GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 3.2 641 of concrete structures. However, the comparison and integration of the two techniques have anyway demonstrated the capability and the effectiveness of the adopted techniques to investigate reinforced concrete structures and phenomena occurring during the phase of hardness. Engineering Geophysics represents a valid support to characterize RC structures. Among the various type of techniques, electric and electromagnetic methods can give a optimal contribute for identifying defects and degradation phenomena without interrupt building operability. In the investigated cases, real and laboratory case studies, the integration of GPR and ERT have effectively provided to monitor buildings affected by settlement phenomena. As regarding real cases, presence of high conductive and highly e-m energy attenuating zones have confirmed the presence of not compacted areas and not operating drainage systems. Further, the laboratory experiences have unequivocally showed the great possibilities to analyse RC structures with resistivity methods. In the future corrosion induced artificially thanks to the use of electric generator will be analysed with use of GPR and ERTs supported by other resistivity techniques able to describe physical variation due to decay phenomena. References [1] XXV RAPPORTO CONGIUNTURALE E PREVISIONALE CRESME, Lo stato del territorio italiano -insediamento e rischio sismico e idrogeologico per gli anni 2012-2013-2014 Annan A P (2005), Ground-Penetrating Radar. Near-Surface Geophysics: pp. 357-438. Eisbn: 978-1-56080-171-9 print ISBN: 978-1-56080-130-6 https://doi.org/10.1190/1.9781560801719.ch11 Apostolopoulos, C.A., S. Demis, V.G. Papadakis Chloride-induced corrosion of steel reinforcement – mechanical performance and pit depth analysis Constr. Build. Mater., 38 (2013), pp. 139-146 Breysse D. (ed.), Non-Destructive Assessment of Concrete Structures: Reliability and Limits of Single and Combined Techniques, RILEM State-of-the-Art Reports, DOI 10.1007/978-94-007-2736-6_1, © RILEM 2012 CapozzoliL,RizzoE,CombinedNDTtechniquesincivilengineeringapplications:Laboratoryandrealtest,Construction and Building Materials, Volume 154, 15 November 2017, https://doi.org/10.1016/j.conbuildmat.2017.07.147 deGroot-Hedlin, C. and Constable, S. (1990), Occams’ inversion to generate smooth, two-dimensional models from magnetotelluric data, Geophysics, Vol. 55, No. 12, p. 1613-1624. HIGH-RESOLUTION GEOELECTRICAL CHARACTERIZATION OF THE CONDITIONS OF THE COVERAGE OVERLYING A TUNNEL BEING EXCAVATED BY A NEW 3D DATA ACQUISITION TECHNIQUE C. De Paola 1,2 , S. Candela 2 1 Università degli studi di Napoli Federico II, Napoli, Italy 2  DIMMS Control S.r.l., Vimodrone (Milano), Italy Abstract. The electrical resistivity tomography (ERT) is a method designed to measure the distribution of apparent electrical resistivities in the subsoil by means of a great number of observations, with the aim of determining an image of the underground geological/anthropic structures in terms of true resistivity values retrieved by the inversion of the acquired data. Such technique can be carried out to define 2D, 2.5D or 3D models of the subsurface (e.g., Drahor et al., 2007; Chambers et al. , 2011; Di Maio and Piegari, 2012; Di Maio et al. , 2016). However, dense electrode arrays are required to assure high-resolution (HR) 3D images easily readable by users. For a 3D ERT, usually, the electrodes are placed in a square or rectangular grid keeping the distance between adjacent electrodes constant in the x and y directions. Another common electrode configuration consists of a series of parallel lines whose inter-space must be smaller or equal to two times the electrode separation. These electrode dispositions are difficult to