Seepage regime in the foundation of the Sayano-Shushenskoe hydroelectric station dam during staged filling of the reservoir

Conclusions

• 1. The means of engineering protection of the foundation of the structure from seepage specified by the design of the dam of the S-Sh HES provided an effective reduction of the head on the upstream stretch of the underground contour. In this case, the value of the uplift on the base of the dam does not exceed the design values, and the discharges in the drainage devices remain below the values specified by calculation.

• 2. The seepage inhomogeneity of the dam foundation is comparatively large and has an ordered character, which was not taken into account in the seepage calculations. Modeling of such an object requires the fabrication of three-dimensional models.

• 3. During staged filling of the reservoir, noticeably abrupt changes in the permeability of the permeable medium occurred along with slowly developing processes of an increase of fracture porosity corresponding to a general increase of the head on the structure. Such sharp changes occurred during filling of the reservoir at a rate greater than 2 m/day.

• 4. A tendency toward a decrease of the effectiveness of the curtain and drainage device is noted with the course of time. The causes of this, as is seen, are decompression of the contact zone related to seasonal variations of the stress-strain state of the medium in the region of transition of the dam with the foundation rocks and intense deposition of sediments in the drain wells.