Seepage regime in the foundation of the Sayano-Shushenskoe dam during construction and operation

Conclusions

• 1. A tendency toward an increase of seepage discharges was observed in the dam foundation and bank abutments up to 1996, having reached 549 liters/sec in 1996 versus 240 liter/sec in 1990 and 190 liters/sec expected according to the design. This indicated the development of decompression of the foundation and grout curtain.

• 2. After repair works with the use of cement grouts at low upper pool levels, positive changes in the seepage regime did not occur: the hydraulic connection between holes along cracks both with and across the flow remains intact; the tendency toward an increase of discharges and heads behind the grout curtain remains.

• 3. When designating the technology of carrying out the grouting works and materials for subsequent repair operations, it is necessary to take into account the characteristics of the seepage state of the foundation: the amount of opening of the cracks in the foundation, the high seepage velocities, the active reaction to any external actions on the structure, the communication and hydraulic connection between local stretches of the foundation.