Structural Design of Wells Hydrocombine

A new design concept for a hydroelectric project has been developed, combining powerhouse, spillway, fish facilities, and switchyard into a single structure called Hydrocombine. Hydrocombine superstructures or unit pits were designed as reinforced arch-buttress rigid frames. These structures withstand reservoir, spillway gates and stop-log loadings. Unsymmetrical loading, including unsymmetrical hydrostatic loading during spillway operation, produces eccentricities of thrusts much larger than encountered in ordinary arch dams. The adopted procedure, working stresses and reinforcing, produce very watertight structures. Location of draft tube gates in a continuous gallery requires penetrations through the critical wall diaphragms in the Hydrocombine. The severe stress conditions created by this gallery are obtained by reducing the complicated structure to a simplified frame referred to as a toe-frame. The validity of this design approach is verified by the photoelastic model study.