The Engineering Approach to Conservation of Massive Archaeological Structures in Seismic Areas: The Apollo Nymphaeum in Hierapolis of Phrygia

The safety conditions of archaeological remains in seismic areas are strongly jeopardised by a lack of structural completeness, which may trigger dynamic responses among parts and led to partial or overall collapses. However, some of those structures maintain their massive behaviour, which makes the dynamic characterisation difficult for possible predictive analyses. It is the case of the Nymphaeum of Apollo in Hierapolis of Phrygia (Turkey), an impressive stone block masonry structure of the 3rd c. CE, which lies over an active fault. The incomplete structural conditions and the presence of multi-leaf cross sections make this case study of great interest to verifying the reliability of using numerical models for assessment. The discrete element approach was applied to perform nonlinear dynamic analyses under increasing levels of seismicity. The numerical model was based on: i) the detailed shaping of blocks texture, and ii) the onsite inspections and non-destructive testing. Data was also implemented into the numerical model to perform sensitivity analyses. Results showed that the engineering approach proposed herein is able to overcome the challenges imposed by such a massive archaeological structure, facing the unknowns left over by experimental investigations with the opportunity offered by numerical methods such as discrete element modelling.