PSI - Issue 84

Ilaria Catapano et al. / Procedia Structural Integrity 84 (2026) 119–126

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configuration with two boreholes, and the third row presents the combined configuration involving two boreholes and two surface ERT. Larger red points indicate electrode positions, whereas the colored points distributed along the sections represent the theoretical locations of the measurement points. The synthetic models for CS1 are shown in the central and right panels of Fig. 2 and demonstrate that the foundation is detectable in all cases. The central panels show that resistivity ranges from 1 to 500 Ω∙m for scenario (a), while the right panels show that it ranges from 1 to more than 1100 Ω∙m for scenario (b). However, only the SB 2 configuration accurately resolves the geometry and sizes of the structures. As expected, the best results are obtained in scenario (b), where a strong contrast exists between the structure and the surrounding medium (right panels) (Fig. 2).

Fig. 2. ERT results referred to a masonry plinth foundation (CS1): measurement configuration - left; resistivity map for scenario (a) - central , resistivity map for scenario (b) - right.

Fig. 3 shows the synthetic models for the RC footing foundation on RC piles. The electrical resistivity values range between 1 and 100 Ω∙m and 1 and 1900 Ω∙m for scenarios (a) and (b), respectively. As expected, surface acquisitions alone are insufficient to identify the piles due to limited resolution, whereas the use of boreholes significantly improves interpretability. The combined surface-borehole configurations yield the most accurate reconstructions. Furthermore, the greater geophysical contrast in case (b), see right panels, enhances the detectability of the piles, which produce a single and distinct conductive anomaly. However, the two piles cannot be identified separately due to the limited resolution of the technique (electrode spacing of 1 m).