Correlation study between indentation indices and physical-mechanical properties of rocks

Indentation test is one of the laboratory approaches that is used to predict the performance of Raise Boring Machines (RBMs) and Tunnel Boring Machines (TBMs). This test is a nonstandard laboratory experiment that was originally developed to provide a method to predict the normal force acting on the cutters used on mechanical miners. However, in some cases due to difficulties in obtaining rock samples as well as insufficient laboratory equipment it is not possible to perform indentation test. In this study, based on the indentation tests on different rock samples obtained from raise-boring projects in Turkey, three indentation indices (brittleness indices and force index) are obtained; then, the multi-variable correlations between these indices and physical-mechanical properties of rocks are investigated. The study indicates that all three indentation indices can be estimated by using the velocity of P-wave, static elasticity modulus, Cerchar abrasivity index, and Schmidt hammer hardness of rocks.