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Geomechanics and Engineering Volume 38, Number 2, July25 2024 , pages 125-137 DOI: https://doi.org/10.12989/gae.2024.38.2.125 |
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Effects of chloride ion transport characteristics and water pressure on mechanical properties of cemented coal gangue–fly ash backfill |
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Dawei Yin, Zhibin Lu, Zongxu Li, Chun Wang, Xuelong Li and Hao Hu
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| Abstract | ||
| In paste backfill mining, cemented coal gangue–fly ash backfill (CGFB) can effectively utilize coal-based solid waste, such as gangue, to control surface subsidence. However, given the pressurized water accumulation environment in goafs, CGFB is subject to coupling effects from water pressure and chloride ions. Therefore, studying the influence of pressurized water on the chlorine salt erosion of CGFB to ensure green mining safety is important. In this study, CGFB samples were soaked in a chloride salt solution at different pressures (0, 0.5, 1.5, and 3.0 MPa) to investigate the chloride ion transport characteristics, hydration products, micromorphology, pore characteristics, and mechanical properties of CGFB. Water pressure was found to promote chloride ion transfer to the CGFB interior and the material hydration reaction; enhance the internal CGFB pore structure, penetration depth, and chloride ion content; and fill the pores between the material to reduce its porosity. Furthermore, the CGFB peak uniaxial compression strain gradually decreased with increasing soaking pressure, whereas the uniaxial compressive strength first increased and then decreased. The resulting effects on the stability of the CGFB solid-phase hydration products can change the overall CGFB mechanical properties. These findings are significant for further improving the adaptability of CGFB for coal mine engineering. | ||
| Key Words | ||
| chloride ion transport; coal gangue–fly ash backfill; fracture morphology; pore analysis; water pressure | ||
| Address | ||
| Dawei Yin, Zhibin Lu, Zongxu Li and Xuelong Li: State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China Chun Wang: Henan Polytechnic University, JiaoZuo 454000, China Hao Hu: State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan 232001, China | ||