Universal criteria for rock brittleness estimation under triaxial compression

摘要: Abstract Brittleness is one of the most important mechanical properties rock; however, concept brittleness in rock mechanics yet to be precisely defined. Many criteria have been proposed characterise material behaviour under compression, but there no consensus as which suitable and reliable. This paper considers at compression capability self-sustaining macroscopic failure post-peak region due elastic energy accumulated within loaded material. The applicability various for assessing from this point view analysed. It shown that only two many existing can describe properly intrinsic whole range variation absolute ductility. These rely upon balance are based on sound physics principles. Unlike other they allow representation classes (Class I Class II) form continuous, monotonic unambiguous scale brittleness. effect confining pressure analysed where changed II then again.