Determination of the effects of mineralogy on the point load compressive strength of rock

ABSTRACT: Rock forming minerals are of great importance understanding the instability of a rock. While the rock instability has been the main subject of many studies, the relation between rock forming minerals and geomechanical parameters of rock remained unknown. This research study aims to investigate the effect of rock forming minerals on the point load test (PLT) of the rock. In the laboratory, rock specimens from four boreholes with different lithologies are tested to obtain their axial and diametrical PLT. Correspondingly, the mineral of rock specimens is analyzed in thin section study. Here, the thin section results of specimens are coupled with all units of boreholes to assign the obtained minerals to all lithologies of boreholes. As there are many minerals in the database, the principal component analysis (PCA) is applied to reveal the significant minerals and then, the data reduction is carried out. The principal component regression (PCR) is performed to evaluate the effect of minerals on axial and diametrical PLT of the rock. Comparison of PCR results of diametrical and axial PLT highlights the effect of major rock minerals, metamorphic minerals and sheets minerals on PLT. Quartz, feldspar, amphibole, plagioclase, and epidote have shown a positive effect on axial and diametrical PLT of the rock. On the other side, chlorite and white mica have represented a negative effect on axial and diametrical PLT of rock. Moreover, the effect of anisotropy of rock and grain size have shown a negative effect on diametrical PLT of the rock.