四种人工合成纤维加筋黄土的抗剪特性

为了对比分析不同类型纤维的加筋效果及其作用机制,选取玄武岩纤维、聚丙烯纤维、聚酯纤维和玻璃纤维4种常用的人工合成纤维,以黄土为研究对象,在控制试样含水率、干密度、纤维长度和掺量等参数一定的条件下,制备5组试样进行直剪试验。试验结果表明:①纤维加筋前,土体的剪应力-剪切位移曲线存在比较明显的应变软化特征,纤维加筋后的曲线逐渐由应变软化转化为应变硬化。②纤维的掺入能够有效提高土体的抗剪强度。比较而言,玄武岩纤维的增强效果较其他纤维更好,玄武岩纤维加筋土的黏聚力和内摩擦角增幅分别为52.03%和24.30%;聚丙烯纤维次之,增幅分别为45.94%和16.01%;聚酯纤维和玻璃纤维增强效果相对较差。③加筋土黏聚力的提升与纤维-土界面的黏结力、纤维自身的抗拉强度有关,内摩擦角的提升主要与纤维-土之间的界面摩擦力有关。比较而言,玄武岩纤维的表面粗糙,抗拉强度大,使得加筋土的抗剪性能提升明显。相关分析结果可为比选纤维加筋土类型提供较好的参考。

Shear Properties of Loess Reinforced with Four Synthetic Fibers

The aim of this research is to compare and analyze the reinforcement effect and mechanism of different types of fibers. Four commonly used synthetic fibers, namely, basalt fiber, polypropylene fiber, polyester fiber, and glass fiber, were selected to prepare five groups of reinforced loess specimens for direct shear test by controlling water content, dry density, fiber length, and fiber content. Results demonstrated that: 1) before fiber reinforcement, the curves of shear stress versus shear displacement of loess displayed evident strain softening features; after fiber reinforcement, the strain softening turned into strain hardening. 2) Fibers escalated the shear strength of soil. Among the tested four fibers, basalt fiber has the best reinforcement effect by enhancing the cohesion and internal friction angle of soil by 52.03% and 24.30%, respectively, followed by polypropylene fiber with an increment by 45.94% and 16.01%, respectively. 3)The improvement of the cohesion of reinforced soil is related to the cohesive force of fiber-soil interface and the tensile strength of fiber itself; the increase of internal friction angle is mainly related to the interface friction between fiber and soil. Basalt fiber is of rough surface and large tensile strength, which significantly improves the shear properties of reinforced soil.