Method of calculation and design of the ice and thermal regime of the lower pools of hydroelectric stationsSkladnev, M.; Lyapin, V.; Pekhovich, A.; Razgovorova, E.
doi: 10.1007/BF01428577pmid: N/A
1.
The problem of calculating and predicting the ice and thermal regimes of modern large hydrostations being created, especially under northern climatic conditions, is important for solving many problems having national economic and nature conservation significance. The solution of the problem of reliable prediction of ice and thermal regimes in lower pools of large hydrostation is of particular interest and significance.
2.
The presently existing methods of calculating the ice and thermal regime of pools of hydrostations are approximate and have been developed mainly with regard to the operating conditions of particular low- and medium-head hydrostations located, as a rule, in the temperate climate zone. They insufficiently take into account the specific characteristics of the physical phenomena governing the formation of the ice and thermal regime in lower pools.
3.
As shown in the article, on the basis of an additional thorough study of physical phenomena with the use of data of actual observations it is possible to give a reliable picture of ice and thermal processes in lower pools of hydrostations, including those located under northern climatic conditions. With the use of the theory of heat transfer and refinement of the heat-balance equations analytic and graphic relations were obtained which permit determining the main characteristics of the ice and thermal regime in various stretches of the lower pool, longitudinal and vertical temperature distribution of the flow, and formation of frazil and the ice cover.
Hydrotechnical concrete of the Ust-Ilim hydroelectric stationSadovich, M.
doi: 10.1007/BF01428578pmid: N/A
1.
A decrease of cement contents compared to analogous compositions of the Bratsk hydrostation, improvement of concrete quality, and increase of general technological discipline attest to definite progress in the technology of hydrotechnical concrete at the Ust-Ilim hydrostation. Further progress is associated with the selection of a rational technology on the basis of the experience of the Bratsk and Ust-Ilim hydrostations, modernization of individual components, and creation of a system of automatic compensation of the variability of the moisture content of aggregates at concrete plants, mechanization of concreting operations in the blocks, and increase of general efficiency.
2.
Site tests of the concrete of the Ust-Ilim dam and the results of observations of seepage through the concrete of the upstream face showed that the solid concrete mass is practically impermeable and the relatively small seepage flow occurs along cracks and horizontal joints. One of the directions of the rational use of concrete can be a further reduction of the cement contents in concrete of the upstream column to an extent which does not cause damage when used as a material and will promote an increase of crack resistance of individual blocks and structures as a whole.
3.
An analysis of the results of testing control samples and visual observations of the state of concrete surfaces showed that when assigning the concrete composition it is absolutely necessary to take into account the conditions of hardening of the concrete in the structure. In massive and underwater structures concretes with low cement contents harden most intensely and for the longest time. The strength reserves occurring in this case remain, as a rule, unused. In outer surface zones, conversely, early drying and other unfavorable factors can lead to a decrease of the potential possibilities of concrete.
4.
The prescribed technical parameters of the concrete of the spillway surface and variable-level zone were completely provided as a result of introducing a number of measures: blending of special compositions, development of technology of placement, etc. The wider use of rubble in especially important concretes is characteristic for the Ust-Ilim hydrostation as a whole.
Experimental investigation of deformations and bearing capacity of sand foundations of retaining structures by the rigid plate shearing methodKashkarov, P.
doi: 10.1007/BF01428580pmid: N/A
1.
The bearing capacity of sand foundations of plates and their horizontal displacements are described by generalized graphs of the relation
$$N_{\tau _{ul} } = f(N_\sigma )$$
and
$$u_{ul} /B = f(N_{\tau _{ul} } )$$
, which is confirmed by the validity of the similarity parameters of the state of stress and strain of the foundation.
The relations obtained indicate the possibility of conducting field experiments with small plates, for example, with a width of 0.7–1.0 m, which considerably reduces material and labor expenditures.
2.
The aforementioned graphs are different depending on the state of the soil. The bearing capacity of the made-ground foundation is considerably less than that of an undisturbed foundation. In the first case the initial section of the graph
$$N_{\tau _{ul} } = f(N_\sigma )$$
, within which the plate shifts along the plane, is limited by a critical modeling number
$$N\sigma _{cr} \cong 1.0$$
. According to the results of field investigations it was
$$N\sigma _{cr} \cong 4.0$$
.
The revealed circumstances permit using the indicated graphs differentially as the maximum possible with consideration of the sensitivity of the soil.
Optimization of dredge and variable displacement pumpsKhlopenkov, P.
doi: 10.1007/BF01428583pmid: N/A
1.
Centrifugal pumps with an adjustable outlet diameter and width of the impeller passage and discharge pipe improve the operation of the netweork and make it possible to reduce energy expenditures at pumping stations by 10–20%.
2.
By obtaining clean water directly from the sludge and directly in the pump (without pressure losses) it is possible to solve the problem of protecting pump elements from abrasion by a wall boundary layer without increasing energy expenditures on injecting clean water into the internal cavity of the pump.
3.
By fractionation of sludge in pressure settling tanks (without pressure losses) it is possible to use inferior borrow pits near hydrotechnical construction sites for reducing transportation expenditures on delivering inert materials to the site.
Experience in operating large seawater intakesKuzovlev, G.
doi: 10.1007/BF01428584pmid: N/A
1.
Modeling of the cooling capacity of a water area without consideration of the weather and ice conditions does not give a true picture of the distribution of water temperatures. In connection with this, the data of modeling can be regarded only as a first approximation.
2.
Dams with a gravel-sand foundation can operate reliably without constructing a stone bed.
3.
Heating of the water at the intake in the winter, especially in the period of shuga formation, increases the reliability of operation of the power station.
4.
When designing intakes it is necessary to take into account drift, gradient, and longshore currents.
5.
Observations conducted at the Caspian intake show that dust particles falling on the surface of the canal are removed from the canal by the flow and the canal is not silted.
6.
Cuts beyond the limits of levees are quickly filled with sediments and their construction is not advisable.