Abstract:In order to explore the enhancement effect of hybrid fiber content on the mechanical properties of cemented tailings backfill, three kinds of fiber materials were selected for slump, uniaxial compression and SHPB impact tests. The test results show that the fiber material has a great influence on the fluidity of the filling body. The higher the fiber content is, the weaker the fluidity is, and the polypropylene fiber has the most significant influence on the fluidity. The improvement of dynamic and static mechanical properties of filling body by hybrid fiber is affected by the content of hybrid fiber. In a certain range, with the increase of fiber content, it shows a trend of increasing first and then decreasing. The 0.4 % mass fraction of polypropylene fiber has the most significant increase in the early compressive strength of filling body. At the standard curing age of 28 days, the improvement of dynamic and static mechanical properties of filling body by steel fiber is greater than that of the other two fibers. The hybrid fiber with a total fiber content of 1.4 % ~ 1.5 % has the largest increase in the dynamic compressive strength of the filling body, and the increase is greater than that of higher or lower fiber content. At the same average strain rate, with the increase of hybrid fiber content, the reflection energy and absorption energy of the filling body decrease first and then increase, and the transmission energy increases first and then decreases. The test results show that the appropriate amount of hybrid fiber can effectively improve the mechanical properties of the filling body, which is conducive to the safety of filling mining, and has a certain guiding role in the design of mine filling body materials.

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