Summary
Our investigations have established that the scale factor greatly changes the strength characteristics of anthracite both in the case of tests under uniaxial compression and with indentation of a cylindrical flat-based punch, which is accompanied by volume compression.
For both cases we established a stagewise change in the strength characteristics, due to the distinctive effect of the jointing on the properties of anthracite.
To solve problems of rock pressure and the support of workings, it is desirable to use large samples for determining the strength of anthracite in uniaxial compression tests (the size should be sufficient to come within the range of partial stabilization of anthracite strength).
Anthracite samples of diameter and height 40 mm (S=12.5 cm2) are unsuitable for determining the strength of anthracite in uniaxial compression because they fall within the range in which the strength changes markedly with a small change in size of the sample. For tests in uniaxial compression, it is desirable to use anthracite samples of surface area 50–60 cm2 because they give more reproducible results.
In the case of strength determinations by punch indentation, the test procedure should vary in accordance with the purpose of the test. The strength properties of unfissured anthracite (in the areas between the microfissures) should be determined by indentation of a punch with an area of 0.25 mm2, and in the case of anthracite as a whole (with the microfissures) by that of a punch with an area not less than 10 mm2.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Literature Cited
M. I. Koifman, S. E. Chirkov, et al., Effect of sample size and anisotropy on the strengths of some Donbass and Kuzbass coals, In: The Mechanical Properties of Rocks [in Russian], Izd-vo AN SSSR, Moscow (1963).
M. I. Koifman, Studies of the scale factor in rock-pressure research, In: The Mechanical Properties of Rocks [in Russian], Izd-vo AN SSSR, Moscow (1963).
M. M. Protod'yakonov, On the Cutting of Coal and Rocks, Izv. Akad. Nauk SSSR, OTN, No. 11 (1948).
M. M. Protod'yakonov, M. I. Koifman, et al., The Strength Characteristics of Rocks and Methods for Their Determination [in Russian], Nauka, Moscow (1964).
L. A. Shreiner, A. New Method for Determining the Hardness and Drillability of Rocks, Dokl. Akad. Nauk SSSR,46, No. 3 (1942).
L. A. Shreiner, The Mechanical and Abrasive Properties of Rocks [in Russian], Gostoptekhizdat, Moscow (1958).
I. I. Ammosov and I. V. Eremin, The Fissurability of Coals [in Russian], Izd. AN SSSR, Moscow (1960).
G. A. Ivanov, Cleavage (jointing) in Coal and the Surrounding Rock and Methods for Its Practical Utilization, Tr. TsNIGRI,1, No. 110, Izd. GONTI, Moscow (1939).
N. V. Polyakov, A. A. Lapin, and V. Ya. Posyl'nyi, The Water Permeability of Anthracite and Bituminous Coals of the Southeast Donbass, Tr. Shakht NIUI, Izd. Shakht NIUI, Shakhty (1961).
S. E. Chirkov, Studies of the Effect of the Scale Factor on the Strength of Coal in Different Stressed States, Author's Abstract of Dissertation [in Russian], Izd. IGD im. A. A. Skochinskogo, Moscow (1965).
M. M. Krushchov and E. S. Berkovich, The PMT-2 and PMT-3 Microhardness Testers [in Russian], Izd. AN SSSR, Moscow (1950).
Additional information
Shakhty Scientific Research Coal Institute, Shakhty (Rostov Region). Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 30–36, January–February, 1968.
Rights and permissions
About this article
Cite this article
Posyl'nyi, V.Y., Ship-Stafurin, V.V. Effect of dimensions on the strength properties of anthracite. Soviet Mining Science 4, 22–26 (1968). https://doi.org/10.1007/BF02501979
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF02501979