Showing papers in "Hydrotechnical Construction in 1970"

The effect of aggregate size on strength and deformation of concrete

Abstract: Increasing the granular composition of the aggregate increases the efficiency utilization of cement in concretes working in compression. At the same time, there is a reduction in deformation and an increase in Young's modulus and unit weight of the concrete. The tensile strength of the concrete is severely affected by increasing the size of the aggregate. On increasing the maximum grain size to 120–180 mm, the reduction in tensile strength is 30–50% as compared with concretes with maximum aggregate size 20 mm. There is also a reduction in the elongation limit. On increasing the aggregate size, homogeneity of the concrete deteriorates, and the values Rp and Rpb approach each other, even on specimens of the same cross-sectional dimensions. When designing concretes for given strength and deformation properties, the coarseness of the aggregate is one of the most important technological parameters.

Deformation of rock foundations of high dams after filling the reservoirs

Abstract: 1. Complex compressive and tensile deformations occur in the foundations of high dams, caused both by the loads from the installations and (to a greater extent) by the weight of water in the reservoirs. These have to be taken into account in the static calculations and model investigations into stability and stress of dams and their foundations. 2. In the relief and deconsolidation zones, the properties and behaviour of the rock masses differ substantially from those in the rock masses loaded and compressed from all sides outside these zones. In the first case, the rock mass must be considered as a system of blocks of different shape and size, interacting along the boundary surfaces and contacts. In the second case the rock mass is considered as an elastic medium, characterized by relatively high values of C, and capable of resisting the total and tensile stresses; fissuring, with the exception of individual breaks in continuity, is largely reduced to a minimum. 3. The detection and plotting of the deconsolidation zones of rock masses is one of the most important problems of prospecting and investigation of the foundations of high dams. 4. The principles governing the behaviour of rock foundations of high dams under the action of external loads, depending on a number of factors, have so far been little studied. Theoretical and experimental forecasts frequently diverge substantially from the actual.

Shear strengths of fissures in ledge rock before and after grouting

Abstract: 1. Cement grouting of fissured ledge rocks leads to a marked reduction in slip deformation due to an inclined load. The effect of cementation is most marked in badly fractured rocks, the slip of which in the natural state is characterized by an elongated horizontal-displacement graph. 2. Cement grouting leads to an increase in the shear strength of hard rocks. Cementation is most effective in badly fractured rocks without fine earth filling, owing to the efficient filling of the cracks by the cement solution. (We must, however, remember that such conditions are not always found in natural rock masses.) 3. The use of cement solutions based on dispersed cement (colloidal cement or dry-vibromilled cement) permits cement grouting to be more effective than with ordinary cement. 4. The presence of badly broken sections in a rock foundation is not necessarily a reason for reduced slip resistance parameters or for removal of much of the rock, and in such cases we should always consider whether it is advantageous to use cement grouting to improve the quality of the rock.

Engineering-geological conditions of the construction of the Plyavin'sk hydroelectric development

Abstract: With respect to the complexity and uniqueness of the engineering-geologic conditions, the structures of the Plyavin'sk hydroelectric station do not have analogs either in domestic or foreign practice of hydraulic engineering on soft foundations. The geological surveys and investigations during the 12 years of planning, constructing, and operating the hydroelectric development yielded reliable data for engineering solutions of the development and its structures, the expendiency and reliability of which are confirmed by the operational data. The construction of the Plyavin'sk hydroelectric development under complex engineering geological conditions was a school of valuable experience in the field of engineering geology.

Results of field observations on ice passage through the structures of the Krasnoyarsk hydroelectric plant

Abstract: The field observations at the construction site of the Krasnoyarsk hydroelectric plant and data on the passage of ice at other Siberian hydraulic complexes permitted us to obtain relationships for the computation of the ice passage conditions for the designs considered and to estimate quantitatively the effect of some factors which facilitate the conditions of the passage of ice through unfinished structures. However, many problems related to the retention and passage of ice through structures are not yet solved. Therefore, further field observation on the passage of ice at the hydraulic complexes under construction on rivers with intensive spring runs are necessary.

V. I. Lenin Plyavin'sk hydroelectric station in the Latvian SSR and its operation

Abstract: 1. The possibility of constructing hydroelectric stations with heads up to 40 m on soft ground was proved by the construction of the Plyavin'sk station. 2. The block-type powerhouse is economical with respect to investments and provides normal operation of the main and auxiliary water-power equipment. 3. The Plyavin'sk station is justifying the power functions imposed on it: participation in coverage of the peaks of the load schedule, regulation of the load deviations, and emergency and frequency reserve of the Northwest grid system. 4. The Francis turbines regulate the active load of the station by the number of units turned on.

Experience in the operation of the structures of the Kama hydroelectric station

Abstract: 1. The many years of operation of the Kama HES proved its dependable work in the Permenergo system. Stream-flow regulation by the Kama Reservoir ensured additional output of electric power at the downstream power plant. 2. The engineering-geologic conditions of the Kama HES, characterized by the presence in its foundation of gypsum and salt-bearing formations that can be dissolved and leached out by the seepage flow, are unique. 3. The correctness of the design of the underground contour of the spillway was confirmed during the operation period. 4. The density of the grouted curtain wall diminished at individual places during the operation period. Dissipation of the pressure head occurs in the natural upstream floor and increases with time. 5. Experimental operation of the deep vertical drainage shows that the drainage reduces the pressure head in all three water-bearing strata and increases the stability of the structures. However, considering that with the present state of the foundation the stability of the HES is assured without the operation of the vertical drainage, and in view of the inadvisability of increasing the ascending seepage flow and of drawing in aggressive water from the joints, and of the increase in the settling of the structures caused by its operation, the vertical drainage should not be connected at the present time. 6. The structures of the Kama HES operated dependably during the operation period which began in 1954.

The Atbashi hydroelectric station

Abstract: 1. As indicated in the project design, it is possible to erect dams without coffer dams, excavation, and dewatering, i.e., without excavating the river bed alluvium on mountain streams, similar to the Atbashi River. The watertight structures in the submerged section of the dam can be made by cementation of the alluvium and core of the dam. 2. When the stream has a large silt burden, which will rapidly silt a canyon reservoir, it can be used as a settling pond with periodic annual deep flushing. The system of operating the reservoir which has been adopted eliminates the necessity for constructing the ordinary type of settling ponds, which is impossible or very difficult in canyon stream beds.

Engineering geology properties of the foundation soils of concrete structures at the Kanev hydroelectric development

Abstract: 1. The complexity of the engineering geology conditions of the area of the concrete structures of the Kanev hydro development, especially the foundation of the hydroelectric station, which is due to the variegated geologic structure and inhomogeneity of the indexes of the physical, mechanical and seepage properties of the soils, is explained by the peculiarities of the formation of the thick stratum of Quaternary deposits and complex character of development of this segment of the valley of the Dniepr River. 2. In connection with the aforementioned peculiarities of the geologic structure and the imperfection of the rock-drilling technique used in the investigations, a number of engineering-geology problems of the foundations (distribution of weak soils, natural density of the flooded sands, etc.) were solved conclusively only during the period of geologic documentation of the foundation pits. 3. The presence of weak soils in the stratum of the station foundation often necessitated the use of additional measures when preparing it (removal of weak soils, compaction of sands having an insufficient density, etc.).

Grouting the joints of the Krasnoyarsk hydroelectric-station dam

Abstract: 1 The constructional decision adopted for preparation of the placed concrete for the dam and for rendering it monolithic made it possible to carry out properly-timed grouting of the structure 2 The insufficient opening of individual joints led to additional expenditure on their grouting 3 In order to produce an optimum opening of a joint it is expedient to stipulate the distance between joints as not less than 13 to 15 m 4 The progressive variation of the temperature of placed concrete does not fully reflect the nature of the joint opening In order to obtain more complete data on opening of the joint, it is necessary to install telemetered joint gages in those zones of the structure which are characterically representative of the concrete placement and cooling procedures 5 The working pressure in the joint during the grouting period should be specified according to the deformations permissible

Mechanical equipment and its assembly at the Krasnoyarsk hydroelectric station

Abstract: 1. Steels 09G2, 09G2S, and 138IZ delivered as sheets in a standardized and improved state with a guaranteed impact strength norm at temperatures from \t-40\dg to \t-70\dgC are among the most reliable steels, other conditions being equal, and therefore are recommended for the manufacture of mechanical equipment and metal structural members of hydraulic structures constructed in regions where the air temperature is below \t-40\dgC. 2. The deep gates, intended for operation during the construction period, should be designed on the basis of the norms for the designing of service gates, their manufacture should be accomplished within the allowance accepted in machine construction, and careful work is required during their assembly. 3. The quality of the assembly and welding of the aeration tubes should be high, and all welds should be strong and tight to prevent entrance of cement mortar during injection. Before concreting the aeration tubes, the tightness and strength of the welds should be checked hydraulically. li]4.|A high efficiency when constructing the penstocks can be achieved only by reducing the entire assembly cycle: a) by introducing effective welding methods; b) by using highly productive specialized and universal assemblywelding machines. The well-developed technology of enlarging and assembling penstocks, the construction of a yard for consolidating the links of the pipe line and other structural members and equipment, the creation of a shop for assembling and automatic welding andx-ray inspection, the development of special devices and properly selected equipment of the welding shop (stands for welding straight links and elbows, flux cushions, bridge crane, etc.) have made it possible to industrialize and shorten the period of installation of the pipe lines and to improve considerably the quality of the work. 4. The use of 50-ton tower cranes along the route has greatly facilitated the assembly of the links of the pipe lines and reduced the time of their assembly. 5. The rather simple and fast method of raising the tower cranes from one level to another, which was mastered by \ldGidromontazh\rd Trust, made it possible to perform concreting on the dam successfully. 6. Of particular value is the use of concreted seats at the final state of construction under conditions of a flooded pit and successive startup of the turbine-generator units, when the front of the works and the area of the construction site are being reduced markedly. Industrialization of all work at this stage largely compensates for reduction in the construction rate which is inevitably caused by los, of communications and production areas.

Static stress calculations for dock structures considering wall-backfill interaction

Abstract: 1. The suggested method for static calculations of dock structures considers the entire structure and enables us to take into account the interaction between the wall and the backfill. The method admits of variable stiffness for foundations and structural elements. 2. The calculations aim at formulating and solving a system of standard linear equations, and the procedure for forming the system is sufficiently simple for practical application in engineering designs. 3. Calculations show that for wide, flat structures of modern dry docks, wall-backfill interaction has considerable influence even for relatively low walls (when compared to sluices). The wall behavior has a significant influence on foundation deformations. This influence is greater as the relative foundation stiffness increases. 4. Results of calculations for determining the total lateral pressure on dock walls (Fig. 2c) qualitatively agree with the field observation data on sluice walls [7, 8, 10]; the pressure considerably increases in comparison to the Coulomb method and the pressure diagram centroid shifts upwards.

Optimum operating conditions of a hydraulic lift in a pressurized hydraulic transport system

Abstract: 1. The operating conditions recommended in the literature for hydraulic lifts in pressurized hydraulic transport systems are not usually the optimum. 2. The most suitable in respect of energy consumption is the dry charge conditions of the hydraulic lift, since the ratio of solid to liquid components must correspond to optimum consistency of the hydraulic mix in the pressure pulp line.

Method of determining the bearing capacity of anchor foundations in rockfree soils

Abstract: 1. Kananyan’s calculation scheme and Eq. (1) for determining the bearing capacity of deep anchor foundations (λ ≥ 5) give a substantial overestimation when changing from model to actual conditions, and therefore require refinements. 2. To adapt the indicated calculation scheme to the actual working conditions of anchor foundations it is necessary to reduce greatly the design depth of the upward yielding funnel hcr and to take not more than 4–5d for sands and sandy loams. 3. Equation (1) should be brought into correspondence with the actual working conditions of the soil in the case of upward yielding, so that it takes into consideration the distribution of the soil’s weight that is involved in friction and the part that is transmitted directly to the anchor foundation during upward yielding.

Experience with the damming of the right arm of the Volga river during the construction of a stream separator in the delta

Abstract: 1. The combination of hydraulic filling with and without the protection of a rock banquette is convenient and economical. Hydraulic filling without the use of banquettes is recommended for average velocities not exceeding the values obtained from Eq. (5). 2. The preliminary protection of the river bed at a site where damming work is to be carried out does not always prove to be effective. Under average velocities exceeding the values obtained from Eq. (5), small local rubble fill protections are destroyed. In case it is necessary to place preliminary protection on the river bed, the existing recommendations may be used [5]. 3. The empirical relations presented here may be recommended for preliminary calculations relating to damming work to be carried out under conditions similar to those of the problem discussed.

Hydromechanical equipment of the V. I. Lenin Plyavin'sk hydroelectric station

Abstract: 1. The hydromechanical equipment of the upper and lower pools of the Plyavin'sk hydroelectric station on the whole reliably ensures the operation of the development under all conditions. 2. The single-sluice working and emergency gates deserve a favorable evaluation. 3. The grab beams require reconstruction, since they presently work unreliably. 4. Under operating conditions large expenditures are needed for maintaining the anticorrosion coatings of the equipment.

Overall scientific research in the USSR in the field of hydropower construction

Abstract: 1. The development of overall scientific research in the USSR for the justification of design and construction of hydraulic engineering and hydropower installations is inextricably linked with bringing to life the Go\'elro plan in the field of hydropower and water supply, the five-year plans for the development of the economy, and subsequent large-scale plans for the multipurpose utilization of the water resources of the country. 2. Overall scientific research in the field of hydraulic engineering and hydropower brings out all aspects of the performance of future installations and the multiplicity of the phenomena and processes occurring. This type of research has enabled Soviet experts to resolve many problems in hydraulic engineering construction and to introduce new types of hydraulic installation on soft and rock foundations, employing advanced methods of organization and performance of construction, taking into account the special climatic conditions and unique nature of the installations. Overall investigations have resulted in advances in Soviet hydraulic engineering science with respect to a number of problems. On the basis of these investigations, big engineering advances have been made in Soviet hydraulic construction. 3. Large-scale overall investigations have brought about substantial savings in construction, amounting to 10% of the cost of a hydroscheme. 4. The work carried out throughout the country in the coordination of scientific work in the field of hydraulic engineering and hydropower has resulted in more effective and clear-cut organization of overall scientific research, as regards both extending the range of problems studied and the composition of the teams, and with respect to the time taken to complete the work and apply the results, and with respect to optimum utilization of the available key scientists and experts, research, stations, and their equipment. These facts are very important considering the scale of hydraulic engineering construction at present and in the future in the Soviet Union, for meeting the needs of all branches of the economy, including power, agriculture, industry, fisheries, transport, etc.