Passage of ice during construction of the Sayano-Shushenskoe hydroelectric station

Conclusion

During construction of the Sayano-Shushenskoe hydrostation ice was passed through the narrowed 130-m wide channel for 7 years and for 3 years through the 5.3-m wide dewatering outlets which, during the ice run, were not submerged and operated as narrow deep bays with wide separating piers. Observations established that the planned and actual outer and height contours of the earth cofferdams and cribs of the foundation area of the first stage and their construction successfully performed their functions under rather complex ice conditions (especially in the springs of 1969–1971).

For the first time in hydrotechnical construction practice conparatively large ice runs were passed through 5.3-m ice-discharge bays. The appropriate hydraulic conditions (flow depth more than 9–10 m and approach velocities more than 3 m/sec) were the decisive factors providing for the successful passage of ice under these conditions.

Consideration of the experience by previously constructed Siberian hydrostations on rivers with heavy ice runs made it possible to make simple and economic decisions with respect to individual problems (rejection of high jackets on the cribs, use of earth cofferdams, use of narrow first stage dewatering outlets). In the future when using schemes for ice passages through narrow dewatering outlets under more rigorous climatic conditions it is necessary to take into account the possibility of their considerable freezing over and intensified ice formation in them during the winter.

The solution to complex problems of ice passage when constructing hydrostations on the middle and lower reaches of large Siberian rivers requires further on-site observations at hydrostations under construction and improvement of model-calculation methods of investigation.