PSI - Issue 32

Ivan Pankov et al. / Procedia Structural Integrity 32 (2021) 166–172 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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destroyed samples after the tests, are presented in Fig. 1. The test for the biaxial compression has been conducted as illustrated by a drawing in paper (Arora and Mishra, 2015). a b c

Fig. 1. Drawings of tests and the characteristic appearance of destroyed samples during a complex rock strength determination: (a) is the uniaxial tensile (the Brasil method); (b) is the uniaxial compression; (c) is the biaxial compression The values of the principal stresses corresponding to the rock destruction with different load patterns are: - uniaxial tensile ͳ ൌ ʹ ൌ Ͳǡ ͵ ൌ Ǣ ሺͳሻ - uniaxial compression ͳ ൌ ͳ ǡ ʹ ൌ ͵ ൌ ͲǢ ሺʹሻ - biaxial compression ͳ ൌ ʹ ൌ ʹ ǡ ͵ ൌ ͲǤ ሺ͵ሻ As can be seen from Fig. 1, the manner in which the samples are destroyed is determined by an influence of a deformation transverse to the applied load in the direction of the free surface. 3. Rock Strength Criterion According to the selected test diagrams during the complex rock strength indicator determination, the general form of the strength criterion has been written as the following equation: ͳ ͳ ൌ А ൅ ʹ ʹ ൅ ͵ ͵ ǡ ሺͶሻ