Point Load Strength Index of Half-Cut Core Specimens and Correlation with Uniaxial Compressive Strength

Abstract

The point load strength index is a widely used index in rock engineering, and cylindrical core and irregular shaped specimens are used in its determination. But, in mine sites, the borehole cores are cut axially into two equal parts to obtain half-cut cores and one part of these half cores is sent to laboratory for geochemical analyses. This situation causes a problem that the remaining half of the cores from the specimens cannot be used not only in the strength and deformability tests, but also in the point load test. In this study, it is aimed to investigate the applicability of the point load test on half-cut cores, to adopt the previously suggested size correction formulations to the half-cut core specimens and to estimate the uniaxial compressive strength from the point load strength index determined from the half-core specimens. To achieve these goals, point load strength index and uniaxial compression tests were conducted on a number of half-cut and cylindrical core samples prepared from 12 different rock types and the test results were assessed based on the statistical analyses. The analysis results indicated that the point load strength index may also correctly be determined from the half-cut cores and uniaxial compressive strength may be estimated from the size corrected point load strength index values of half-cut cores with a low error margin using average size correction factor.