聚丙烯纤维加筋铁尾矿砂的宏/微观结构特性分析

为研究聚丙烯纤维对聚丙烯纤维加筋铁尾矿砂的抗剪性能、抗压性能和宏/微观结构特性的影响，使用抗剪强度确定其抗剪性能，用无侧限抗压强度确定其抗压性能，并采用宏观破坏和扫描电子显微镜（SEM）微观分析相结合的方法，评价纤维加筋尾矿砂的结构变化。试验研究了纤维掺量和含水率对尾矿砂试件的影响，结果表明：纤维是影响试件抗剪强度和单轴抗压强度的重要因素，且增强效果主要取决于筋/砂之间界面的摩擦和黏结。直剪和无侧限抗压强度试验最佳的纤维含量是0.3%，最佳的含水率为12%。此外，宏观结构破坏分析和SEM微结构试验表明：聚丙烯纤维的作用主要是桥接裂纹，通过筋/砂界面的摩擦和黏结抵消外力，以达到提高强度的目的。

Macrostructural and Microstructural Properties Analysis for The Polypropylene Fiber-reinforced Iron Tailings Sand

Experimental study was carried out to investigate the influence of polypropylene fibre on the shear behavior， compressive behavior and microstructural properties of polypropylene fiber-reinforced iron tailings. The shear behavior was determined by the shear resistance， and the compressive behavior was determined by the unconfined compressive strength. The structural changes of the fiber-reinforced tailing sand were evaluated by macrostructural failure analysis and microstructural test with SEM analysis. The tests was designed to research the influenence of fiber contents and moisture contents on the tailings specimens. The results showed that the fiber is an important factor to improve the shear strength and unconfined compressive strength， and the reinforcement effect mainly depends on the friction and bonding between the fiber interface and the sand interface. The best fiber contents is 0.3%， and the best moisture content is 12% in the shear tests and unconfined test. In addition， the macroscopic structural failure analysis and SEM microstructural tests showed that the action of polypropylene fiber is mainly to bridge the crack and counteract the external force through the friction force at the fiber interface and the sand interface to achieve the purpose of increasing the strength.