纤维增强水泥-尾砂基复合充填材料力学及流变特性研究

针对水泥-尾砂基复合充填体脆性高、强度低、质量差等问题,以聚丙烯纤维作为增强剂,探究纤维掺量和纤维长度对复合充填料浆流变行为的影响,采用Hershel-Bulkey模型(简称H-B模型)进行非线性回归拟合分析,获得充填料浆流变特性参数,借助正交设计的试验方法,考察纤维掺量、纤维长度和粉煤灰掺量对充填体养护龄期1 d、3 d、7 d和28 d抗压强度的影响。研究结果表明：随着纤维掺量的增加,充填料浆初始表观黏度和屈服应力不断增大。纤维掺量从0.2%增加至0.8%的过程中,屈服应力增加了60.19%；纤维长度从3 mm增加至12 mm的过程中,屈服应力增加了35.3%。不同养护龄期下充填体抗压强度随着纤维长度和纤维掺量的增加均表现为先上升后降低的趋势,纤维掺量0.6%和纤维长度9 mm是其临界点,适宜的纤维能在充填体内部均匀分散,形成致密的网络结构以承载外界荷载,从而改善充填体力学性能。

Study on Mechanical and Rheological Properties of Fiber-reinforced Cement-tailing and-based Composite Filling Materials

To address the problems of high brittleness, low strength and poor quality of cement-tailing sand-based composite filler, the effects of fiber dosing and fiber length on the rheological behavior of composite filler slurry were investigated by using polypropylene fibers as reinforcement, and the Hershel-Bulkey model (H-B model for short) was used for nonlinear regression fitting analysis to obtain the rheological characteristics parameters of the filler slurry, and with the help of the orthogonal design test method, the effects of fiber dosing, fiber length and fly ash dosing on the rheological behavior of the composite filler slurry were investigated. The effects of fiber admixture, fiber length and fly ash admixture on the compressive strength of the filling at 1 d, 3 d, 7 d and 28 d of curing age were investigated. The results showed that the initial apparent viscosity and yield stress of the filler slurry increased with the increase of fiber dosing. The yield stress increased by 60.19% during the increase of fiber dosing from 0.2% to 0.8%, and by 35.3% during the increase of fiber length from 3 mm to 12 mm. The compressive strength of the filler with the increase of fiber length and fiber dosing at different curing ages showed a tendency to rise first and then decrease, and the fiber dosing of 0.6% and fiber length of 9 mm were the critical points, and suitable fibers could be uniformly dispersed inside the filler to form a dense network structure to carry external loads, thus improving the mechanical properties of the filler.