Condition of the thrust front of the Sayano-Shushenskaya HPP after completion of repairs to reduce its perviousness

Abstract

It is required to regulate filling of the reservoir with consideration of the temperature field of the structure.The Sayano-Shushenskaya gravity-arch dam has been in service in the design mode since 1990. During the 16-year period of normal service, it has been repeatedly subjected to large-scale technogenic effects. The most significant of these has been repair work performed to eliminate seepage within a zone of cracking of the first column of the dam between elevations 344 and 359 m. This work was conducted in 1996 in the concrete of the thrust face in sections 19, and 21 -46 at high upper-pool levels (UPL) using "Rodur" twocomponent epoxy resins [1,2]. Injection of the loosened rock bed of the channel dam with a material of similar composition was carried out during the period from 1998 through 2003 [3]. Work on restoration of the anti-seepage properties of the upper portion of the deep grout curtain was conducted in several stages: under sections 40 -42 in 1998, sections 26 -29 in 1999, sections 30 -39 in 2000, sections 15 -25 in 2001, and under sections 43 -48 in 2002 and 2003. In each of the stages, the repair work was done in two phases: first phase -at minimum upper-pool levels; and, second phase -with the UPL close to maximum. Individual subhorizontal cracks with the greatest seepage, which were situated within the concrete of the first column between elevations 374 and 386 m (upper zone of cracking) were subjected to "medical treatment" in 2004. In 2006, work involving repair of a permeable section of the right-bank grout curtain, which was located between elevations 344 and 413 m, was begun during the stage of the reservoir's filling.Timely repair operations within the concrete of the thrust face and bed of the channel dam using non-traditional procedures and materials made it possible to achieve the following expected results:-heavy seepage through the cracked section of the thrust front between elevations 344 and 359 and 359 and 386 m has been suppressed; residual seepage flows have amounted to 5 liters/sec (1996) and 8.5 liters/sec (2004), whereas their maximum values in the periods prior to the repair had been 458 and 55 liters/sec, respectively; -the concrete in the lower section of the thrust face has been pressed in the cantilever direction, and residual additional compression has amounted to from 1 to 2 MPa; and, -seepage flow within the bed of the channel dam has been reduced from 549 (1996) to 50 liters/sec.In individual years of the repair and post-repair periods, the conditions under which the reservoir has been filled have been characterized by a large influx in different stages of the rise in the UPL, and prolonged maintenance of high levels at elevations close to the normal backwater level (NBL). In 2001 and 2004, the maximum rate of filling of the reservoir reached 1.9 m/day. After a rapid increase in hydrostatic load occurs during sudden filling of a reservoir, the temperature of the concrete in the downstream face does not have time to rise significantly. And, radial displacements...

The bed of the sayano-shushenskaya hpp: structure, properties, and condition

“…According to [12], residual tension-induced displacements over the control 30-meter depth of the rock mass increased every year in the post-repair period -maxi- After the "therapy," the total filtration flow rate through the bed and banks decreased markedly (Table 2), whereupon 80% of the flow had to travel through the powerhouse and left-bank sections. Work involving restoration of the grout curtain in the left bank (the grout curtain in the right bank had been previously restored) was performed in 2008 -2009. According to data derived by E. G. Gaziev (2001Gaziev ( , 2002, both abutments are deforming, whereupon the residual deformations have become appreciably lower as compared with those in the 1990s: after one year, they did exceed 2.5 × 10 -5 in both the left, and also right banks.…”