Serapeum temple and the ancient annex daughter library in Alexandria, Egypt: Geotechnical–geophysical investigations and stability analysis under static and seismic conditions

The Serapeum Temple and the ancient annex library in Alexandria, Egypt from the Greek–Roman era, represent cultural heritage of outstanding universal values. They suffer weathering — aging as well as multiple geotechnical and earthquake hazards. A pilot study has been carried out in order (a) to define the pathology and the causes of deterioration and degradation (b) to study the seismic performance of this kind of monuments (c) to assess the global risk due to combined hazards and (d) to define the appropriate retrofitting techniques. In the paper a general outline of the various tests, surveys and analyses is presented, highlighting the most important issues related to the static and seismic stability of the above monuments. A particular feature of Serapeum is the column of Diocletian, founded just above it. per presents the comprehensive field and laboratory surveys and tests undertaken in the site, and the numerical analysis of the monument under static conditions and seismic conditions. The field testing program comprises various geotechnical and geophysical field and laboratory tests aiming to define the physical, mechanical and dynamic properties of the soils and soft rock materials of the site where the monuments is founded. Then an extensive parametric 2D and 3D numerical analyses were performed for the pillar and the Serapeum, subjected to seismic motions having different values of peak ground acceleration PGA and frequency content. Advanced soil and rock elasto-plastic modeling has been used throughout the different phases of the numerical analysis. The seismic analysis combined with the static one allowed us to define the pathology of the monuments and to estimate the ultimate load that they can survive under their present conditions.