Equivalence of mesh- and fibre-reinforced shotcrete at large deflections

Abstract

The object of the study was to determine whether extensively deflected mesh- and fibre-reinforced shotcrete as found in mines were equivalent. Full-size panel tests were accordingly carried out, from which it was concluded that uniformly distributed loading was marginally less severe than point loading, mesh reinforcement was superior to fibre reinforcement, Dramix fibre and Melt Extract fibre were similar in reinforcing characteristics, and 30–35 mm was an optimum fibre length. Consistency of fibre content could not be assured in the practical mining situation considered. A maximum content of about 1.5% could be obtained for fibre lengths not exceeding 35 mm. Owing to its greater flexibility, diamond mesh reinforced shotcrete was found to be preferable to fibre-reinforced shotcrete in excavations subject to squeezing conditions. In view of the difficulties associated with assuring the consistency of the fibre content in mining applications, it appears that the sophisticated attributes of fibre-reinforced shotcrete can only be effectively exploited in civil engineering applications in which quality assurance is subject to explicit contractual control. Key words : fibre reinforcement, shotcrete, mesh reinforcement, large deformation.