Library

Notes: Conclusions 1. The most substantial and sharp changes in the state of the rock-concrete contact appeared beginning in 1985 after reaching 76% of the design hydrostatic load. 2. Opening of the rock-concrete contact is distinguished by a nonuniform rate of change with time and nonuniform distribution of the amplitude of opening along the front of the dam, which reflects the complex interaction the dam with the foundation and effect of inhomogeneity of the foundation and different technological conditions of placing the contact concrete. 3. Opening of the rock-concrete contact is accompanied by substantial changes in stresses and strains in the rock and concrete of the contact zone and in the piezometric heads in the foundation, reflecting structural changes in it during interaction of the dam with the foundation. 4. In addition to the effect, which occurs for all types of concrete dams on a rock foundation, of technological factors and design differences of individual parts of the dam on the behavior of the contact zone of the foundation and concrete of the Sayano-Shushenskoe dam, also noted are such features as active opening of the rock-concrete contact over the entire length of the channel part of the foundation, presence of signs of “hanging” of the arch on the first columns on the banks, and a special stress state of the concrete in the lower part of the upstream face, which can be a reflection of the design features of the gravity-arch dam.

Notes: 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.

Notes: Conclusion Water heating of near-joint frozen concrete tested on the Sayano-Shushenskoe dam fits rather well into the technology of grouting works, does not require the installation of embedded parts, and is distinguished by simplicity and, as applied to the construction conditions of the structures, by sufficient reliability.

Notes: Conclusions 1. The rock foundation of the Sayano-Shushenskoe dam is inhomogeneous in its seepage characteristics: individual stretches in zones of tectonic crushing of the rock are the most permeable. 2. The depth of opening of the rock-concrete contact does not exceed 27 m. 3. During 4 years each subsequent filling of the reservoir to the NPL intensified the degree of decompression of the foundation, involving the deep curtain in this process. Signs of cracking of the middle part of the grout curtain were detected. It is necessary in the very near future to take measures to suppress seepage through the rock foundation.

Notes: Conclusions 1. In connection with the fact that potentially unstable masses exist in the immediate vicinity of the dam and powerhouse, which are referred to as Class I structures in terms of capital expenditures, the approach taken for the design of PUM stabilization should be nonstandard with consideration given to a number of permanent vibratory design loads introiduced by operating hydraulic units and spillways, as well cyclically varying loads due to the weight of the water in the reservoir and the weight of the structures. 2. It is proposed to define the volumes required for PUM stabilization of the left-bank slope more precisely on the basis of observations of PUM during construction and operation of the hydroelectric plant. The interruptions that have occurred in the instrument observations should therefore be recognized as impermissible. 3. Construction and operating experience has demonstrated that it is expedient to perform work on stabilization of potentially unstable masses prior to the start of construction on entities located in their immediate vicinity. 4. A protective rock wall built at the foot of the slope cannot provide for the complete safety of the structures located close to the left-bank slope during the collapse of rock blocks or individual stones. 5. On-going monitoring of the condition of the left-bank slope does not correspond completely to problems of providing for the safety of the structures and personnel at the hydroelectric plant by reason of the low reliability of the measuring equipment. 6. Use of the automated “Relos-L” system for observations of the condition of the rock masses will make it possible to carry out continuous on-going monitoring within the framework of the automated production-control system at the Sayano-Shushenskoe hydroelectric plant. Only a multifunctional monitoring system, which includes different kinds of independent observations, can provide a sufficiently valid evaluation of the state of the PUM, and, on their basis, determine measures to prevent possible emergency situations. 7. The collapse of PUM in the initial stage of construction with subsequent plaining of the slope and the organization of multistory rock-entrapping benches is a more reliable, safe, and, probably, economical (if expenditures for future operation are assumed in the calculation) method than their stabilization.

Notes: Conclusions 1. The plan of arrangement of the monitoring and measuring instruments on hydraulic structures of the Sayano-Shushenskoe hydrostation, developed on the basis of an approximate calculated prediction of the SSS of the dam — foundation system without consideration of the technology of constructing the dam and structural and tectonic features of the rock foundations did not meet the requirements of present-day monitoring and needed substantial expansion. 2. The installation of additional measuring instruments was done with consideration of the real scheme of the static behavior of the dam and foundation and with consideration of the need to monitor the technological measures being taken to restore the solidity of the dam and foundation. 3. Nontraditional approaches to problems of monitoring hydraulic structures, automation of on-site observations, and the development and introduction of information display programs made it possible to increase the reliability and promptness of monitoring and to monitor the state of the dam at a modern level.