| Abstract: | Conclusions | 1. | The mechanical effect of a reservoir extends to a rock mass whose volume exceeds the reservoir volume by two orders. This effect is expressed in the formation of a depression zone in the territory adjacent to the reservoir, “breakdown” of the reservoir walls, and extreme increase of the number of local earthquakes whose hypocenters are located within the indicated volume of the mass. Maximum changes in the stress—strain state of the mass occur at the reservoir filling stage. | | 2. | Stabilization of the reservoir levels causes stress relaxation in the mass within (0.8–-1.9)·108 sec, as a result of which static equilibrium of the mass—reservoir system is reached. Subsequently, surface deformations and stresses in the mass change in accordance with fluctuations of the reservoir water level. The number of local earthquakes decreases relative to the natural level. The intensity of “breakdown” of the walls decreases with rise of the water table. | A substantial change in the design operating regime of the reservoir causes significant changes in the stress—strain state of the mass, which are expressed in an extreme increase of the water table and drainage discharges in the dam foundation, increase of the number of local earthquakes, etc. | 3. | Disturbance of the cause-and-effect relations in the reservoir—mass system can be regarded as a sign of a change in the regional stress field, including as a precursor of regional earthquakes. | Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 42–48, July, 1998. |
