Reinforcement effect of polypropylene fiber on dynamic properties of cemented tailings backfill under SHPB impact loading

Abstract

Dynamic loads such as blasting may lead to diverse levels of failure in cemented tailings backfill (CTB) under diverse strain rates and frequency spectral amplitudes. Hence, changes in dynamic properties of filling due to these loads should be studied as a function of strain rates for CTB mixtures. In this study, the dynamic characteristics of CTB samples containing polypropylene fiber contents were examined with the use of split Hopkinson pressure bar (SHPB) system and high speed photography technology. The experimental results illustrate that the backfill has a damping influence on the elastic wave. The original waveform noise of CTB with fiber is higher than the one without fiber, and the average strain rate changes the reflected waveform. The effect is greater than the impact velocity. Secondly, the dynamic strength of CTB with fiber is higher than the static strength, which obeys a great effect of the strain rate. Meanwhile, the backfill (with fiber) stress-strain characteristics show a ‘double peak’ phenomenon, and the difference between the first and the second peak stresses decreases with increasing fiber content. The failure mode analysis demonstrated that the fiber reinforcement stopped the development of big cracks during the tensile fiber pull-out failure regime. Lastly, the findings of the present study can offer an important reference to the overall design of backfilling regarding the understanding of the good dynamic characteristics and the reduction of operational costs.