Uluslararası Katılımlı IV. Ulusal Baraj Güvenliği Sempozyumu, Elazığ, Türkiye, 9 - 11 Ekim 2014, ss.151-159
The rapid drawdown condition is a critical limit state for many dams, levees, and natural slopes along waterways. This condition occurs when the water level adjacent to a slope drops rapidly relative to the time required for water pressures to dissipate in the slope. As the water level falls, the total stresses in the slope are reduced, and the soil is in a state of undrained unloading. At the same time, the stabilizing effect of the water at the slope surface is removed, and shear stresses increase. Unloading from drawdown will cause a decrease in pore pressures within the embankment. At the same time, the increase in shear stress may either raise or lower pore pressures. These pore pressure responses are stress dependent and are difficult to accurately predict. Since the soil’s shear strength is directly related to the pore pressure, the appropriate strengths for rapid drawdown are hard to evaluate. This paper presents an investigation of a dam slope stability during rapid drawdown. For this purpose, a coupled transient seepage and deformation analyses (including consolidation), together with the stability analysis, were performed using numerical analyses for submerged slopes. Nonlinear elasto-plastic behavior of the slope soil is taken into account while analysis of the generation and dissipation of pore pressure is carried out.