Suction-induced effects on the seismic response of a zoned earth dam through simplified dynamic analyses

In zoned earth dams, the contrast in hydraulic conductivity between the core and the shells causes the saturation line to drop across the core, leaving most of the downstream shell in an unsaturated state. Since suction provides for additional stiffness and strength to soil, the paper investigates the contribution of suction-induced effects in the downstream shell and other dam zones located above the saturation line on the seismic response of the dam. To this aim, a Newmark-based approach has been adopted. The seismic response of the dam is first analysed by equivalent linear dynamic analyses to obtain the equivalent acceleration acting throughout the sliding mass, which is then employed in the application of the Newmark method. Since critical surfaces for zoned earth dams are those crossing the core, the study focuses on sliding mechanisms involving these surfaces.