RESEARCH AND APPLICATION OF PVA CHOPPED FIBER SHOTCRETE

Shotcrete has the advantages of short setting time, high bond strength and good supporting effect. However, there are many disadvantages in the engineering application of shotcrete, such as high rebound ratio and unqualified sprayed quality. This paper took the initial supporting shotcrete of Chongqing Hongyan Village tunnel project as the engineering background. The experimental and numerical simulation methods were used to study the optimum content of fiber in PVA chopped fiber shotcrete and its influence on the shotcrete rebound ratio, the stability of tunnel cavity and the deformation of surrounding rock. The results showed that a certain amount of PVA chopped fibers could reduce the rebound ratio of shotcrete, and the optimum amount of fiber was about 0.132%. Compared with ordinary shotcrete, the PVA chopped fiber shotcrete could reduce the vertical and horizontal displacements when the cavity was unstable, and the maximum reduction could reach 2.0% and 4.3%. The maximum stress of the fiber shotcrete layer could be increased by 14.3% compared with that of ordinary shotcrete.