Engineering improvements on special hydrotechnical works connected with power development construction

Abstract

The Soviet successes in hydropower development, when the Soviet people approached the 50th Great October anniversary, are closely related to the achievements in the field of special hydraulic works. These, according to the adopted terminology, consist of a work complex connected with foundation preparation and reinforcement and with providing special requirements for hydraulic structures, such as waterproofing, monolithic firmness, etc.* At the dawn of our hydraulic construction, when the head created by dams did not exceed 20-40 m, it was possible to select sites with the most favorable geologic conditions for construction of hydroelectric stations. Thus, the work of foundation preparation was reduced to the necessity for a correct evaluation of the properties of the layers forming the foundations. Now, when we are designing and constructing dams several hundred meters in height and the stresses in the foundations reach 100 kg/cm z, but the location of hydroplants is determined by economic considerations, thus sometimes placing them under very unfavorable geologic conditions, the special works role in foundation preparation has changed sharply. Often, the construction of a hydropower plant is possible only after performance of large-scale complicated operations for reinforcing and sealing the foundation formations. For example, without proper impervious grout curtains in the valley floor and the abutments, filling of the reservoir would be impossible, due to the intolerable seepage losses, and the stability of the structure would be in doubt. A number of similar events have occurred the world over. Our hydropower construction has not experienced such events so far. This refers to the construction of hydraulic structures for thermoelectric stations and to the construction of reservoirs for irrigation use only, where the dams often reach a height of 40-80 m and more.Grouting can be considered the most important type of special work for reinforcing foundations and providing impervious curtains, which consists of cement and other hardening grout injection into the pores and cracks of rock formations through a network of drill holes. Table 1 shows the amount of grouting performed at hydroplants already constructed as well as at those under construction.

Toward the improvement of the construction work for hydroelectric power plants

“…Experience concerning the construction of hydroelectric plants is systematically presented in the journal "Gidrotekhnicheskoe Stroitel'stvo," and some of the results have been described in synoptic articles [1][2][3][4][5][6][7]. For this reason we examine here only the new problems which pertain to the development of the construction work for power projects, and leave out the aspects relating to general organization of construction and to the preparatory period, which constitute different problems.…”