Bibliothek

Notizen: Conclusions 1. The corrosion rates of steel in water during short-term tests under conditions prevailing at the Krasnoyarsk hydroelectric plant, and also in all river basins of the middle latitudes in the northern hemisphere vary considerably during the course of the year. They diminish markedly in the winter, reaching 10–20% of the corrosion rates in seawater, and increase vigorously in the summer, attaining 300% of the corrosion rates in that same medium. 2. In the Enisei, as in the other rivers, the corrosion rate of steel in the zone of periodic wetting under the surface of the water is, in contrast to marine conditions, close to the corrisoon rate in the air, while under marine conditions, vigorous corrosion is observed to be many times greater in this zone. 3. Under Enisei River conditions, as in other rivers, the underwater zone is the most aggressive; this also distinguishes river from marine corrosion, where the rate in this zone is 4–5 times lower than that in the zone of periodic wetting, and is approximately equal to the rate in the air. 4. Long-term field studies conducted at the Krasnoyarsk hydroelectric plant indicate that under conditions prevailing here, the application of coatings to mechanical equipment and metal structures would probably be necessary not so much to protect them from corrosion, as to provide the required ornamental appearance. 5. Metallizing the surface of design components with aluminum to a thickness of not more than 50 μm can be recommended as a protective-decorative coating. Use of cathodic protection is expedient for the underwater zone, where the corrosion rate (possibly due to the formation of vapors of differential aeration and the combined action of corrosion and erosion) may have a more significant effect on the designs than has been shown by the testing of specimens.

Notizen: Conclusions 1. In order to increase the efficiency and provide for a modern level of operation of such large-scale structures as the Krasnoyarsk hydroelectric plant, it is necessary during design to develop a special section in the plans which is devoted to problems associated with the organization of the operation of hydraulic structures and their inspection with consideration given to requirements set forth in the scientific organization of labor. The following should be included with the basic problems that require solution in this section of the plan: development of a scheme for the preventive-repair maintenance and conveyer servicing of hydraulic structures; development of means and systems for remote monitoring and signaling; development of centralized-control systems for hydraulic structures with provision for a maximum of facilities with which to conduct observations; automatic processing of the results of observations with development of a special subsystem for monitoring hydraulic structures in the automatic control portion of the power system; development of an inspection program with consideration given to a reduction in the number of points and in the frequency of measurements, as well as of visual observations during the course of time. 2. An important factor in upgrading the quality of inspection of hydraulic structures may be the development of the most generalized criteria of their reliable operation with a reduction in the volume of observations at individual points in the structures. These criteria should be developed for large hydroelectric plants with the participation of scientific-research organizations. 3. For large hydroelectric plants it is expedient to supplement the composition of inspection with a system of ultrasonic sensors inserted near the surfaces of the structures in the frost-resistant zone to monitor variation in the properties of the concrete during operation. 4. Before turning a hydraulic facility over to the State Commission, it is necessary to inspect and test, as a completed complex, the measuring systems installed to monitor the condition of the hydraulic structures.

Notizen: Conclusions 1. In the early stages of construction the management of the Krasnoyarsk hydroelectric plant was included, together with design and construction organizations, in work on improving design solutions to increase the operating quality of the structures and equipment. 2. Participation of management in the analysis of design solutions has made it possible to discover and resolve in good time a number of problems associated with the provision of effective operational organization: selection of intake elevations for the hydraulic turbines, setting of the machine gallery, layout of the open distribution device, selection of transport systems, the disposition and outfitting of workshops, etc. 3. Operating personnel, together with plant fabricators, have completed a large volume of work involving the mastering of heavy-duty unique equipment and the improvement of its reliability. 4. The experience gained at the Krasnoyarsk plant should be distributed for use in all hydroelectric plants under construction, while the noted disadvantages should be considered in designing large-scale hydroelectric plants.

Notizen: Conclusions 1. The positive results of grouting cracks in concrete of the upstream face of the Sayano-Shushenskoe dam are not limited to suppression of seepage between elevations 344 and 359 m. Substantial compression of concrete of the first column and beyond the limits of this zone at higher and lower elevations was obtained without advance of the cracks into the depths of the dam during injection of the grout under high pressures, which also prevented seepage. 2. It is necessary to consider well-founded the requirement of limiting additional opening of cracks during grouting to 1.5 mm. 3. When making calculations for estimating the effect of grouting on the SSS of the dam, one should not proceed from the average pressure in the crack being grouted, since its value is difficult to establish. It can tentatively be considered a rigid inserts over the entire front of the crack with a thickness on the upstream face of 1.75–2 mm and converging to 0 in the zone of joint I–II.

Notizen: Conclusions 1. In designing heavy-duty high-head hydraulic facilities, where significant hydrodynamic effects on elements of the hydraulic facility should be expected during operation of dummy spillways and units, it is necessary to perform their dynamic calculation. 2. The MARCHI-designed superstructure of the machine gallery at the Sayano-Shushenskoe hydroelectric power plant is subject to rather vigorous vibrations due, in particular, to the operation of the dam's spillways. Nontraditional structural solutions with respect to the installation of dynamic dampers, which may be adopted after appropriate computational and field investigations, are required for this structure to lower the swings of the oscillations. 3. Development of maximum oscillations in strictly defined areas occurs not as a result of different stiffnesses of the components of the superstructure of the machine gallery at the Sayano-Shushenskoe hydroelectric plant or the stiffness of the reinforced-concrete unit blocks, but most likely due to the mutual effect of various elements of the hydraulic facility as sources of wave oscillations that develop due to the effect of hydrodynamic forces during idle discharges on the toe basin.

Notizen: Conclusions 1. The design organization could not have contemplated the scale of the loosening of the rock mass, as a result of which the lower surface of the dam and the contact zone of the foundation bed were not instrumented to the degree necessary for direct measurments of openings and loosening in the contact zone. 2. The readings of available slit gages are insufficient for estimation of total openings. 3. Lower and upper estimates of the openings in the contact zone near the thrust face are obtained from readings of transverse hydrolevels. It is understood from geometric representations that even for several horizons, the total opening cannot exceed the vertical component of the displacements obtained as a result of inclination of the lower surface. 4. In addition to estimates of maximum expected openings, the fact of the “in-leakage” of these values from year to year is of interest. Estimating this process for the period from 1991 through 1997 from hydrolevel readings, we obtain an additional opening of from 2.3 to 4.4 mm in section 33 (according to minimum and maximum estimates). This process proceeds more vigorously under the spillway portion of the dam than beneath the powerhouse portion, and it is especially noticeable beneath section 45.