CLIENT: EEPCO (Ethiopian Electric Power Company)
The Gilgel Gibe II Power Station is a hydroelectric power station located on the Omo River, Ethiopia, in the East African Rift Valley. The excavation of the 26km TBM-excavated headrace tunnel experienced very challenging ground conditions throughout the construction (2005-2010), with completion delayed when the intake portal TBM came to a halt on encountering exceptionally adverse ground conditions.
Following the halting of the TBM, in 2008 Geo-Design undertook an independent assessment of ground conditions and collapse mechanisms for a section of the TBM tunnel, which was located under very high cover and with flowing ground conditions associated with a large fault structure.
Failure inside TBM tunnel – Gilgel Gibe, Ethiopia