The effect of rock classes on the relation between uniaxial compressive strength and point load index

Uniaxial compressive strength and point load tests were carried out on 17 igneous, 16 metamorphic and 19 sedimentary rocks and the values correlated with their I _s values. The influence of the different rock type was investigated using regression analysis and the derived equations were statistically tested. Although the derived equation for all data is significant, the data points are scattered and the coefficient of correlation is not strong. However, when the regression analysis was repeated for igneous, metamorphic and sedimentary rocks respectively, the data were less scattered and stronger correlation coefficients were obtained.