The complex of structures of the Sayano-Shushenskoe and Maina hydroelectric stations on the Enisei River has a total volume of concrete of about i0 million m 3. The aggregates for the concrete are prepared by sorting a sand-gravel mixture at the gravel-sorting plant (GSP) located 40 km from the site. The quarry, representing ancient deposits of the Enisei River, is located 2 km from the GSP and the deposits are characterized by a variable particle-size distribution of the material in different sections~In this case, sections of sands with a fineness modulus Mf from 1.4 to 2.9 and in lenses from 1.0 to 3.1 (sometimes more) are found.In the initial stage of construction selective excavation of the quarry was accomplished, but with an increase in the rate of concreting and working of the quarry it was necessary to use all sections, including with finer sands. An analysis of sands obtained from different sections of the quarry showed that each section of the quarry has an average size of the sand, in which case the deviations of particular samples, as a rule, do not exceed • unit of the fineness modulus (Fig. i).The available instruments do not permit a prompt particle-size analysis of the sand during its delivery to the mixers.Investigations of the characteristics of sand over a long time showed a stable relation between Mf, weighted average graindiameter, and specific surface of sand for the entire deposit (Fig. 2). A Stable relation is absent between Mf and the volume of voids of sand, although there is a tendency toward an increase of the volume of voids with decrease of Mf. To obtain the indicated relations between Mf and the specific surface and weighted average diameter of the grains, several dozen sand samples taken in different years of construction from different sections of the quarry were analyzed.The specific surface of the sand was determined by the known formula Ssp= (16,5K/lOOO)(o+2b+4c+8d+16e+32f),(i) where a, b, c, d, e, f are particular residues smaller than 2.5 mm on the sieves and on the tray; K is a coefficient taking into account the grain shape (in the given case taken equal to 1.5).The adopted technological scheme of the gravel-sorting facilities does not permit averaging the sand by size due to such large time intervals which would permit considerable smoothing of the variations of size during excavation of different sections of the quarry.The original selection of the compositions of the hydrotechnical concretes was performed by the B. E. Vedeneev All-Union Scientific-Research Institute of Hydraulic Engineering (VNIIG) with sands with Mf = 2.3-2.5. The production compositions of the concrete, corrected by the construction laboratory on the basis of the compositions and with the participation of VNIIG, were used for several years, were perfected, and had a comparatively low content of cement (Table 1 for Mf = 2.0-2.4), Beginning in 1979 a decrease in the size of the sands being used at first to Mf = 1.8 and then to Mf = 1.4-1.6 with considerable variations was observed, since different secti...
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