GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 Applications of ground penetrating radar (GPR) in Ponte Vecchio deck monitoring and assessment S. Candela, F. Mittiga, A. Battiato, D. Fiore SOCOTEC Italia S.r.l., Lainate (Milano), Italia Abstract Civil constructions are susceptible to deterioration over time and it’s crucial to continually assess the structural integrity to extend their life. Non-destructive testing is one of the most important tool for this purpose. In recent years there has been a great interest in non-destructive testing, to assess the state of structure without causing any damage that is a very important scope in cultural heritage assessment. There are many non-destructive techniques and the one that have gained prominence during these last few years is Georadar or ground penetrating radar (GPR) (Scotta et al., 2003, Soldovieri et al., 2006). The aim of this report is to show the use of ground penetrating radar as a non-destructive technique for preliminary screening of Ponte Vecchio in Florence (Fig.1) focused for a conservative and structural restauration. It is first important restauration planned in a modern way. The case study reports on the applications of GPR out on the Ponte Vecchio in Florence, with the main objective of identifying possible structural defects and mapping of buried utilities (Fig.2) to give some correct input for the restauration project. 1. Survey methodology GPR is a non-destructive technique that emits a short pulse of electromagnetic energy, which is radiated into the subsurface. When this pulse strikes an interface between layers of materials with different electrical properties, part of the wave reflects back, and the remaining energy continues to the next interface. GPR evaluates the reflection of electromagnetic waves at the interface between two different dielectric materials. The penetration of the waves into the subsurface is a function of the media relative dielectric constants ( ε ). If a material is dielectrically homogeneous, then the wave reflections will indicate a single thick layer. A GPR system is made up of two main components: 1) Control unit 2) Antenna. The control unit contains the electronics, which triggers the pulse of radar energy that the antenna sends into the ground. It also has a built-in computer and hard disk/solid state memory to store data for examination after fieldwork. The antenna receives the electrical pulse produced by the control unit, amplifies it and transmits it into the ground or other medium at a particular frequency. Antenna frequency is one major factor in depth penetration. The higher the frequency of the antenna, the shallower into the ground it will penetrate. A higher frequency antenna will also “see” smaller targets. Many