FIELD: mining. SUBSTANCE: method involves the steps of: providing specimens with natural or artificial surfaces of weakness such that the surfaces are orthogonal to the end-faces of respective specimens, placing each specimen in matrix 6 such that the surface of weakness coincides with the plane of low-modulus washer 7 interposed between the matrix portions, loading the specimen with the aid of plunger 9 through hydraulic line 13 to stresses corresponding to a stressed state of the specimen in block, increasing pressure in hydraulic line 14 by setting a required shear angle of α with the aid of synchronizer 15 for setting pressure ratio, driving plungers 2 and 3 into action, taking readings of force meters 16 at the moment of breaking the specimen, shear angle for each specimen being maintained constant. EFFECT: reduced man-hours and enhanced reliability in determining strength characteristics due to excluding orientation of surfaces of weakness of weakness in specimens at testing. 4 cl, 3 dwg
