Drillability in hard rock drill and blast tunnelling

The drillability of a rock mass is determined by various geological and mechanical parameters. In this report some major correlations of specific rock properties as well as geological factors with measured bit wear and drilling rates are shown. Apart from conventional mechanical rock properties (unconfined compressive and tensile strength, Young's modulus) a new property for toughness referring to drillability has been introduced: the specific destruction work W_z. This new property makes it possible to better understand the connection between drilling velocity and the main mechanical rock character.