The results of dipole sounding of the right bank of the dam of the Chirkei hydroelectric power plant

Abstract

For the first time in the practice of full-scale studies in the area of the Chirkei HPP dam, the method of dipole electric sounding was used. The aim was to study the geodynamic processes in the rock mass located in the sides of the highrise dam to develop new methods of control of natural and man-made hazardous geological processes. The basis for the study of deformation processes in a large volume of the right bank of the dam was laid by the results of electric sounding of rocks by a small four-electrode in-well installation over the period 2010–2015, which showed that the change in the level of the reservoir caused seasonal deformation of rocks. The use of dipole sounding can significantly increase the size of the object under study. The volume of the probed rocks of the right bank of the dam is 6×106 m3, that is 2000 times larger compared to the four-electrode in-well installation. The equipment used is characterized by the continuity and high accuracy of measurements of apparent resistance of the mass, which enables to register the dynamic processes occurring in it. The results of observations by the method of dipole sounding over a short period of 2018 enable to conclude about the anthropogenic impact of the Chirkei hydroelectric power plant on the stress-strain state of rocks adjacent to the right side of the dam. For individual periods of observation, variations of apparent resistivity of large amplitude are detected, suggesting that the analyzed mass is in conditions of unstable equilibrium, i. e. displacements occur from time to time along the cracks in place. The movements can be triggered by starts of hydraulic units. Shifts in large tectonic cracks in the rock mass near the right side of the dam can lead to landslide processes and opening of cracks in the dam contact zone. The method of continuous dipole electric sounding can find its practical application for monitoring of hazardous geological processes in hydroelectric power plants.