Physical modelling of the dynamic response of a zoned earth dam

In highly seismic countries, the maintenance and restoration of existing earth dams involve assessing their seismic performance to design effective rehabilitation strategies. This is a complex issue, particularly in the case of zoned earth dams, where materials with different hydraulic and mechanical properties interact during both normal operation and extreme conditions. Therefore, understanding the response of zoned earth dams under severe seismic loading is crucial to ensure their safety and resilience. Given the limited availability of well-documented case histories, conducting small-scale physical modelling in a geotechnical centrifuge is essential to highlight the most significant aspects of the behaviour of such complex structures. This paper presents the results of two dynamic centrifuge tests carried out to investigate the seismic response of a zoned earth dam, 13 meters in height and 39 meters in width, at the prototype scale. The upstream and downstream slopes consist of compacted sand, while the core is made of compacted clayey sandy silt. Extensive laboratory testing was performed to determine the geotechnical properties of the soils used in the experiments. During the tests, the model was densely instrumented with pore pressure transducers, tensiometers, accelerometers, and linear and rotational sensors to monitor the displacement field of the dam. Under operational conditions in terms of water level, the dam was subjected to a sequence of dynamic excitations of increasing intensity, while recording the dynamic response of the model by the accelerometers installed in the embankment. The research findings contribute to a broader understanding of the behaviour of this category of earth structures under severe seismic conditions and provide valuable experimental data for the calibration of numerical tools to be used for parametric analyses.