Design and evaluation of restoration strategies for a fractured ancient stone stele (618–907 CE): Experimental characterization, numerical simulation and theoretical analysis

The rational and non-destructive design of restoration strategies for large and precious stone artworks remains a great challenge worldwide. To study the restoration of a severely fractured ancient stone stele, experimental characterization of the physicochemical and mechanical properties, numerical and theoretical analyses of virtually restored models were conducted. In the study, five different restoration methods were proposed, combining epoxy adhesive with various types of pin materials. Based on the experimental characterization, the basic parameters for model creation were obtained. Through the in-depth analysis of the simulation results (e.g., the first principal stress, displacement and the Rankine safety factor), the most effective method was identified, i.e., a PTFE pin coated with epoxy adhesive applied to the central fracture, with the epoxy adhesive also applied to the fractured surface. Results also reveal that epoxy adhesive applied to the fracture effectively enhances the load-bearing capacity of the stele, achieving the fundamental aim of the restoration practice. The pin can restrict the displacement and reduce the deformation of the entire structure effectively. Under the transversal loads of 4000 N/m 2 applied to the rear surface (L y ) of the stele and of 16000 N/m 2 applied to the right surface (L x ) of the stele, the maximum displacement of the models with the pin and adhesive applied was only 16 % of the model without pin application. Whereas the pin also induces localized stress concentration. Furthermore, coating the pin with adhesive materials can both moderately improve the load-bearing capacity and reduce the deformation of the model. This study facilitates the non-destructive design of repair strategies for stone-built heritage, and also broadens the advanced application of material sciences, engineering mechanics in heritage conservation. • The rational design and evaluation of the restoration strategy were achieved in a non-destructive and repeatable way. • The physicochemical and mechanical properties of the stele were characterized, enabling high-precision model creation. • Combining adhesives and pins, five distinct strategies were proposed and assessed numerically and theoretically. • The adhesives enhance the load-bearing effect, while the pin restricts the displacement and induces stress concentration. • Theoretical and methodological references for the restoration practice are provided.