聚丙烯纤维和粗骨料对尾砂胶结充填体延性和流动性的影响

Effect of polypropylene fiber and coarse aggregate on the ductility and fluidity of cemented tailings backfill

添加聚丙烯纤维和粗集料已成为提高尾砂胶结充填体强度和稳定性的常用方法,研究尾矿-骨料比和纤维含量对CTB试样力学性能的影响具有重要意义。本文基于抗压强度、坍落度和微观结构试验,建立了纤维和尾骨比对CTB试样强度、延性和流动性影响的回归模型。结果表明:考虑抗压强度、开裂应变、峰值应变和峰后延性,尾矿-骨料比为5:5、纤维掺量为0.5 kg/m^(3)时性能最优;其中尾骨比与强度呈一元二次关系,与坍落度呈负线性相关。微观结构分析结果表明,纤维主要表现为桥接作用,棒磨砂作为充填体骨架,可提高CTB的致密性和峰后延性。本文研究结果对认识和应用粗集料和纤维来改善CTB的力学性能具有重要意义。

Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.