Structural response and damage evaluation of Melen RCC Dam considering creep effects

Melen Dam is located on Big Melen Stream. It is about 25 km away from Düzce. Dam body is designed as a roller compacted concrete (RCC) gravity structure with 944 m crest length. The project is built to supply water to the city of Istanbul. The dam body started cracking when the dam height reached about 98 m from the foundation level in October 2016. It was initially thought that cracks were due to shrinkage resulting from the cooling of dam concrete; therefore, the construction of the dam body was not stopped but displacement measuring devices were placed on certain parts of the dam to measure movements in three directions. DSI’s (State Hydraulic Works of Turkey) remedial proposal is to construct rockfill buttressing at the downstream side of the dam to increase sliding factor of safety, to build a cutoff wall near the heel of the dam to control seepage water, and to add an upstream membrane to existing dam to prevent leakage through the dam. It is the aim of this paper to discuss the remedial proposal developed by DSI. Geotechnical parameters at the dam site are evaluated under the light of investigations, tests, and observations. Dam behavior and observed settlements are explained by relating settlements to foundation properties and geology. After studying geological and tectonic setting of the dam area together with the active faults around the region, remedial measures are evaluated by considering observed settlements upon dam body completion, by estimating settlements upon dam buttressing and impounding together with possible changes in the properties of dam foundation because of excessive settlements and saturation, and by comparing similar rockfill buttressing solutions applied to other dams around the world with the proposed one for Melen Dam.