Steel Fibre-Reinforced Shotcrete as an alternative to conventional concrete tunnel lining: a case study of Gulpur Hydropower Project

Abstract

ABSTRACT For the first time in Pakistan, Steel Fibre-Reinforced Shotcrete (SFRS) is used as the final lining for the Diversion Tunnels of Gulpur Hydropower Project. The project’s diversion tunnels were opened for operation since 2016 and along with the normal operating inflow of the river, over the course of 3 years, have experienced two major floods as well. Due to schedule constraints, conventional-reinforced concrete lining was only used in the invert portion and the side walls up to a height of 1.6 m in both tunnels and for the remaining portion of the tunnels, SFRS was used. The major advantage of SFRS over conventional lining is the reduced construction time compared to when conventional lining is used. Quantity and cost comparisons of both lining methods show that SFRS is almost 25% more costly per meter length of tunnel while more than 40% faster to construct compared to conventional lining. As-built sections show very little reduction in the area of lining which exemplifies SFRS as not only stable but flood resistant as well.