The design of steel-lined pressure tunnels and shafts

摘要

The state-of-the-art of the design criteria and the methods for load sharing calculations for steel linedrnpressure tunnels and shafts is reviewed here. The design methods mainly based on allowable stresses in the steel liner can be questioned if high strength steel is used. After addressing the problematic nature of such steel, the author outlines the application of fracture mechanics theory in the design of steel liners. A new research project is briefly described, where the acoustic signal of waterhammer will be used to access the structural stiffness of steel lined pressure tunnels and shafts.rnSteel-lined pressure shafts and tunnels in rock are the key structures of hydroelectric powerplants. Because of the higher peak energy demands, hydro plants have to operate under rough conditions as regards the output power with improved efficiency, flexibility and safety. Therefore, the development of new design guidelines for pressurized waterway systems is required, based on the detailed stress-strain behaviour of the lining, and taking into account a combination of different materials such as high strength steel, concrete and rock. The importance of such new guidelines has been underlined by the collapse of the shallow pressure shaft at the Cleuson-Dixence hydro plant in Switzerland, in December 2000.