Experimental study of static and dynamic mechanical properties of double-deck backfill body
2017
Liu, En-yan | Zhang, Qin-li | Feng, Yan | Zhao, Jian-wen
Mined-out stope is usually backfilled several times with different backfill dosages to minimize the pressure of the backfill slurry on the stope barricade as well as the backfill cost, resulting in a double-deck or even multi-deck structure of the backfill body. The mechanical properties of a double-deck backfill body are obviously different from those of a single backfill body. The mechanical properties and failure patterns of a double-deck backfill body were studied through static compression testing using an INSTRON system and dynamic shock testing using a split Hopkinson pressure bar (SHPB). The static compression test results showed that the static compressive strength and elastic modulus values of the double-deck backfill were between those of its two corresponding single-deck backfill bodies. The SHPB experimental results indicated that compressive strength, maximum strain, elastic modulus, and volumetric energy absorbed were sensitive to the strain rate and increased with increasing strain rate at a rate between those of the two corresponding single-deck backfill bodies. Through both static and dynamic tests, it was also found that a double-deck backfill body would be damaged in a tensile type strain. As a whole, the stability of a double-deck backfill body depends primarily on the lower-strength single-deck backfill body, suggesting that more attention should be paid to the lower-strength part when backfill dosage is determined.
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