Grout curtain in the foundation of the earth dam of the Maina hydroelectric station: Fid-Bau Portal

Grout curtain in the foundation of the earth dam of the Maina hydroelectric station

Zhurkina, N. N.

Conclusions 1. The grout curtain was made under conditions of a head on the damp up to 12.5 m under the protection of a temporary blanket placed on natural alluvium; the blanket reduced the gradients of the head in the zone of grouting and provided normal conditions of conducting it. 2. The combined method of grouting used made it possible to save materials and reduce the estimated cost of the curtain by 30%. The use of the packerless method of grouting can be recommended for barrier rows of the curtain when the initial permeability of the soil is greater than 100 m/day in combination with the packer method of grouting of the central rows. The results of control tests showed a high density of the grout curtain (permeability coefficient within limits up to 0.5–1.0 m/day). 3. The new “moving pipe” method proposed by Soyuzgidrospetsstroi together with Gidrospetsproek and tested at the Maina hydrostation showed results close to packer grouting and, as a consequence of this, the possibility of its use. But, with consideration of the insufficient volume of works performed by the moving pipe method (2% of the total amount of grouting), its further testing at other objects is recommended. 4. The design of the packer strings with rubber packers flush with the pipe surface provides tightness and cleanness of the string and is recommended for further use. 5. Grouting experience confirmed the expediency of placing a concrete covering at the site of the works, crated by the separate concreting method.