聚丙烯纤维网湿喷混凝土隧道衬砌的应用研究

针对传统喷射混凝土用于隧道衬砌存在的质量离散性大、抗拉强度低、密实性和耐久性差等问题,研究采用在混凝土中掺入聚丙烯纤维网的解决方案。通过对不同掺量的聚丙烯纤维网混凝土试件进行实验分析,结果表明,在混凝土中掺入体积掺量为0.1%~0.2%的聚丙烯纤维网,可使抗拉强度提高50%以上,抗渗性能提高55.6%以上。在宝兰铁路东巨寺沟隧道直接喷射聚丙烯纤维网混凝土,并对喷层厚度测量和外观质量观察表明,喷层厚度均匀,表面平整;3个分段试件的强度值离散性小,平均抗压强度分别为43.2,44.3,44.2MPa,平均抗折强度分别为5.7,5.9,5.9 MPa。聚丙烯纤维网混凝土既可用于隧道开挖后的支护,又能用于隧道的永久衬砌。

Application Research on Tunnel Lining of Polypropylene Net Fiber Shotcrete

There are some defects in common shotcrete, such as large discreteness, low tensile strength and density, and poor durability. In order to improve the performance of the shotcrete, a reinforcing material-polypropylene net fiber is used in shotcrete. The mechanical characteristics of polypropylene net fiber concrete with different mix ratio are discussed in this paper. Results show that the best mix ratio of polypropylene net fiber is between 0. 1% and 0. 2 %, and the tensile strength and anti-seepage of shotcrete with polypropylene net fiber is about 50% and 55.6% higher than that of shotcrete without polypropylene net fiber. The polypropylene net fiber shotcrete has been used in Dongjusigou tunnel of Baoji-Lanzhou railway line, the thickness and roughness of shotcrete is satisfying. The strength values of three sections are of little discreteness. The average compression strength in different section is 43.2, 44.3 and 44.2 MPa respectively; the flexural strength is 5.7, 5.9 and 5.9 MPa correspondingly. It is indicated that the polypropylene net fiber shotcrete can be used as secondary lining of tunnel as well as primary support.