纤维加筋红黏土的抗拉特性研究

Tensile Properties of Polypropylene Fiber Reinforced Red Clay

为深入探究纤维加筋红黏土中纤维与土体间相互作用对土体抗拉特性的影响规律及其机理。以桂林红黏土为研究对象,利用搭建的土体抗拉强度测试装置以及数码显微镜,开展了最大干密度和最优含水率下不同聚丙烯纤维掺量的拉伸试验。结果表明,聚丙烯纤维掺量能大幅提升红黏土抗拉强度和拉应变;随着聚丙烯纤维掺量增加,抗拉强度明显增大,红黏土破坏类型从纯素土的脆性破坏转变为塑性破坏。相较于纯素土而言,聚丙烯纤维掺量使土体破坏时出现明显的拐点;红黏土的极限拉应变随掺量增加而大幅提升。分析表明,纤维加筋红黏土的抗拉力学行为主要归因于土颗粒和纤维间产生的机械咬合力,两者相互摩擦抵抗断裂;此外,因纤维和纤维之间相互交错形成纤维网络,土体受到三维多向拉筋作用从而提高抗拉强度。

In order to further study the interaction mechanism between the fiber and the soil in the fiber reinforced red clay samples and to improve the tensile strength of the soil,this paper presents an investigation result of Guilin red clay using the soil tensile strength testing device and microscope,the tensile tests of different polypropylene fiber content under the maximum dry density and optimal moisture contents.The microscopic mechanism was observed.The experimental results show that the content of the polypropylene fiber can greatly improve the tensile strength and the strain of the red clay,and make red clay sustain a greater tensile deformation.With the increase of the polypropylene fiber content,the tensile strength increases obviously,and the failure type of the red clay changes from the brittle failure mode to the plastic failure mode.Compared with the plain soil samples,the polypropylene fiber content makes the soil appear obvious inflection point when it is failed under the loading.The ultimate tensile strain of the red clay samples increases by 329.9%with the increase of the fiber content.After analysis,the tensile behavior of the fiber improved red clay samples is mainly attributed to the mechanical adhesion force between the soil particles and fibers,which friction each other to resist the fracture.As well as the fiber and fiber interweave to form a fiber network,which is acted by the threedimensional multidirectional tendons to improve the tensile strength of soil samples.