Assessment of Variations of Indicators of Elastic and Deformation Properties of Rock Massif in the Reservoir of the Saya
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Vol. 54, No. 4, November, 2020
ASSESSMENT OF VARIATIONS OF INDICATORS OF ELASTIC AND DEFORMATION PROPERTIES OF ROCK MASSIF IN THE RESERVOIR OF THE SAYANO-SHUSHENSKAYA HYDROELECTRIC POWER PLANT WITH DIFFERENT WATER LEVELS E. A. Gorokhova1 Translated from Gidrotekhnichesko Stroitel’stvo, No. 6, June 2020, pp. 22 – 27.
Results of measurements of the velocities of elastic waves in the rock massif of the foundation of the dam of the Sayano-Shushenskaya Hydroelectric Power Plant in the case of minimal and maximal upstream pool levels are presented. A difference between the variations of the velocities of the longitudinal and transverse waves with increasing upstream pool level on the right-bank and left-bank abutments of the dam is established. Keywords: velocity of longitudinal waves (P-waves); velocity of transverse waves (S-waves); variation of properties; seismic tomography sections; decomposition of massif; water level in reservoir.
results of repeated investigations of the same sections of the rock massif in the foundation of the Sayano-Shushenskaya Hydroelectric Power conducted with the use of a complex of uniform methods and measurement instruments over different time intervals and at different levels of the reservoir (different upstream pool levels) from 2011 to 2017. Blocks were identified in the right-bank and the left-bank abutments in the course of investigations of the massif in 2015 on the basis of the spatial distribution of the velocities of the seismic waves, the boundaries of which are the tectonic disturbances. Observations of the variations at different upstream pool levels were performed within each block (Figs. 1 and 2). Studies carried out by means of seismic tomography at the minimal level in the reservoir (upstream pool level = = 501 m, April – May 2017) and at the maximal level (upstream pool level = 538 m, August – September, 2017) were performed in order to assess the contemporary properties and state of the rock massif in the coastal abutments of the dam of the Sayano-Shushenskaya Hydroelectric Power Plant. A comparison of the indicators of the elastic and deformation properties of the massif was performed in three stages, first a comparison of the velocity sections (tomograms) at two water levels in the reservoir; a comparison of the average values of the velocities of the longitudinal and transverse waves; and, finally, identification of possible factors that could be responsible for variations in the elastic properties of the massif.
The results of geophysical, geomechanical, and geological percolation investigations conducted by different specialized organizations since the 1990’s have demonstrated that in the course of functioning of the structure, the rock foundation of the Sayano-Shushenskaya Hydroelectric Power Plant has experienced the effect of different natural and technogenic factors, and as a result of these factors the rock that form the bedrock foundation has undergone substantial changes [1, 3, 5]. Detailed investigations of the foundation and coastal abutments of the dam
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