Engineering Services for Remedial Structures on The Spillway of Keban Dam – Turkey

Project Name: ENGINEERING SERVICES FOR REMEDIAL STRUCTURES ON THE SPILLWAY OF KEBAN DAM

Country: TURKEY

Finance Source: LÄ°MAK Construction Company

Tags: Turkey, Local, HEPP, Design

Narrative Description of Project:
Keban Dam is the first major project of the large dams system (Keban Dam, Karakaya Dam, Atatürk Dam, Birecik Dam and Karkamış Dam; from upstream to downstream) on the Euphrates River of Turkey. Dam body is a combination of rockfill and concrete gravity structure with a height of 207 m above foundation, a crest length of 1125 m, embankment volume of 15.5×106 m3 and concrete volume of 1.24×106 m3. Reservoir volume and area are 30.6×109 m3. and 675 km2 respectively.

The main purpose of the dam is the production of 5800 GWh hydroelectric energy annually through the powerplant with 8 units, each with an installed capacity of 167.5 MW.

Spillway located on the concrete gravity structure is designed for a capacity of 17000 m3 /sec and equipped with six radial gates of 16 m width and 15 m height. Discharge channel is 470 m long, 119 m wide and divided into 3 bays with partition walls and it ends with a groove-type flip bucket before discharging freely into the tailwater.

In the course of operation since 1974, important cavitation damage has been occurred along the bottom of discharge channel and also progressive scouring at the downstream of flip bucket.

Description of Actual Services Provided by TEMELSU:
Final design and detailed design of spillway remedial structures against cavitation and scouring problems including the preparation of technical specifications and bid documents were completed by Temelsu until October 1991. To prevent cavitation, 4 groove-type aeration channel and air shafts have been designed and constructed along the discharge channel using special techniques for demolition of the existence concrete. Also a separate drainage system for the water filled in the aeration grooves has been designed. As a permanent solution to scouring, one row of bored piles with 2 m diameter were drilled at downstream of flip bucket to allow dewatering during construction and to protect the massive concrete blanket which was placed just downstream of the flip bucket with a crest profile that suits the water jet to minimize its impact effect.