About features of ultrasonic measurements in coal samples using shear elastic waves

The use of shear elastic waves of the ultrasonic frequency range in the study of the structure and properties of rocks makes it possible to increase the sensitivity of control, and also allows to evaluate the anisotropy of the geomaterial and to identify oriented defects in it. However, in comparison with traditionally used longitudinal waves, the use of shear waves is associated with a number of difficulties, both at the stage of their generation and at the stages of their introduction into the controlled medium and reception from it. This is especially true when working with brittle, porous and fractured rocks with large attenuation of elastic waves, such as coal. Laboratory studies were conducted on samples of anthracite, hard coal and lignite. It is shown that the use of highly viscous liquid contact media, such as honey, allows one to stably register shear waves in coal samples. However, repeated use of such media leads to their penetration into the surface layer of the sample and a gradual change in its acoustic properties and damage degree. It is proposed to use sandpaper of various grain sizes to introduce and receive the shear waves into and from controlled object. Sandpaper is glued to the protector of the acoustic transducer. For various types of coals, optimal grit sizes of sandpaper have been established providing the maximum signal/noise ratio. It is shown that use of such contact medium during repeated measurements does not reduce the quality of acoustic contact and does not affect the results of ultrasonic studies.

Keywords: ultrasonic measurements, shear wave, anthracite, hard coal, lignite, properties, contact conditions.
For citation:

Skuratnik V. L., Nikolenko P. V., Anufrenkova P. S. About features of ultrasonic measurements in coal samples using shear elastic waves. MIAB. Mining Inf. Anal. Bull. 2020;(4):117-126. [In Russ]. DOI: 10.25018/0236-1493-2020-4-0-117-126.

Acknowledgements:

This work was financially supported by the Russian Foundation for Basic Research, No. 18-05-70002.

Issue number: 4
Year: 2020
Page number: 117-126
ISBN: 0236-1493
UDK: 622.02: 539.2
DOI: 10.25018/0236-1493-2020-4-0-117-126
Article receipt date: 24.01.2020
Date of review receipt: 21.02.2020
Date of the editorial board′s decision on the article′s publishing: 20.03.2020
About authors:

V.L. Skuratnik1, Dr. Sci. (Eng.), Professor, e-mail: ftkp@mail.ru,
P.V. Nikolenko1, Cand. Sci. (Eng.), Assistant Professor, e-mail: petrov-87@mail.ru,
P.S. Anufrenkova1, Graduate Student,
1 National University of Science and Technology «MISiS», 119049, Moscow, Russia.

 

For contacts:

V.L. Skuratnik, e-mail: ftkp@mail.ru.

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