Experimental Study of Creep Acoustic Emission Characteristics of Coal Bodies around Boreholes under Different Moisture Contents

Tianjun Zhang, Zhiqiang Ling, Mingkun Pang and Yukai Meng
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Tianjun Zhang: College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Zhiqiang Ling: College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Mingkun Pang: College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Yukai Meng: College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China

Energies, 2021, vol. 14, issue 11, 1-13

Abstract: Water content is an important factor in the deformation-destruction process of coal bodies. To analyze the influence of water on the creep acoustic emission (AE) characteristics of coal rock surrounding a borehole, we conducted graded loading creep AE tests of single-hole specimens with different water contents (0%, 4%, 8% and water-saturation) under uniaxial loading. The findings include the following: the water content affects the creep mechanical properties of the coal body around a borehole. The creep transient strain and steady-state strain increased exponentially with rising water content; the saturated specimen showed the highest increase, reaching 44.5% and 28.6%, respectively. The specimen water content affected the cumulative ringing count (CRC) and the axial strain during creep. The axial strain increased with rising water content, the CRC increased linearly with rising axial strain. The higher the water content, the greater the CRC rise. At different stress levels, the CRC in the 4%, 8% and saturated water content specimens changed by 43%, 53% and 74%, respectively. The AE ringing rate showed a pattern of grow–decline–stabilize at each creep stage. The AEs decreased significantly with the rising water content and the creep curve lagged behind the AE data. This paper provides guidelines for gas extraction, borehole maintenance and AE detection.

Keywords: creep test; porous coal body; water content; cumulative ringing count; energy (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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