ABSTRACT
The paper describes the main aspects of the design of the Power-waterways of Gibe III Hpp (Ethiopia). The plant includes a 250 m high RCC gravity dam, two 11 m diameter and 1,2 km long power waterways excavated in the left bank of the river. The project commenced in 2006, the dam was impounded in 2015. At present the plant is completed and in operation. The maximum reservoir level reached at date is 215 m over the foundation (90% of maximum head). The design was challenging in reason of the huge size of the works, to their complexity and considering that these power waterways operate with heads up to 210 m of water column, with a total discharge up to 950 m3/s. The tunnel lining was one of the main topics of design, especially in relation to the control of leakage and potential risk of rock mass hydro-fracturing and hydro-jacking.
