A design is proposed for a stepped spillway.A detailed design of the Boguchany HPP with a rated capacity of 3000 MW (nine generating sets each with a capacity of 330,000 kW and a reservoir at elevation 208 m was approved in 1979 by order of the Council of Ministers of the USSR in an agreement reached with the State Committee on Construction. In 1982, the first cubic meter of concrete was placed in the basic structures of the hydroproject. From 1993 through 2005, construction proceeded at extremely low rates on structures of the hydroproject. After the decision was made to resume construction on the BoHPP in 2006, the institute Gidroproekt (Moscow) was commissioned to render a partial adjustment to technical solutions of the 1979 design. Basic premises for partial revision of the technical solutions were:-a change in basic positions of the regulatory base for the design of water-development works;-a deficiency of carrying capacity of the spillway structures at the hydroproject in periods of permanent and temporary service; and, -the need to ensure operational reliability of the spillway structures, and the possibility of performing their running repairs.Agricultural and water-power analyses performed in compliance with requirements of the Construction Rules and Regulations indicated that the carrying capacity of the hydroproject in the periods of temporary and permanent service is lower than that required for passage of the spring flood and high water of the summer and fall. To retain the design values for the maximum water level in the upper pool, and ensure reliable passage of flows into the lower pool, it was necessary to increase the carrying capacity of the hydroproject by installing a second spillway (No. 2) in addition to the existing and partially constructed No. 1 spillway.In the design, the No. 2 spillway is to be placed in the segment containing the unfinished No. 20 -22 sections of the concrete dam alongside the partially constructed No. 1 spillway using the pit opened for resumed construction of generating sets No. 10 -12 of the powerhouse (a decision to cancel construction of these sets was made after the pit had been opened). Three alternate construction schemes of the No. 2, spillway, which are distinguished one from the other primarily by the method used to dissipate the energy of the discharge flow, are called for in the design. In two of the alternate schemes, it is specified that the energy of the flow be dissipated in a tow basin, and a scheme whereby the flow is discharged into the lower pool beyond the limits of the structures being erected is called for in the third.In hydrotechnical construction, problems associated with effective dissipation of excess flow energy, and erosion control of the surface of the water-passing structures determine their design for the most part. Preliminary analysis indicated that the installation of a stepped overflow face for the No. 2 spillway will ensure: -operation of the spillway in a cavitation-free regime by reducing the velocities of the flow, and its vi...

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Results of seismic observations of the dam indicated that its resonance vibrations do not correspond to the basic operating frequency of the generating sets.According to a seismic-zoning map [21], the area surrounding the Sayano-Shushenskaya hydroproject falls within zones of 7 -10-point tremors. Considering seismological research [15,22], the location of the dam is classed as an 8-point intensity zone.The reservoir behind the Sayano-Shushenskaya Hydroelectric plant (SSHPP) is situated in a region where two large-scale structures of the folded Altay-Sayan region merge: the deeply folded West-Sayan uplift and the Tuva inter-mountain depression. The geology of the region where the SSHPP resides is characterized by the existence of a very broad range of structures: from regional structures with an expanse in the hundreds of kilometers to higher-order structures measured in several kilometers. The dam behind the SSHPP is located at the center of the long, narrow (30 -40 km) anticlinorium Dzhbashskii block of recent proterozoids, which is framed by early paleozoids. The complexes of these deposits are broken-through by middle Paleozoic granitoids and gabbroids. The northern boundary of the block passes along the North-Sayan regional fold, and the southern boundary along the Borusskaya fault. The boundary of the mountainous structure of the Western Sayan and the Minusinsk trench passes along the deep Minusinsk fault 35 -40 km north of the dam. The Kantegirka regional fault passes 30 km to the south of the dam. Of the enumerated faults, only the Borusskaya lies within 15 km to the south of the dam, and part of ist subparallel northern branch shows a clearly expressed face of the latest activation. A decipherable virgin seam of the fault can be distinctly traced over a distance of 40 km [22]. According to results of geologic-geophysical investigations, a complex system of faults that are branching outward from the regional faults are also observed below the body of the Sayano-Shushenskaya Dam.Seismological observations of the area are divided into two periods: pre-instrument, and instrument. The first includes archival information [8,17]. The second can be subdivided into the following three stages:-first, predesign -determination of the "stated" intensity of tremors in the area of the hydroproject, which has been made by field detachments of the Institute of Physics of the Earth;-second -continuous regime seismological observations in the Altay-Sayan region, which were begun in 1962 by the Siberian Division of the Russian Academy of Sciences, and the surrounding area of the modern proving ground at the SSHPP; and, -third -local observations in the region of the Sayano-Shushenskaya hydroproject, which were begun in 1990 in conformity with design documentation for construction of the SSHPP on the initiative and support of V. I. Bryzgalov the General Director of the SSHPP at that time.The decision to create a proving ground for geodynamic observations in the area of the Sayano-Shushenskaya hydroproject was made by the RAO ...

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