engleski

Optimized composition of UHPC for tunnel lining

Following stabilization of tunnel excavation, one of the possible methods for constructing secondary tunnel lining is the use of precast tunnel segments. Design, manufacture and installation of precast tunnel segments depend on the kind, cross-section and length of the tunnel, the geological and hydrological conditions of the soil, and the method of excavation. Conventionally reinforced precast tunnel segments use a high percentage of reinforcement which increses the cost of their manufacture and instalation. Therefore, a large percentage of the reinforcement should be eliminated by using fibre reinforced concrete instead. Over the last few years, several tunnels have been constructed worldwide with precast reinforced concrete tunnel segnents. However, most of these tunnels have smaller cross-sections and are not exposed to heavy road and railway traffic. Recent research has moreover shown that precast tunnel segments manufactured with plain fiber-reinforced concrete have a lower bearing capacity than conventionally reinforced concrete segments. By increasing the amount of admixed fibers, and by modifying the cement matrix, high-performance fiber-reinforced concretes are obtained. This paper analyses the influence of the types and quantities of steel fibers, the maximim aggregate grain sizes and the curing methods on mechanical properties of high-performance fibre-reinforced concrete.

secondary tunnel lining; precast segments; high performance concrete; fiber reinforced concrete

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