GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 ● Following the first phase, the GPR investigation consisted of 3 transversal lines (TID) carried out on the intrados of prefabricated segments, along the entire length of the segments, at pre-established distances starting from the thrust side of the segments and equal to: 0.4, 0.7, 1.3 m (Fig.1c, d). ● After the acquisition, the calibration is carried out for each set of segments investigated. The TID are displayed in real time on the screen connected to the antenna and saved in the system's hard memory. The GPR data, acquired on two-dimensional sections, were processed using a special dedicated software. ● The correct data processing is a fundamental step in order to obtain data can be interpreted in a unique way. It aims to denoise and correct the horizontal and vertical scales of the raw GPR data through a series of filters: o Move start time: used to calculate the zero point and delete the signal portion between air and investigated medium; o Background removal: used to remove continue components along the horizontal direction of the radargram; o Linear gain and time dependant gain: used to amplify the different signal components at different depths to compensate for signal dispersion at the greatest depths; o Vertical and horizontal filtering: applied with the aim of highlighting the answers of the signals visible in the radargram.