GNGTS 2019 - Atti del 38° Convegno Nazionale

690 GNGTS 2019 S essione 3.2 element method. For a three – dimensional visualization, software ViewLab3D, that is able to generate both planar and vertical views of resistivity and also high resolution axonometric 3D view, was used. The software provides the data through different sections or 3D volumes correlated with a different colour scale for resistivity and chargeability. To better analyse the presence of metallic object, the resistivity values were analysed separating the whole values into ranges: 23 Ω·m ≤ ρ ≤ 80 Ω·m, that highlights the presence of urban services; 125 Ω·m ≤ ρ ≤ 200 Ω·m and 300 Ω·m ≤ ρ ≤ 900 Ω·m that allow us to hypothesize the existence of fluvioglacial floods, wet sands and conglomerates (as suggests by consulted geological maps). The highest values of these ranges are due to the rail ballast and, thus, to material characterized by high porosity. The fourth range, with 2 Ω·m ≤ ρ ≤ 40 Ω·m, shows the existence of possible water infiltrations in a highly permeable soil. Fig. 2 - An example of overlap between bodies characterized by the highest chargeability values (between 50 and 107 mV/V) and the lowest resistivity values (between 23 and 80 Ω·m); yellow dashed lines: high chargeability anomalies. The superimposition is shown along two different 3D view to better highlight the presence of landmines: a) and b).