In the Azerbaidzhan SSR the Sarsang da m was constructed on the Terter River to create a reservoir with a usable storage of 500 million m s. In addition to the dam the hydrodevelopment has a 3.2-m-diameter, 386-m-long diversion tunnel, tunnel-type emergency spillway, and powerhouse with two units [I]. The 430-m-long temporary diversion tunnel located in the right flank was closed with a concrete plug at the time of filling the reservoir and its downstream part was used as a drainage tunnel.With respect to the head (113 m) the dam is one of the largest rolled-fill earth dams in our country, It was constructed from floodplain gravel-pebble soils; the core was made of silty lake-rlver loams compacted by tramping and by rollers to a density of 1.6 g/cm s. A mixture of loam with grus was used above the 670-m mark [2]. The ratio of the width of the core tO the height is about 0.5, which characterizes the core profile as rather economical.The dam foundation consists of a Middle Jurassic volcanic-sedimentary rock stratum represented by porphyrites, tuff breccia, and tuffaceous sandstones. Their characteristic feature is the absence of well-defined bedding and a massive structure.Geostructurally, the construction site is a part of the limb of a large anticline whose crest is located 2-2.5 km to the south. Within the site the rocks are practically monoclinal with a dip toward the right bank and lower pool at angles from 45 to 80 e. Folding processes under rlgld-rock conditions resulted in numerous fractures. The right flank of the structure is located in the zone of a larg e thrust fault.During excavation of the foundation pi t about 150 fractures and zones with openings of more than 10 mm of both tectonic and erosional origin were recorded. A considerable number of the tectonic fractures lle in a direction coinciding with the direction of the beds. Their openings reach 500 mm and more (Fig. I), the filler is represented by compact nonpiping clays and poorly soluble varieties of calcite. The presence of fine feather Jointing determines permeability along the fractures, whereas in the direction normal to the strike they serve as a natural waterproof obstacle. Unfortunately, problems of seepage anlsotropy were not studied sufficiently during the surveys.Fractures of erosional origin and traces of the activity of surface agents extend to a depth of 20-30 m in the mass and even to a depth of 60-80 m in the right flank in the form of a deep erosion pocket. The widths of the weathering cracks near the surface reach 300-350 mm, but rapidly decrease with depth; the filler is loam-clay with grus. Along with the weathering cracks and tectonic fractures the rocks are broken by a network of joints. In the mass they are closed and are of limited extent~ but on removing the overburden, under the effect of the seismic action of explosions and under the pressure of water injected into boreholes they open easily, revealing the blocky structure of the rocks. The average value of the fracture void radio is 4-6%. The static modulus of deforma...

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 ...