ABSTRACT
Experience in underground construction practice to date has indicated that creep deformations in conventionally-reinforced shotcrete and Steel Fibre Reinforced Shotcrete (SFRS) are small once hardening beyond the initial few weeks of hydration has occurred. This is apparent in both the cracked and uncracked states. At the same time, shotcrete reinforced with macro-synthetic fibres has become well established as a means of ground support in mines. This type of FRS has demonstrated an ability to deform with highly plastic ground and thereby control stability. However, considerable debate has arisen within the underground design community about the merits of using shotcrete reinforced with macro-synthetic fibres in civil tunnel linings. The most common argument made against the use of macro-synthetic fibres in this application has been concern about the magnitude of creep-related deflections likely to occur in the long-term under gravity loading. The present investigation was instigated to determine the magnitude of time-dependent post-crack deflections typical of shotcrete reinforced with macro-synthetic fibres and to compare this with steel FRS tested under nominally identical conditions.
