GNGTS 2018 - 37° Convegno Nazionale

640 GNGTS 2018 S essione 3.2 ground and enhance the quality of measured data, the holes are also filled with a electrically conductive solution composed by clay (i.e. bentonite) and water. GPR radargrams were acquired near to the façade panels with a SIR3000 (GSSI Instrument) coupled to survey wheel and 400 MHz antenna. Moreover, the uncertainties related to the geophysical data interpretation has pressured to reconstruct real elements of civil engineering RC structures to evaluate, in laboratory conditions the possibilities offered by GPR and ERT to reconstruct the behaviour of RC elements. With these purposes, two RC panels of limited size (1x1m) and a common RC structure composed by columns and beams with foundations (fig. 2) are realized and investigated with geophysical approach. A georesistivimenter Syscal Pro (IRIS-Instruments) connected to self-made cables was used to monitor RC structures and support GPR information acquired with antennas operating at different frequencies. The resistivity data measured in field are inverted with ERTlab and Zondres software while GPR data are processed with Reflex-w. Different types of electrode systems are used to minimize the invasiveness of the method and the results obtained have demonstrated a good capability of ERT for reconstructing engineering structures and supporting GPR results. Fig. 2 - Laboratory tests investigated with a dense grid of resistivity measurements (a): a picture of the steel mesh used for reinforcement of the panel (b), where GPR and ERT measurements are achieved (c); finally the real scale RC structure realized at the Hydrogeosite IMAA-CNR Laboratory (d). Conclusions. For the real cases analysed, results have identified some geophysical anomalies due to discontinuities of the subsoil or a different water content of the subsoil able to generate displacement for foundation structures or not structural elements. The results obtained in laboratory experiences have showed the difficulties for the reading and interpretation of geophysical results, inherent to the electrical and electromagnetic complexity of the behaviour