Engineering-Geological Estimation of Unstable Massif Downstream from the Chirkey Hydropower Station

Abstract

Nine potentially unstable massifs and rockfall prone sites that could fail partially or completely have been identified downstream from the Chirkey hydropower station in 1980. Four areas in the immediate vicinity from the dam have been anchored, and permanent monitoring of the rest is carried out. An inspection of unstable massif about 400 m thick located 1.1 km downstream from the Chirkey dam on the right bank of the Sulak Canyon has been performed. Shear deformations of some blocks of this massif develop progressively and fresh fissures and slides are observed as several sites. The landslide – rockfall phenomena develop on the steep valley slope composed of fractured rocks (limestone and marl) subjected to unloading and seismic shaking typical of the study area. Slope stability was calculated based on field structural-geological and geophysical investigations and drilling, and the appropriate monitoring system was proposed.