The concrete gravity dam of the Krasnoyarsk hydroelectric station [1, 2,3] has an overall length of 1100 m, a maximum height of 120 m, and a placed-concrete volume of nearly 5.7 million m s, including 4 million m s to be rendered monolithic (see Table 1).The dam is divided by permanent joints into 75 sections, spaced 15 m apart in the river portion and 7.5 m in the parts abutting the river. Each section is divided by temporary joints, spaced generally 11.5 m apart. Thus, the structure is built up in columns 15 m by 11.5 in plan. The block lift height was planned to be 3 m, but up to 30 % of the placed volume was concreted in blocks of 5 to 9 m height. The columns and their intervening joints are constructionally of the same type for the nonoverfall, spillway and hydrostation dams (Fig. 1).In order to establish a monolithic dam section, the intercolumn joints formed by cooling of the placed concrete must be grouted. The joints between the sections are grouted only within the limits of the first (i.e., upstream) column to improve sealing.In what follows, an examination is made of some problems in the grouting of, primarily, the intercolumn joints. These joints present a broken outline in section whose short segments are oriented predominantly normal to the lines of principal stresses, thus ensuring that the concrete at the joint will be in compression. In the vertical direction, the joints are divided into grouting panels, usually 9 m high. The cement grout is delivered to the panel through a system of encased pipes, mounted on the wooden forms of the block being concreted. The arrangement of a typical grouting panel is shown in Fig. 2. The sealing strips for preventing escape of the grout into adjoining panels and temperature joints are made out of galvanized or black sheet iron.The feeder header of 1.5 and 1 in. diameter and the distributing header of.05in, diameter are nailed to the formwork. The air-escape recess for drawing off air and clarified grout from the plane of the grouting panel is made from the sealing-strip material and is fixed by nailing to battens retained on the formwork of the adjoining concreting block.The disk outlets are fixed to the distributing pipes by clips. After stripping the forms, the distributing pipe is bored out, through the opening of the disk outlet, and the outlet covered by a lid.The grouting system is of the closed type; hence it is impracticable to wash it out after grouting, and consequently it can be used only once. Joint grouting must therefore be carried out when the columns facing the joint are at certain temperatures. In the design, these temperatures were set at 5"C for the bottom 20 m and up to 8"C for the remainder of the dam, based on the condition that the design concrete temperature of the internal zone of the dam during its service period will be 3~ and that the cooling of the concrete, after it is rendered monolithic by grouting, will not cause a deterioration in the stressed state of the dam.
The roundhead buttress dam for the Zeya hydroelectric station has a height of 112 m, crest length of 714 m, and volume of about 2,200,000 m 3 of concrete,Reservoir filling began in Aug. 1975 and the first unit was put under load in November.The dam is divided lengthwise into 44 sections of three types: fixed gravity and buttress at abutments, single buttress on the spillway part, and double buttress in the powerhouse part.Galleries for grouting and drainage, measuring 3.5x 3.5 m in section, are constructed at the base of the upstream column of the sections.The distance between axes of the galleries is 7.5 m. In the bank sections the grouting gallery is inclined with a stepped invert.The drainage gallery consists of individual horizontal segments.A Lower Paleozoic intrusion of diorites with veins of lamprophyres and porphyrites of Mesozoic Age form the foundation of the dam.The intrusion extends latitudinally as a band 5-6 km wide.The deep Pikan fault, the formation of which affected the preservation of the rock foundation, is the southern boundary of the rock mass.Six systems of tectonic fractures and zones were traced in the foundation pit during documenting of the site.The predominant strike of the fractures is northeast.In the area of the main structures there are 12 tectonic zones with a thickness of more than 0.5 m and in individual cases more than 3 m. The largest tectonic zone of meridional direction cuts across the axis of the dam in the region of spillway section No. 13. The thickness of the shattered and mylonitized rocks in the zone reaches 10-15 m, and the rocks at the contact with the zone are intensely fractured (Fig. i).A second large tectonic zone in the latitudinal direction with a 60-80 ~ dip toward the upper pool is exposed in the channel and flanks (zone No. 1-8).In the channel it passes i0-15 m from the upstream face of the dam and in the flanks cuts across the foundation in the regions of sections 3-6 and 36-40.A tectonic crack up to 0.5 m thick, filled with gouge, is traced along the entire zone.The blocky structure of the rock caused by the joints is mainly within 10-20 cm.The fracture voids ratio in the channel area is within 0.005-0.15% and in the flanks 0.5-1%.The diorite mass, as we see from the permeability profile (Fig. i) obtained by testing boreholes in the first stage of the grout curtain, is characterized mainly by specific water absorption values less than 0.05 liter/min.Zones of increased permeability are generally individual pockets confined to the largest tectonic fractures and extending to a depth of 30-40 m.Individual absorbing zones are found at a depth of 50-60 m, but we can consider that for depths over 60 m the foundation is practically impervious.The grouting and drainage work in the foundation of the dam* called for 36,000 linear meters of grouting and ii,000 linear meters of drain wells.The project included a deep grout curtain made up of two rows of drilled holes (20,700 m), stabilizing grouting in the foundation of the upstream column (8300 m) and grouting of the ...
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