Seismic Performance of a Bituminous-Faced Rockfill Dam

Assessing the seismic safety of an existing earth dam is much more cumbersome than the design of a new structure since several actions and internal processes might have occurred over time. A detailed knowledge of both dam and foundation soils together with a proper characterization of the embankment response under the actual past static loading history, is a prerequisite before handling the dam seismic assessment through a performance-based approach. The paper describes the analysis procedures developed for analyzing the static and seismic response of a bituminous upstream-faced rockfill dam placed in Sicily (IT). The outcomes of the numerical study, performed through a complete dynamic formulation, are presented and discussed focusing on the embankment settlements at the end of the construction stage and on the seismic performance of the dam under the Collapse Limit State scenario. The paper tries to shed light on the role of a strong heterogeneity (limestone block) detected within the foundation soil to ascertain if its presence, which was completely disregarded during the original design of the dam, is beneficial or detrimental for the dam overall response.