Performance of Foundation Ground of a Large Dam during First Filling

Dams are important engineering structures constructed to control, supply, or divert water. Seepage and high pore pressures are the most important phenomena that endanger the safety and stability of a dam. Because of the importance of primary control and evaluation of hydraulic performance of foundation ground and grout curtain of embankment dams at the beginning of operation, Alavian dam, located in the north-west of Iran, was selected as a case study and its performance was evaluated using records of pore water flux and pressures during first filling. It was found that the seepage through the foundation joints was affected by the changes of the reservoir water level although the joints were sealed by grouting. This indicates that there is an optimum length for the gallery block which minimizes the number of associated joints and the structure of the gallery doesn't tolerate critical deformations. This length depends on the engineering characteristics of the foundation ground.