Issue 42

M. Davydova et alii, Frattura ed Integrità Strutturale, 42 (2017) 170-180; DOI: 10.3221/IGF-ESIS.42.18 179 C ONCLUSION ragmentation of Mansurov granite under quasi-static loading described by power law (Fig.2(b)) in the range of fragment mass from   5 4.5 10 g to 500 g (7 orders). The shape of the fragments changes from splinter (circularity 0.3) to oval (circularity 0.8). The increasing in the circularity and the number of grains with the size equal to about 1mm explains the sharp growth of the fragments number with the size about 1mm. This fact can be caused by chipping of feldspar grains. Thus, it can be concluded that along with the cracking for the formation of small fragments, we have an additional failure mechanism, which is caused by grain disintegration. A CKNOWLEDGMENT e thank our colleagues from Nano-mineralogy Sector of Perm State University who provided the structure study of granite. This work is supported by Russian Foundation for Basic Research, grant 16-41-590-779-p_a. R EFERENCES [1] Turcotte, D. L., Fractals and Chaos in Geology and Geophysics, second ed., Cambridge University Press, (1997). [2] Grady, D.E., Lipkin, J., Criteria for impulsive rock fracture, Geophysical Research Letter, 7(1980) 255-258. DOI: 10.1029/GL007i004p00255. [3] Grady, D.E., Kipp, M.E., Dynamic rock fragmentation, in: B.K. Atkinson (Eds.), Fracture mechanics of rock, Academic Press, London, (1987) 429-475. [4] Bowman, E. T., Dynamic rock fragmentation: thresholds for long runout rock avalanches, Frattura ed Integrità Strutturale, 30 (2014) 7-13. DOI: 10.3221/IGF-ESIS.30.02. [5] Wang, S.R., Li, C.Y., Zou, Z.S., Liu, X.L., Acoustic emission characteristics of instability process of a rock plate under concentrated loading. Avalanches, Frattura ed Integrità Strutturale, 36 (2016) 182-190. DOI: 10.3221/IGF-ESIS.36. [6] Panteleev, I., Plekhov, O., Pankov, I., Evseev, A., Naimark, O., Asanov, V., Experimental investigation of the spatio- temporal localization of deformation and damage in sylvinite specimens under uniaxial tension, Engineering Fracture Mechanics, 129 (2014) 38-44. DOI:10.1016/j.engfracmech.2014.08.004. [7] Vettegren, V.I., Kuksenko, V.S., Shcherbakov, I.P., Dynamics of microcracks and time dependences of surface deformation of a heterogeneous body (granite) under an impact. Physics of the Solid State, 54(7) (2012) 1425-1429. DOI:10.1134/S1063783412070347. [8] Chmel, A., Sherbakov, I., Damage initiation in brittle and ductile materials as revealed from a fractoluminescence study, Frattura ed Integrità Strutturale, 30 (2014) 162-166. DOI: 10.3221/IGF-ESIS.30.21. [9] Kawaguchi, Yo., Charged particle emission and luminescence upon bending fracture of granite, Japanese Journal of Applied Physics, 37(6A) (1998) 3495-3499. DOI: https://doi.org/10.1143/JJAP.37.3495. [10] Panteleev, I., Mubassarova, V., Damaskinskaya, E., Naimark, O., Bogomolov, L., Influence of weak electric field on spatialoral dynamics of damage evolution during granite deformation. AIP Conference Proceedings, 1683 (2015) 020177, DOI: http://dx.doi.org/10.1063/1.4932867. [11] Chen, Yo., Nishiyama, T., Ito, T., Application of image analysis to observe microstructure in sandstone and granite, Resource geology, 51(3) (2001) 249-258. DOI: 10.1111/j.1751-3928.2001.tb00096.x. [12] Kurlenya, M.V., Yakovistskaya, G.E., Kulakov, G.I., Stages in the fracturing process based on EME studies, Journal of Mining Science, 27(1) (1991) 39-43. DOI:10.1007/BF02499684. [13] Kurlenya, M.V., Kulakov, G.I., Yakovitskaya, G.E., Spectral-time analysis of electromagnetic emission during crack formation in ore specimens, Journal of Mining Science, 29(1) (1993) 3 -13. DOI:10.1007/BF00734323. [14] Kulakov, G.I., Yakovitskaya, G.E., Method of predicting the fracture of rocks using the features of the spectral-time characteristics of signals of electromagnetic radiation, Journal of Applied Mechanics and Technical Physics, 36(6) (1995) 928-932. DOI:10.1007/BF02369392. F W