MULTIFRACTAL CHARACTERIZATION OF THE INHOMOGENEOUS STRAIN EVOLUTION OF THE DEHYDRATED COAL: INSIGHT FROM COAL MICROSTRUCTURE

Junjun Feng, Chuanhua Xu, Feng Yu, Jun Peng, Qisong Huang and Peng Jin
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Junjun Feng: Sinosteel Maanshan General Institute of Mining Research Co., Ltd., Maanshan 243000, P. R. China†State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, Jiangsu 221116, P. R. China‡Civil Engineering and Architecture, Anhui University of Technology, Maanshan, Anhui 243000, P. R. China§Key Laboratory of Green Construction and Safety, Anhui University of Technology, Maanshan, Anhui 243002, P. R. China
Chuanhua Xu: Sinosteel Maanshan General Institute of Mining Research Co., Ltd., Maanshan 243000, P. R. China
Feng Yu: ��Civil Engineering and Architecture, Anhui University of Technology, Maanshan, Anhui 243000, P. R. China
Jun Peng: Sinosteel Maanshan General Institute of Mining Research Co., Ltd., Maanshan 243000, P. R. China
Qisong Huang: Sinosteel Maanshan General Institute of Mining Research Co., Ltd., Maanshan 243000, P. R. China‡Civil Engineering and Architecture, Anhui University of Technology, Maanshan, Anhui 243000, P. R. China§Key Laboratory of Green Construction and Safety, Anhui University of Technology, Maanshan, Anhui 243002, P. R. China
Peng Jin: ��Civil Engineering and Architecture, Anhui University of Technology, Maanshan, Anhui 243000, P. R. China

FRACTALS (fractals), 2024, vol. 32, issue 02, 1-28

Abstract: Underground coal mining in China has gradually moved into deeper seams in recent years, which results in a higher ambient temperature in the mining space and significantly affects the mechanical behavior of coal. In this study, dehydrated coal samples were obtained at different temperatures ranging from 30∘ to 70∘, and the mechanical behavior of the dehydrated coal was investigated through compressive loading tests. The digital image correlation (DIC) method was used to acquire the strain field of coal, and a multifractal analysis was conducted to characterize the strain evolution of coal. The findings suggest that the increasing temperatures result in higher moisture desorption rates and greater volumetric contraction strain in coal. Furthermore, coal with higher moisture desorption exhibits higher peak stress and peak strains when subjected to compressive loading. The multifractal analysis of the inhomogeneous strain evolution indicates a gradual decrease in the parameter Δα under compressive loading, followed by a sudden increase before reaching the failure point due to strain localization. The multifractal mechanism was further investigated, revealing that the inhomogeneous strain field of coal is inherently affected by the microstructure of coal. In addition, a mathematical model was proposed to elucidate the relationship between the inhomogeneous coal strain and the microstructure of coal. The result indicates that the inhomogeneity of the coal strain is directly associated with the multifractal singularity of the coal microstructure. Finally, the feasibility of using the multifractal parameter Δα to identify coal strain localization has been demonstrated, indicating its potential value in aiding engineers to determine the SLZ in deep coal mines.

Keywords: Multifractal Analysis; Inhomogeneous Strain; Digital Image Correlation; Coal Microstructure; Strain Localization (search for similar items in EconPapers)
Date: 2024
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DOI: 10.1142/S0218348X24500361

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