A Potential Mitigation Measure for the Seismic Distress of the Circuit Wall at the Acropolis of Athens

The seismic design of new retaining structures is usually performed following modern seismic norms. Nonetheless, there are various monumental retaining structures (e.g., fortifications) with high seismic vulnerability, which must be protected against earthquakes, while there exist several limitations on the type of mitigation measures that can be applied to such cultural heritage structures. The present study investigates numerically the seismic response and distress of the Circuit Wall of the Athenian Acropolis. The Wall is a monumental masonry retaining structure surrounding the world-class archeological monuments of the hill of the Acropolis. Given the fact that the wider region of Athens is characterized by moderate seismicity, it is necessary to protect the Wall from strong ground motions. For this purpose, the geological, seismological, and topographic conditions of the Acropolis hill, as well as the geometry and the mechanical properties of the Wall, are realistically taken into account. A realistic finite-element model has been developed for a critical section of the Wall, which has been validated with available records from accelerometers being installed on the Wall. Subsequently, an efficient and suitable—according to international monument restoration guidelines—seismic mitigation measure is proposed. The results of dynamic earth-pressure distribution on the Wall are presented before and after the application of expanded polystyrene (EPS) blocks behind the Wall. Α detailed parametric study illustrates a substantial reduction of dynamic pressures on the Wall when the EPS blocks are applied, either along the entire height or only at the lower part of the Wall.