four procedures: axial, diametrical, block, and irregular lump tests. The present research aims to conduct a comparative study on the accuracy of these four procedures in predicting the UCS and evaluate the effect of density (ρ) and porosity (n) on the correlation between UCS and PLI. For this purpose, 15 different sandstone samples were collected from north Khorramabad, west of Iran. Some sandstone specimens were prepared for ρ, n, UCS, and PLI tests. Results indicated that PLI procedures have different accuracies in predicting the UCS, such that axial and irregular lump tests have the highest (R2 = 0.85) and the lowest (R2 = 0.70) accuracies, respectively. Moreover, the results of multivariate regression analysis revealed that n compared to ρ has a more important effect on the correlation between UCS and PLI (R2 = 0.87 and 0.92, respectively).
Highlights
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Depending on the rock sample shape, the point load index test (PLI) is performed in four procedures: axial, diametrical, block, and irregular lump tests.
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The accuracy of procedures proposed for four PLI tests in predicting the uniaxial compressive strength (UCS) for sandstone samples is investigated.
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This study also aims to evaluate the effect of density (ρ) and porosity (n) on the correlation between UCS and PLI.
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The PLI procedures have different accuracies in predicting the UCS, such that axial test has the highest accuracy.
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The multivariate regression analyses revealed that n compared to ρ has a more important effect on the correlation between UCS and PLI.
Abbreviations
- UCS:
-
Uniaxial compressive strength
- PLI:
-
Point load index
- ρ :
-
Density
- n :
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Porosity
- R 2 :
-
Determination coefficient
- SEE:
-
Standard error of estimate
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Acknowledgements
The author would like to acknowledge the financial support of Lorestan University for this research under grant number “1400403331401”.
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Jamshidi, A. A Comparative Study of Point Load Index Test Procedures in Predicting the Uniaxial Compressive Strength of Sandstones. Rock Mech Rock Eng 55, 4507–4516 (2022). https://doi.org/10.1007/s00603-022-02877-w
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DOI: https://doi.org/10.1007/s00603-022-02877-w