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| In-situ coring quality evaluation of stope backfill in a mine in Xizang |
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Received:May 14, 2025
Revised:June 18, 2025
Accepted:June 26, 2025
Published Online:April 30, 2026
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| DOI：10.3969/j.issn.1005-7854.2026.01.001 |
| KeyWord:in-situ core sampling;backfill strength;backfill quality;microstructure;backfill process parameters |
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| 1.HTL Mining Development Co. Ltd., Lasa 851400, China;2.BGRIMM Technology Group, Beijing 100160, China;3.National Centre for International Research on Green Metal Mining, Beijing 102628, China;4.Fujian Zhenghe County Yuanxin Mining Co. Ltd., Zhenghe 353601, Fujian, China |
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| Abstract: |
| Based on the sublevel drilling and subsequent backfill mining method employed in a large copper polymetallic mine in China, this study focuses on the primary backfill body as the research subject. Through strength testing of 374 sets of specimens obtained via in-situ coring underground, the strength distribution patterns of backfill materials with cement-sand ratios of 1∶4 and 1∶6 were systematically analyzed. The results indicate that for the backfill with a cement-sand ratio of 1∶4, the strength ranges from 1.24 MPa to 6.11 MPa, with an average strength of 2.66 MPa. For the backfill with a cement-sand ratio of 1∶6, the strength ranges from 0.62 MPa to 4.94 MPa, with an average strength of 2.46 MPa. Both mix ratios exhibit significant strength variability and poor overall uniformity, reflecting imprecise control of process parameters during the preparation of the backfill slurry. Scanning electron microscopy (SEM) microanalysis reveals that the strength of the backfill primarily originates from the skeletal structure formed by needle-or rod-shaped ettringite crystals, filled with C-S-H gel. The differences in strength are related to factors such as the quantity of hydration products (ettringite and C-S-H gel), the content of unreacted water, and the porosity within the backfill. To improve backfill quality, it is recommended to increase the backfill concentration while ensuring precise and consistent dosing of cementitious materials. |
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