CORRECTION RELATIONSHIP OF UNIAXIAL COMPRESSIVE BREAKAGE STRENGTH DEPENDING ON THE SCALE EFFECT

ABSTRACT

It is a certainty that a rock massif is a very complex environment, known only partially; in the laboratory we cannot produce all the details encountered in situ; therefore, most of the properties determined experimentally not fully express their real value that they have in rock massif. As theoretical basis we might consider theory of similitude initiated by Newton, in the sense of similarity that we can establish to the boundary between theory and experiment. Based on this and considering the applicable theorems that define main properties and recognition criteria of phenomena to different scales to which material systems are analyzed and implicitly rocks, we have studied the variation manner of rock characteristics established on specimens of different shapes and sizes. This paper presents the influence of scale effect under mechanical characteristics of rocks, as result of studies realized on both cubical and cylindrical specimens. Increasing of geometric dimensions of the specimen involves a higher degree of inhomogeneity of rocks as regards the presence of discontinuities in specimens mass. An own calculation relationship of compressive breakage strength when the specimens cannot be performed to the diameter of 50 mm and for a slenderness ratio equal to 2, it is also proposed.

Keywords: scale effect, strength, slenderness ratio, inhomogeneity, compressive, tensile, cohesion