单根聚丙烯纤维在植被混凝土中的拉拔特性及临界长度研究

Single Polypropylene Fiber Determine Critical Fiber Reinforcement Length and Analysis of Pullout Characteristics for Fiber Reinforced Soil Vegetation-growing Concrete

纤维加筋技术在复合土和混凝土等工程加固领域应用广泛,但在生态护坡领域的应用则鲜有报道。通过自主设计的试验装置,研究了单根聚丙烯纤维在不同含水率、不同干密度和不同龄期植被混凝土中的拉拔特性,分析了拉拔试验前后纤维的显微特征,并确定了临界加筋长度经验公式。研究表明:纤维拉力-位移曲线呈显著的多峰特征,主要与植被混凝土中存在水泥水化产物有关;1 d试样界面抗剪强度在最优含水率时存在极小值,主要原因是试样初期的筋-土界面锚固力提高值相较于摩擦力减小值要低;随着干密度和龄期的增长,界面抗剪强度和残余抗剪强度都显著提高。通过多元线性回归分析,得出植被混凝土中纤维临界加筋长度的经验公式,对提升植被混凝土在高寒、强降雨、坡面高陡等恶劣环境下的工程耐久性有一定指导意义。

Fiber reinforcement technology is widely used in the field of composite soil and concrete reinforcement,but it is rarely reported in the application of ecological slope protection.Through the test device is designed,on the drawing property of single polypropylene fiber in different moisture content,dry density and different vegetation-growing concrete at different ages in the analysis of the microscopic characteristics of fiber pull-out test,and the empirical formula to determine the critical reinforcement length.Research shows that the displacement curve of fiber tension is multi peak characteristics,and the main vegetation in concrete cement hydration products;strength has a minimum value in the optimal water content of 1 d samples of interface shear,the main reason is the initial sample of reinforced soil interface anchoring force increase compared to the value of friction is reduced to low values;with the dry density and the growth of the age,the interfacial shear strength and residual shear strength are significantly increased.Through multivariate linear regression analysis,the empirical formula of critical reinforcement length in vegetation-growing concrete is obtained,which is of guiding significance for improving the durability of vegetation-growing concrete in harsh environment such as high cold,heavy rainfall,high and steep slope.