纤维加筋红黏土强度特性试验及微观机理分析

Experimental Study on the Strength Characteristics and Microstructure of Fiber-reinforced Red Clay

为研究纤维红黏土的强度特性及其筋-土作用机理,对其进行了强度特性及扫描电镜试验。试验结果表明:同一纤维掺量下,随着纤维长度的增长,纤维红黏土的黏聚力c值先增大后减小,且均高于素红黏土的;当纤维长度相同时,纤维红黏土的黏聚力c值随纤维掺量的增加表现出双峰型的变化趋势;不同纤维长度及不同掺量条件下,纤维红黏土的内摩擦角φ值无明显变化规律。基于以上试验结果,结合二元非线性回归理论,应用SPSS软件建立了纤维长度和掺量与纤维红黏土黏聚力c的二元非线性回归模型,该模型的相关系数接近1,表明该模型的准确性高、可靠性强。采用扫描电子显微镜测试手段,对纤维在红黏土中的排列模型做出假设,分析研究了不同长度、不同掺量的纤维在红黏土中的排列形态特征及纤维红黏土筋-土作用界面的微观形态特征,揭示了不同长度、不同掺量的纤维对红黏土抗剪强度指标c和φ的微观影响机理。该研究成果可为相关地区的垃圾填埋场防渗设计提供理论依据。

In order to study the strength characteristics of fiber red clay and the mechanism of stiff-soil interaction,direct shear tests were carried out in laboratory.The test results are shown as follows.Under the same fiber content,with the increase of fiber length,the c value of the cohesion of fiber red clay first increased and then decreased,which was higher than that of plain red clay.When the fiber length is the same,the c value of the cohesion of fiber red clay increases with the increase of fiber content.It shows a bimodal trend.Under the conditions of different fiber length and different content,the internal friction angle φ of fiber red clay has no obvious change law.Based on the above test results and combined with binary nonlinear regression theory,a binary nonlinear regression model of fiber length and content and c value of cohesion of fiber red clay was established by using SPSS software.The correlation coefficient of the model is close to 1,indicating the high accuracy and reliability of the model.Scanning electron microscopy was used to model the arrangement of fibers in red clay.In this paper,the arrangement and morphology characteristics of fiber with different length and content in red clay and the microscopic morphology characteristics of the interface between fiber red clay and soil were analyzed.This paper reveals the microscopic effect mechanism of fiber with different length and content on the shear strength index c and φ of red clay.This study can provide a theoretical basis for the anti-seepage design of landfill in related areas.