Temporary delay of ice movement on the Yenisei river in front of the structures of the Krasnoyarsk hydroelectric power station

Conclusions

• 1. Temporary delay of ice in the upper pool, which was proposed by Lengidroproekt in order to lower the bending strength and reduce its volume before discharge through the bottom, discharge conduits, should be considered as a proven engineering measure.

• 2. When accomplishing temporary detention of ice in the upper pool there is no need for prefracturing of the ice by massive blasting.

• 3. The average velocities at the gauging station at which the ice begins to move through the structures were, for conditions at the Krasnoyarsk station, 0.55 m/sec in 1964, 0.32 m/sec in 1965, and 0.75 m/sec in 1966; here a rather close relation was observed between these values and the strength of the main mass of ice.

• 4. The period of detaining the ice flows above the structues during the spring of 1964 and 1966 was 7–8 days (relative to the date of breakup of the lower pool), and in the spring of 1965 it was 3 days. Taking into account the character of ice discharge through the bottom conduits in the spring of 1966, it can be considered that the period of temporary ice detention during this spring were the minimum permissible for the conditions of the Krasnoyarsk hydroelectric station.

• 5. The successful fulfillment of temporary delay of ice movement was accomplished as a result of timely preparation of the upstream front of the structures and the zone of presumed flooding, and also as a result of the coordinated work on gate maneuvering and well-established forecast service and ice and hydrometeorological observations.