Characteristics of dams constructed with moraine soils at the hydroelectric developments of the Kovda cascade

Conclusions

The construction of 19 reservoirs with moraine soil under different geological conditions and with soils having different compositions has contributed to knowledge in hydraulic engineering practice, by making possible the development of the following design and construction techniques.

• 1. Moraine soil low in fine particles (30–35%) was successfully used as underlying material for stone protections.

• 2. Moraine soil high in content of boulders (40% and higher) was used instead of riprap on the upstream slopes; a boulder shield was formed after the fine particles were washed out by wave action. The thickness of the moraine layer placed was about 1 m.

• 3. New methods for placement of moraine fill in the pond-forming dikes were developed (dumping over previous deposits); the soil was pushed into the ponds by a bulldozer, and thus exfoliation of the soil was precluded.

• 4. On the riverbed portions of the dam foundations the boulder mantle was left unremoved, since eventually penetration of moraine soil placed in the water under a head [5], along with clay soil, would occur.

• 5. During construction of the dams, the possibility of placing moraine soil in the water, under winter conditions, became apparent; the beginning of the winter period was defined as corresponding to temperatures of − 3 to − 5°C.

The rationality of the construction methods applied is demonstrated by the successful operation of the structures discussed here over a long period of time (5 to 17 years).