ISSN 1062-7391, Journal of Mining Science, 2017, Vol. 53, No. 5, pp. 818–823. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © V.L. Shkuratnik, P. V. Nikolenko, and A.E. Koshelev, 2017, published in Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh
Iskopaemykh, 2017, No. 5, pp. 23–28.
_________________________________ GEOMECHANICS _______________________________
Spectral Characteristics of Acoustic Emission
in Loaded Coal Specimens for Failure Prediction
V. L. Shkuratnik
, P. V. Nikolenko
, and A. E. Koshelev
Academician Melnikov Institute of Integrated Mineral Resources Development—IPKON,
Russian Academy of Sciences, Moscow, 111020 Russia
Gazprom geotekhnologii, Moscow, 119311 Russia
Received August 30, 2017
Abstract—Сhanges in acoustic emission spectra of coal samples from the Kuznetsk and Pechora Basins are
experimentally studied in uniaxial and triaxial (Karman-type) compression tests. It is shown that the
acoustic emission spectral patterns change considerably at the pre-failure stage in the samples under uniaxial
compression: the amplitudes of low-frequency components grow while those of high frequencies reduce.
Under the Karman-type compression, the amplitudes of low-frequency signals grow while the high-
frequency amplitudes do not change much, because lateral hydrostatic pressure impedes opening of vertical
Keywords: Coal, acoustic emission, specimen, spectrum, uniaxial and triaxial loading, Kuznetsk and
Pechora Coal Basins.
The stability of natural and engineering objects depends on the stress–strain interaction [1–3],
which has to be taken into account in prediction of dynamic hazards and in choice of engineering
solutions for stability management. This management is impossible without reliable knowledge of
stress and strain variations in space and time under natural and industrial loads on natural or manmade
materials. Currently, much experience has been gained in stress and strain measurements by
geophysical methods, especially acoustic emission [4–6].
Acoustic emission (AE) surveys in coal basins require reference to a priori constraints on
measurable parameters of acoustic responses from loaded coal. These parameters are commonly
measured by controlled-source or acoustic-emission methods in coal samples subject to test mechanic
loading in different modes. Most of known empirical relationships represent stress dependence of
velocities and attenuation of compressional (P) waves, or less often shear (S) waves [7–10]. Such
empirical relationships have been obtained for acoustic emission activity [11–16], a parameter
showing the number of single events of fracture initiation and growth which, however, gives no
information on the sizes of fractures. A qualitative idea of fracture sizes can be obtained from AE
spectra [17, 18], for which some methods are suggested in this paper. The respective results are
discussed for cases of test uniaxial and triaxial compression of coal samples from different basins.
LOADING TESTS: PROCEDURE AND RESULTS
Four groups (I–IV) of coal samples were tested. Coal from groups I and II was sampled in the
Boldyrevskiy coal bed, Kirov mine, Kuznetsk Coal Basin and from groups II and IV—in the Troinoi