Sarı, Mehmet13.07.20192019-07-1613.07.20192019-07-1620109780415586542https://hdl.handle.net/20.500.12451/2830European Rock Mechanics Symposium, EUROCK 2010 -- 15 June 2010 through 18 June 2010 -- Lausanne -- 89434A very useful approximation for the estimation of the Hoek-Brown material constant mi is presented in this study and the basic logic behind it is evaluated in detail. The study clearly indicates that the Hoek-Brown material constant mi can be approximately predicted from the ratio between the uniaxial compressive strength and tensile strength of brittle intact rocks. By introducing the brittleness ratio of ?c/?t into the generalized Hoek-Brown failure equation instead of the material constant mi , which, actually, has a fundamental importance, a practical formulation is suggested for this commonly employed failure criterion. © 2010 Taylor & Francis Group.eninfo:eu-repo/semantics/closedAccessConference Object169172N/AN/A