Study on Damage Characteristics of Water-Bearing Coal Samples under Cyclic Loading–Unloading

Hongxin Xie, Qiangling Yao, Liqiang Yu and Changhao Shan
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Hongxin Xie: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China
Qiangling Yao: 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
Changhao Shan: School of Mines, China University of Mining and Technology, No. 1 University Rd., Xuzhou 221116, China

Sustainability, 2022, vol. 14, issue 14, 1-16

Abstract: For underground water reservoirs in coal mines, the complex water-rich environment and changing overburden stress can damage coal pillar dams. In this paper, the coal samples from coal seam 2 2 of Shangwan coal mine were taken as research objects and the damage mechanism and characteristics of coal samples with different moisture content and wetting-drying cycles under cyclic loading were investigated. The results show that as the moisture content and wetting-drying cycles increase, the post-peak stage of the coal samples under cyclic stress becomes obvious, and the hysteresis loop changes from dense to sparse. Compared to the uniaxial compression experiment, when w = 5.28% (the critical water content), mechanical parameters such as peak strength and modulus of elasticity decrease the most. Under cyclic loading, the damage mode of both sets of coal samples was tensile damage, but the increase in wetting-drying cycles promotes the development of shear fractures. For evaluating fracture types, the RA-AF density map is more applicable to wetting-drying cycle coal samples, whereas for the coal samples with different moisture contents this should be carried out with caution. This study can provide some theoretical basis for the stability evaluation of coal pillar dams in underground water reservoirs.

Keywords: moisture content; dry–wet cycles; cyclic loading; injury mechanism; acoustic emission RA-AF (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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