GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 3.2 643 Site investigations. The area of investigation is located it is located near the variant of Palizzi SS 106 Jonica . The survey area is characterized of quaternary deposits, the studied successionwas alternation of sand and silt. These deposits are moregravelly at the base (sand with metamorphic clasts). The presence of these scant cohesive deposits can generate detachments during the excavation of a tunnel. 3D ERT survey. The non-conventional 3D electrode geometry in the survey area consisted of five pro les of length 24 m and distant 6 m each other (Fig.1). Thus, the three-dimensional ERT data were collected on a rectangular grid of 117.5 × 24.0 m 2 . A total of 240 electrode stations (red dots in Fig.1) along five lines, plus two infinite electrodes, were arranged in the field, and 14873 data points were collected using the pole- dipole array with an inter-electrode space of 2.5 m. The latter has been chosen as it is able to give: exploration depth and 3D coverage greater than that provided by symmetric electrode configurations; good signal to noise ratio; multi- channel receiver optimization. The IRIS Syscal Pro multi-channel georesistivimeter with 96 Fig. 2 - View of subsoil portions corresponding to the most resistive ρ value ranges. Fig. 3 - 3D resistivity model of the investigated area.