ABSTRACT
Operation of large hydraulic engineering structures such as the Sayano-Shushenskaya HPP (Eastern Siberia) and Inguri HPP (Western Georgia) and other high-pressure hydroelectric power plants causes significant changes in the initial rock properties, that is, the rock properties laid down in the project, as well as changes in the structure of the weakened zone and the discharge zone in comparison with the project. Long-term geophysical monitoring allow observe during significant time intervals, measured in tens of years, the changes in the properties and structure of the enclosing rock massif. Specified impacts are conditioned not only by rock excavation but also by the processes of their operation when due to periodical fluctuations of water level in the reservoir the significant changes of hydrogeological conditions and violent changes of force impacts transferred to the enclosing rock mass occur. At that, different natural and technogenic geodynamic processes development of which may cause hazard phenomena for the structures, such as damage of local parts of the foundation due to large cracks propagation, appearance of the zones of anomalously high seepage, collapse of separate blocks of the rock mass and others, are activated in the surrounding geological environment. Thus, geodynamic processes occurring during construction and operation of high dams result in significant changes of initial engineering and geological structure of enclosing rock mass.
The operation of large hydraulic structures such as Inguri HPP (Georgia), Sayano-Shushenskaya HPP (Eastern Siberia) and other high-head HPPs causes significant changes of initial, i.e. design properties of rock foundations (elastic, strain and strength indices), and changes in the structure of weak zone and zone of de-stressing in comparison with the design. Long-term geophysical investigations at monitoring allow observing the changes in properties of enclosing rock mass during the significant time intervals for the decades under the influence of seasonal fluctuations of the reservoir level and variations of stress-strain state of enclosing mass, water saturation, uplift pressure and factors that activate the modern natural and technogenic geodynamic processes in the near-surface parts of Earth’s crust at dam section, and thereby increase the geodynamic risk in the area of the project.
