Electrical Resistivity Tomography and Ground Penetrating Radar for Bridges: Preliminary Findings from the EMILI Project

Transportation networks rely heavily on bridges whose safe operation depends on maintaining structural soundness. Natural phenomena, such as landslides and human-induced incidents, pose significant threats to bridges, with consequences ranging from compromised safety to complete failure and service interruption. Multiple variables determine the extent of structural deterioration, including the nature of hazardous events, material composition, and existing maintenance conditions. A comprehensive evaluation of landslide-related threats necessitates examining a variety of factors, including the geophysical properties of the subsoil and an in-depth knowledge of the bridge key structural elements, such as its foundations, piers, and abutments, as well as their current state of conservation.

Supported by the FABRE consortium, the EMILI project - ElectroMagnetic techniques for Investigating Landslide and structural damages due to their Impacts on bridges - aims to establish uniform protocols and operational frameworks for electromagnetic investigation techniques in bridge-landslide hazard evaluation. By targeting Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR), EMILI advances the standardization, reliability, and field implementation of electromagnetic approaches.

Initial findings from EMILI are discussed here, encompassing two primary contributions. The first concerns a comprehensive literature analysis examining both capabilities and constraints of ERT and GPR in field applications involving bridges, landslides, and their interactions. The second deals with preliminary results from simplified numerical models exploring the detection potential of ERT and GPR when applied via conventional and unconventional measurement configurations. Specifically, surface and borehole data from simulated scenarios involving diverse lithologies, foundations, and water content are considered and processed to establish the potential and limitations of ERT and GPR in estimating the shape and depth of the foundation piles.

Preliminary synthetic results are promising and demonstrate the capability of ERT and GPR to identify foundation structures in simplified geological contexts.