The Kettle Rapids hydro development is being constructed in Canada in the northern part of Manitoba on the Nelson River, 105 krn from Hudson Bay. It is planned to construct 12 hydroelectric stations with a total installed capacity of 7200 MW on the Nelson (length 600 km), flowing from Lake Winnipeg, and its tributaries. The largest in the sequence will be the Limestone station, with a capacity of 1800 MW. At present the 338-MW KeRsey station is in operation and construction of the 1220-MW Kettle Rapids station is being completed. The hydro development is being constructed under cold climatic conditions in a region of insular permafrost. The climate of the construetion region is subarctic, temperate-continental with a large temperature range and small precipitation depth. The mean annual temperature is -5"C, minimum winter-49.5*, and maximum summer 32.3~ there are about 100 frost-free days during the year. The mean annual rain depth is 0.31 m and snow, 1.26 m. The average flow of the Nelson at the site of the hydro deveRopment is 2200 mS/see.The structures of the hydro development ( Gneissic rocks occur in the powerhouse foundation (Fig. 2) and spillway and sand-graveR soils In the foundation of the earth dam (Fig. 3). The presence in the foundation of permafrost with ice interlayers and also of weak zones in the pit of the earth dams required removing the weak rocks and ice to a depth of 15 m and installing sandfilled vertical drain wells.The planning and surveying work was begun in 1962 with the scheme of using the Nelson River. The plan of the Kettle Rapids hydro development was drawn up in 1965-196"/and its construction begun in 1966 with the construction of a temporary village, roads, and temporary facilities. The flat terrain, layout of the hydro development in which the concrete structures (powerhouse and spillway) are adjacent to the right bank, and the main approaches to the hydro development predetermined the right-bank location of the entire construction site and residential village.

Hydraulic construction experience gained during the last few years bears witness to the development of construction of embankment dams, whose cost can be substantially reduced through suitable organization of the construction work and me of modern progressive equipment, especially for transporting materials. A summarized description of the earth-rock work volumes for some embankment dams is presented in Table i [9].The volumes of earth--rock work at five of themost representative quarries of nonmetallic materials of the Ministry of Power and Electrification (Mindnergo) of the USSR amounts to 1.5-2.5 million mS/yr at each enterprise. The haul distance for earth--rock materials from the quarries to the embankment dams is usually in the 3-5-km range, and the haul distance for the rock to the concentrating plants processing it is of the order of 2-a km. Up to the present time, earth and rock for construction of embankment dams. as well as nonmetallic materials from quarries, have been transported by dump trucks, up to 27 tons in carrying capacity, at a haulage cost of 12-15 kopecks/ton-kin. This makes it necessary to construct and maintain costly roads with rigid pavements, especially for large-capacity machines, as well as to construct and maintain maintenance-mechanical shops, filling stations, fuellubricant storehouses, and other service enterprises. Truck transportation calls for a large number of workers, especially drivers, and. consequently, for increased construction of residential buildings and enterprises for these personnel.In the construction of embankment dams, thc cost of hauling earth--rock materials may amount to up to 60% of their total cost. This situation occurs to the same extent in the quarrying of nonmetallic materials. In the last few years, in Soviet and foreign practice, to transport rock from quarries to concentrating--grading plants, as well as stripped soil to dumps, along with truck transport use has been made of conveyors. The operating e~cperience of several mining enterprises in the ferrous and nonferrous metallurgical industries, construction materials enterprises, and coal industzy enterprises indicates that conveyor transport exhibits various substantial technicoeconomic advantages in comparison with truck transport [1][2][3] 7]: The demand for workers is reduced (on account of the decrease in the number of operating persons); the number of trucks is lowered; the transportation cost is reduced by a factor of 1.5-2; the labor productivity of the persormel is considerably increased; progressive flow-line techniques are introduced in earth--rock work in the quarry--dam line in the construction of embankment dams, and in the line from the quarry to the crushing--grading plant in the exploitation of nonmetallic materials; the coefficient of utilization of the main mining equipment is increased through reduction of the dead time of the equipment in the flow-line method; and possibilities are opened up for reducing the transportation distance of the mined mass to the ground surface on acco...

Over the years of the Soviet regime, hydropower has grown from the stage of the firstlings of hydropower construction, such as the V. I. Lenin-Volkhov, Boz-Sui, and Zemo-Avchalsk plants, to the unique hydraulic developments of the present time, which have the world's highest dams: the embankment dam of the Nurek plant, and the concrete arch dam of the Inguri plant. This became possible thanks to the development of new methods of structural analysis using electronic computers, introduction of modern, highly efficient methods of construction, and extensive experience acquired during construction of large Soviet hydraulic developments, both on plains rivers with soft foundations and on mountain rivers.It is especially important to point out the advanced experience acquired from year-round construction in the Far North and permafrost regions.At the present time, concrete is being placed over a wide front at the startup construction projects of the Tenth Five-Year Plan --the Sayano-Shushenskoe and Inguri hydroelectric plants. Also, construction is being started on the Kolyma, Kurpsa, Rogun, Bureya, and Boguchany hydroelectric plants, most of which are of the multipurpose type, as well as on the Zagorsk and Kaishyadoris pumped-storage plants. Along with improvement of the constructional solutions for the main structures, in the near future the basic trend in the improvement of hydrop0wer construction will continue to lie in the introduction of better methods of building them.A significant share in the improvement of the effectiveness of construction work lies in the reduction of labor costs. Thanks to the use of integrated mechanization, a high labor productivity has been achieved at several construction projects.At the massive Toktogul dam a method was worked out and introduced for layer-by-layer placement of concrete in large blocks by applying a special, fully mechanized technique which makes it possible to increase the concreting labor productivity to 11-13 mS/man-day as against the previously achieved figure of 4-5 mS/man-day.At the Chirkey arch dam, through delivery of the concrete by 25-ton cableways and use of integrated mechanization the labor productivity was brought up to 10-11 mS/man-day.The use of heated forms, tents, and various other measures made it possible to place concrete during an entire cold winter in the Ust-llim and Zeya dams. The successful construction of hydraulic developments in the Far North regions has been considerably aided by the new methods of year-round construction of embankment dams, developed by the Gidroproekt Institute jointly with the constructors, which have made it possible to successfully build the impervious elements of the Vilyui, Ust-Khantaika, and Serebryansk dams during the winter. Still wider possibilities for construction of hydraulic developments on large rivers have been offered by the passing of flows during construction over the uncompleted rock--earth Ust-Khantaika dam. A new improved technology made it possible to achieve great successes in the construction of th...

The problem of manufacturing precast reinforced-concrete elements of penstocks with an inside diameter of 7.5 m for a design pressure of 1.7 MPa was solved in the USSR for the first time and, naturally, challenged designers with a number of problems.As a result of generalizing foreign and Soviet experience in the manufacture of pressure pipes it was decided to use the unit-line method. With consideration of the dimensions and mass of the precast reinforced-concrete element and the limited number of elements being manufactured for a particular pumped-storage station (PSS) in a construction period lasting 3-4 years, it was decided to manufacture the precast reinforced-concrete elements under casting yard conditions in an open area.Work on designing the mechanized technological line necessitated solving the following main problems: method of casting the elements; method and regime of compacting the concrete mix; selection of the composition of the concrete; method of heat treatment and the thermal regime; organization of works on anticorrosion coating of the inside lining of the conduit; possibility of combining the process of maturing and anticorrosion works to shorten the manufacturing cycle; method of quality control of the articles; creation of an industrial experimental casting yard at the construction site of the Zagorsk PSS; creation of nonstandardized equipment for the yard; debugging of the equipment and improvement of the technological processes under production conditions. The All-Union Planning, Surveying, @nd Scientific-Research Institute (Gidroproekt), research department of Gidroproekt, mechanical department of the special design bureau of Gidroproekt, and alsothe Moscow Special Design Department for Steel Hydraulic Structures (Mosgidrostal') and the All-Union Trust for the Protection of Power Equipment (Soyuz~nergoza-shchita) participated in solving these problems.Considerable work on the part of the research department of Gidroproekt preceded the selection of the main technological solutions regarding the compositions of the concrete and method of heat-treating the elementS.The choice of the unit-line method of manufacturing the precast elements was dictated by the need to cast the element at one or two stations with further transfer of the cast article to the maturing station. The casting station is a resonance platform vibrator having a load capacity of 200 tons with horizontal circular vibrations.The metal formwork with the reinforcement frame and lining wrapped on the molding drum is placed vertically on the platform vibrator.The reinforcement frame is made at a special yard and hauled in a finished form to the casting station.The concrete is placed by 3-m 3 bucketsby means of a 10-ton-capacity gantry crane with delivery of the concrete into themoldthrough a special distributing device. The total volume of concrete in the element, 48 m 3, is placed in four layers with a height of i.i m each. The concrete mix is compacted during unloading of the buckets. After placing the last bucket the distribu...

One of the questions discussed at the Twelfth Congress was devoted to the construction of earth dams and especially to the use of low-grade materials; construction of slurry ponds and water pollution during their operation, and also to new materials and methods of dam construction.These were discussed in 44 reports from 27 countries. In addition, 12 general reports of national committees were presented. USE OF LOW-GRADE MATERIALSTwelve reports reflected the need to extract dam construction materials from useful excavations and from borrow pits located close to the dam in order to increase the economy of construction.The use of low-grade materials of a far from optimal granulometric composition, containing weak broken inclusions with a water content differing considerably from the optimal, creates certain difficulties in constructing embankments and in some cases leads to an increase in the volume of fill needed to provide stability of the dam.Therefore, when designing dams using low-grade materials special attention is paid to a study of the effect of the foundation on the dam's design, reliability of the design in the presence of settlements during construction and operation, selection of the materials, construction and control methods, design of the drainage system, and to means of eliminating pore-water pressure and determination of its effect on the stability of the structure.