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Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy
5 results
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- PublicationOpen AccessNew developments in ground probing radar: the possibility of reconstructing a holographic image of underground reflectivity(2000-12)
; ; ;Giubbolini, L.; IRITI, CNR, c/o Politecnico di Torino, Italy ;Sambuelli, L.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy; During the last decade GPR has developed rapidly: instruments have become more compact and more digital, the field of application has broadened from non-destructive testing to humanitarian demining. Studies have been carried out to analyse the full information content of the backscattered wavefield trying to go beyond the time and amplitude analysis. In recent years, many researchers have focused on the possibility of applying holographic acquisition and processing to GPR data. This paper proposes a theoretical outline of a holographic acquisition and processing techniques; a block diagram of the proposed holographic radar; the outlines of the design and the realisation of a custom-built full-scale test-site and the results of the first simulations carried out with newly developed software. The basic rules for an optimum choice of the main acquisition parameters are also given together with a discussion of the main advantages and disadvantages of the proposed techniques.151 417 - PublicationOpen AccessAn experiment of spectral induced polarization(1994-11)
; ; ; ; ; ; ;Balia, B.; Dipartimento di Ingegneria del Territorio, Università di Cagliari, Italy ;Deidda, G. P.; Dipartimento di Ingegneria del Territorio, Università di Cagliari, Italy ;Godio, A.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Ranieri, G.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Sambuelli, L.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Santarato, G.; Istituto di Mineralogia, Università di Ferrara, Italy; ; ; ; ; A Spectral Induced Polarization (SIP) survey was carried out in a mining test site in Sardinia (Italy). Measurements were developed along a profile by using an axial dipole-dipole array with 10 AB positions and 6 MN positions for cach AB. The amplitude and phase spectra of the apparent resistivity were acquired in the 0.25-4096 Hz frequeney range. The results obtained through the processing and inversion step seem to confirm that, with respect to the classical TD/FD Induced Polarization, SIP allows better discrimination of some important characteristics of mineral deposits such as mineral content and grain size.181 303 - PublicationOpen AccessA geophysical study of a coastal plane in Sardinia(1996-01)
; ; ; ;Ranieri, G.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Ferrero, L.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Godio, A.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy; ; The paper deals with some aspects of the planning and the interpretation of the IP and resistivity measurements in the San Priamo coastal plane (Sardinia, Italy). The plane presents some hydrogeological problems related to previous flowages and salt water intrusion from the sea. The geophysical results verified the good resolution of the joint elaboration of the IP and the resistivity soundings, in order to delineate some hydrogeological aspects of the San Priamo coastal plane. In particular, the technique was suitable for detecting salt water intrusion in a fresh acquifer, with good reliability.149 1155 - PublicationOpen AccessMagnetic data interpretation in an industrial waste landfill(2000-04)
; ;Godio, A.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, ItalyA magnetic and an electromagnetic survey using low induction equipment were performed on a test site in an industrial landfill; the main goal of the geophysical survey was to check the reliability of data processing techniques for detecting iron masses inside the upper part of the landfill. Physical and chemical characterisations of the test area, performed on some samples, supplied the geophysical investigations. This paper outlines the data processing of the magnetic data, which was mainly based on the solution of Euler’s equation to detect near surface magnetic sources, associated with iron concentrations. The results of the magnetic survey delineate the existence of high concentration of ferro-metallic objects; the magnetic behaviour of the waste disposal is affected by the presence both of fine iron materials disseminated in sandy and clayey materials, derived from the cast iron foundry industrial process, and ferro-metallic objects such as drums or parts of heavy machines. Some trenches, excavated in the test area, proved that the magnetic behaviour of the landfill is mainly caused by the high concentration of fine iron materials disseminated in the waste. Therefore, magnetic surveys could be useful tools for detecting zones of high concentrations of iron particles in the landfill; this material can be recovered from the landfill and recycled.168 878 - PublicationOpen AccessNotes on fk analysis of surface waves(2000-12)
; ; ; ; ;Foti, S.; Dipartimento di Ingegneria Strutturale e Geotecnica, Politecnico di Torino, Italy ;Lancellotta, R.; Dipartimento di Ingegneria Strutturale e Geotecnica, Politecnico di Torino, Italy ;Sambuelli, L.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy ;Socco, L. V.; Dipartimento di Georisorse e Territorio, Politecnico di Torino, Italy; ; ; The dispersive nature of Rayleigh waves is the basis of many identification procedures to infer the site stiffness profile from surface measurements. This article presents some important aspects related to fk analysis of seismic gathers, which is one of the procedures commonly used to obtain the experimental dispersion curve, focusing on the great influence that the scale of the survey has in the global process. At a short distance from the source, the seismic signal contains information related to different modes of propagation in a composite form. As the wave travels away, the different modal group velocities produce a separation of such information. Hence only if the testing array is sufficiently long is it possible to assume mode separation and to invert the dispersion curve for modal velocities. Otherwise the effects of mode superposition need to be carefully accounted for. To clarify this concept, the results of some numerical simulations are reported, together with some experimental results.279 1463