Nokta Yükü Dayanım İndeksinin Yarılanmış Karot Örneklerinden Belirlenebilirliğinin Araştırılması

Abstract

The point load strength index is a widely used index for classifying rocks according to their strengths and estimating the uniaxial compressive strength. This index is determined by the point load test on cylindrical core specimens or irregular shaped specimens. But the cores taken from the mine sites are cut axially into two equal parts to obtain half-split cores and one part is sent to the laboratory to be subjected to geochemical analyzes in order to determine the quality of the ore. This situation causes the problem that the remaining half 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 strength index test on half-split core samples and to suggest an empirical equation for indirectly estimating the uniaxial compressive strength from the values of point load strength index determined in this way. For this purpose, a large number of cylindrical and half-split core specimens were prepared at different diameters from 12 different unweathered rock types compiled from different sites. The point load strength index test was performed on the half-split core specimens, while both point load and uniaxial compressive strength tests were performed on the cylindrical core specimens. A statistically significant and linear empirical relationship, with a very high correlation coefficient, between the results of the point load strength index of the cylindrical specimens and those of the half-split core specimens was found. In addition, it was also found that the empirical relationship, based on the statistical analyses and the values of point load strength index, which were determined from the point load tests carried out on the half-split core specimens, estimates uniaxial compressive strength values better than the empirical equation based on the point load strength index determined from cylindrical specimens. As a result of this study, it is understood that the point load strength index can also be determined from half-split core specimens and the uniaxial compressive strength can be indirectly estimated from this value, which is determined from the half-split core specimen, with a low error margin by multiplying it by a conversion coefficient.