A method of measuring rock
fracture toughness with Brazilian disc specimen having a central hole is suggested.First,the
sufficient condition for the specimen fracture initiating at the intersection point between the loading diameter and the edge of the central hole is determined according to Griffith fracture criterion;then the maximal dimensionless stress intensity factor ( Y max ) of Brazilian disc specimen with a newly cut flat surface at two opposite sides is calibrated by 2 D BEM;and the minimal load value ( P min ) is obtained from load vs load point displacement curve;thus the method for
measuring rock
fracture toughness is established.A lime rock fracture toughness is estimated by this method coincides satisfactorily with the standard value ( K ⅠC ) determined by a chevron notch specimen method recommended by International Society for Rock Mechanics(ISRM).Furthermore,this method can effectively measure the fracture toughness of isotropic rock materials.