GNGTS 2019 - Atti del 38° Convegno Nazionale

646 GNGTS 2019 S essione 3.2 Fig. 1 - CHERTs performed during the second phase (SC-1). placed in a not homogenous soil while the second one (S-2) is a square masonry panel reinforced with four rebar. As regarding S-1 (Fig.1) the main target is the characterization of the foundation geometry. In this phase, GPR and ERT surface acquisitions are made with use of different antenna frequencies (400 and 900 MHz) in tandem with 3D-ERT performed with flat electrodes realized ad hoc . Then, a time lapse monitoring is tested with the use of only CHERTs performed using three different boreholes placed near the foundation until the depth of 150 cm. The acquisitions are carried out in “steady conditions” (phase 1); then, a tracer test is realized with the introduction of conductive solution in the subsoil (phase 2) and finally, after the polyurethane resin insertion in holes opened near the structure (phase 3), the measurements are repeated. A dataset of over 500 measurements is recorded for each phase and compared with the previous acquisitions in order to distinguish the behaviour of the subsoil in the different contexts. During these phases, GPR measurements on the surfaces are collected according to a dense and regular grid aimed to investigate the variations due to the presence of conductive and resistive solutions and substances injected in the subsoil for the experiments. The second test (Fig. 2) is performed on the masonry panel is performed to analyse the capability of ERT and GPR to monitor the behaviour of the concrete during its curing process. Several acquisitions with electrodes fixed in place and GPR high frequency acquisitions have Fig. 2 - SC2 - RC masonry panel analysed in time-lapse for the monitoring of the curing concrete phenomenon: a) acquisition phase, b) 3D-ERT at the final stage of the concrete curing process.