Sequential Seismic Loading Effects on Earth Dams in Centrifuge Modelling

In seismically active regions, understanding how existing earth dams respond to earthquakes is essential for developing effective rehabilitation strategies and ensuring their safety. Since well-documented case studies are limited, small-scale physical modelling in a geotechnical centrifuge is a key tool for studying their complex seismic behaviour. Such experiments, however, require compromises: the limited number and duration of tests make it necessary to maximise the information obtained from each one. In particular, within a performance-based framework, it is often of interest to examine dam responses to progressively stronger seismic inputs. In centrifuge modelling, this is typically done by applying ground motions of increasing intensity at defined time intervals. This study presents numerical analyses investigating the effects of sequential seismic loading. A PLAXIS 2D finite element model of a small zoned earth dam was calibrated against centrifuge test data. After simulating the impoundment phase, four seismic inputs of increasing intensity were applied sequentially to reproduce the experimental procedure, and then individually to allow comparison. The results show that applying seismic motions sequentially influences the dam’s response through soil nonlinearity and the accumulation of excess pore water pressure. These findings offer useful insights for the design and interpretation of centrifuge experiments on the seismic behaviour of earth dams and similar geotechnical structures.