State of the Sayano-Shushenskoe dam during fourfold rise of the upper pool level to the elevation of the normal pool level

Abstract

1. An analysis of the data of on-site observations in 1990–1993 showed that after a fourfold rise of the water level in the reservoir of the Sayano-Shushenskoe dam, a tendency toward stabilization of most monitored parameters characterizing the static behavior of the structure was noted. 2. The increase of the irreversible component of radial displacements, tilts, and stresses in concrete slowed. The opening at the rock-concrete contact during seasonal rises of the upper pool level is gradually stabilizing, and the depth of opening (from the upstream face) is not increasing. Although the seepage discharges through the foundation during the last four years increased, the rate of increase decreased by the end of the indicated period. 3. An increase of drainage discharges and a change in the piezometric heads (sometime anomalous) with the same upper pool levels indicate continuing changes in the stress state in the dam foundation, which is causing the formation of cracks in the rock mass. 4. The magnitude and character of the change in stresses in the arch abutments and strains in the rock mass of the bank abutments indicate that the actual yielding of the banks was greater than was assumed in the design. 5. Opening of horizontal joints and cracks on the upstream face within the 50-m zone from the contact during seasonal rises of the UPL to the NPL is continuing. Here a tendency toward penetration of the opening into the depths of the concrete mass is observed. The character of variation of the cantilever stresses at the upstream face in recent years indicates opening of horizontal joints and cracks at elevations higher than 50 m from the base of the structure.