A coupled seepage-stability model to analyze the Vajont Reservoir influence

In the present work the 1963 Vajont landslide has been back-analyzed in detail to examine the influence of performed reservoir operations on the Mt. Toc slope stability. Coupledseepage stability analyses show that the main trigger of the Vajont rockslide was the reservoir-induced water table which formed as a consequence of rapid seepage inflow. The permeability of the shear zone material occurring at the base of the Vajont rockslide is evaluated at 5·10 -4 m/s and back-calculated values of the friction angles φ range from 17.5° to 27.0°. Considering mountain reservoirs, slope failures can occur during both filling and drawdown phases. In the Vajont case, due to highly permeable materials of the shear zone, the slope stability decreased during filling and increased during drawdown. Another time-dependent phenomenon of mechanical nature (progressive failure) has to be considered to understand the final slope behaviour related to the last drawdown. © Springer-Verlag Berlin Heidelberg 2013.