Strength Damage and Acoustic Emission Characteristics of Water-Bearing Coal Pillar Dam Samples from Shangwan Mine, China

Yang Wu, Qiangling Yao (), Baoyang Wu, Hongxin Xie (), Liqiang Yu, Yinghu Li and Lujun Wang
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Yang Wu: State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, National Institute of Clean and Low Carbon Energy, Beijing 102211, China
Qiangling Yao: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China
Baoyang Wu: State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, National Institute of Clean and Low Carbon Energy, Beijing 102211, China
Hongxin Xie: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China
Liqiang Yu: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China
Yinghu Li: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China
Lujun Wang: State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, National Institute of Clean and Low Carbon Energy, Beijing 102211, China

Energies, 2023, vol. 16, issue 4, 1-20

Abstract: Long-term erosion and repeated scouring of water significantly affect the technical properties of coals, which are the essential elements that must be considered in evaluating an underground reservoir coal column dam’s standing sustainability. In the paper, the coal pillar dam body of the 2 2 layers of coal in the Shangwan Coal Mine is studied (2 2 represents No. 2 coal seam), and the water content of this coal pillar dam body is simplified into two types of different water content and dry–wet cycle. Through acoustic emission detection technology and energy dissipation analysis method, the internal failure mechanism of coal water action is analyzed. This study revealed three findings. (1) The crest pressure, strain, and resilient modulus in the coal sample were inversely related to the water content along with the dry–wet cycle number, while the drying–wetting cycle process had a certain time effect on the failure to the sample. (2) As the moisture content and the dry–wet cycle times incremented, three features were shown: first, the breakage pattern is the mainly stretching fracture for the coal specimen; second, the number and absolute value of acoustic emission count peaks decrease; third, the RA-AF probability density plot (RA is the ratio of AE Risetime and Amplitude, and AF is the ratio of AE Count and Duration) corresponds more closely to the large-scale destruction characteristics for the coal samples. (3) A higher quantity of wet and dry cycles results in a smoother energy dissipation curve in the compacted and flexible phases of the crack, indicating that this energy is released earlier. The research results can be applied to the long-term sustainability assessment of the dams of coal columns for underground reservoirs and can also serve as valuable content to the excogitation of water-bearing coal column dams under similar engineering conditions.

Keywords: water content; dry–wet cycles; strength damage; acoustic emission; energy dissipation (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: 2023
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