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Rock and Soil Mechanics

Abstract

Due to the lack of effective monitoring tools for the slurry flow and strength development of high stage cemented backfill in the metal mines, the conservative design of very high strength of in-situ backfill results in excessive filling costs. The self-designed stress monitoring system were buried horizontally at four sublevels to monitor the temporal and spatial evolution three-dimensional stresses during the full sequence period (filling, curing and bearing). The results indicated that the three-dimensional stresses increased during filling and bearing period but tended to stable during the curing period. Meanwhile, the vertical stress was higher than the horizontal stress at four sublevels. During the filling period, the 51%～65% of self-weight stress was transferred into horizontal stress by the arching effect. The vertical stress and mining distance show a polynomial relationship during the bearing stage. Combined with the second step mining operation process, the mechanism of arching effect and mining-induced stress-transfer was revealed. Based on the double-arch coupling effect of stress transfer, the internal stress prediction model of high stage cemented backfill in the stope was established, which can be used to accurately determine the required strength of backfill.

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