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Volume 6, Issue 4
  • ISSN: 1569-4445
  • E-ISSN: 1873-0604

Abstract

ABSTRACT

Even if its use is not widespread in the archaeological community, GPR tomography is a viable tool in the maintenance of Cultural Heritage and for the diagnosis of internal defects in masonry, originating either at the building stage or later because of normal decay or natural disasters. Two‐dimensional GPR traveltime tomography aims to obtain information on the distribution of the dielectric constant on a section of the investigated medium from the picked direct arrival traveltimes between sources and receivers. This paper shows the results of a GPR tomographic experiment on a calcarenitic stone block with an empty central hole, using 1000 MHz as transmitter and 1800 MHz as receiver antennas. The original aims of this work were firstly, to assess the usefulness and limits of very basic tomographic tools, accessible also to the non academic community, in the limited case of locating voids in small‐scale structures (pillars or columns) and secondly, to identify possible pitfalls due to acquisition/ processing procedures or to inadequacy of the inversion algorithm. We examine some problems encountered in data acquisition and we propose a method to estimate the effective bandwidth of antenna pairs of different nominal frequencies and to estimate the zero time correction. The experiment shows that picking the first arrivals is a very delicate operation when the airwaves interfere with the transmitted ones and that using the wrong picked traveltimes in the inversion could lead to inconsistencies or to strong reconstruction artefacts. Finite‐difference numerical modelling is helpful both for identifying the correct arrivals to be picked and for exploring the dependence of the tomographic inversion on cell size, geometry of transmitters and receivers and initial model. The inversion results show a strong dependence on the angular ray coverage. The general improvement observed by increasing the illumination directions confirms the opportunity of using, whenever all sides are accessible, as in the case of columns or pillars, both parallel and orthogonal antenna positioning. In the presence of strong velocity gradients, as in this case, even using the best acquisition configuration for transmitters and receivers, the straight‐ray tomography based on the SIRT algorithm can only detect the anomaly but is unable to resolve adequately its geometry and dielectric constant. Although more time‐demanding, curved‐ray tomography or more sophisticated algorithms are therefore necessary for a better characterization of internal defects in most problems of structural assessment.

© European Association of Geoscientists and Engineers © 2008 European Association of Geoscientists and Engineers
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2008-03-01
2024-04-19

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References

  1. AnnanA.P., DavisJ.L. and GendzwillD.1988. Radar sounding in potash mines, Saskatchewan, Canada. Geophysics53, 1556–1564.
     [Google Scholar]
  2. BöhmG. and VesnaverA.L.1999. In quest of the grid. Geophysics64, 1116–1125.
     [Google Scholar]
  3. CardarelliE.2000. Seismic transmission tomography: Determination of the elastic properties of building structures (some examples). Annali di Geofisica43, 1075–1089.
     [Google Scholar]
  4. CatapanoI., CroccoL., PersicoR., PieracciniM. and SoldovieriF.2006. Linear and nonlinear microwave tomography approaches for subsurface prospecting: Validation on real data. IEEE Antennas and Wireless Propagation Letters5, 49–53.
     [Google Scholar]
  5. CervenyV. and SoaresJ.E.P.1992. Fresnel volume ray tracing. Geophysics57, 902–915.
     [Google Scholar]
  6. CroccoL. and SoldovieriF.2003. GPR prospecting in a layered medium via microwave tomography. Annals of Geophysics46, 559–572.
     [Google Scholar]
  7. CroccoL., PriscoG., SoldovieriF. and CassidyN.J.2007. Advanced forward modeling and tomographic inversion for leaking water pipes monitoring. Proceedings of the 4th International Workshop on Advanced Ground Penetrating Radar, IWAGPR 2007, Naples.
     [Google Scholar]
  8. DemingR.W. and DevaneyA.J.1997. Diffraction tomography for multi‐monostatic ground penetrating radar imaging. Inverse Problems13, 29–45.
     [Google Scholar]
  9. DinesK. and LytleJ.R.1979. Computerized Geophysical Tomography. Proceedings of the IEEE67, 1065–1073.
     [Google Scholar]
  10. GalatiM.B., QuartaT., NuzzoL., FediM. and GarofaloB.2004. Application of traveltime tomography to GPR data: A preliminary laboratory test. Proceedings of the First International Conference on Applied Geophysics for Engineering, October 13–15, Messina, Italy.
     [Google Scholar]
  11. GalatiM.B., QuartaT., NuzzoL., FediM. and GarofaloB.2008. Application of traveltime tomography to GPR data: A preliminary laboratory test. Environmental Semeiotics1, 83–93.
     [Google Scholar]
  12. HermanG.T.1980. Image Reconstruction from Projections, the Fundamentals of Computerized Tomography. Academic Press.
     [Google Scholar]
  13. HolligerK., MusilM. and MaurerH.R.2001. Ray‐based amplitude tomography for crosshole georadar data: A numerical assessment. Journal of Applied Geophysics47, 285–298.
     [Google Scholar]
  14. IvanssonS.1987. Crosshole transmission tomography. In: Seismic Tomography with Applications in Global Seismology and Exploration Geophysics (ed. G.Nolet ), pp. 159–188. Reidel Publishing Company.
     [Google Scholar]
  15. JolH.M.1995. Ground‐penetrating radar antennae frequencies and transmitter powers compared for penetration depth, resolution and reflection continuity. Geophysical Prospecting43, 693–709.
     [Google Scholar]
  16. LeucciG., CataldoR. and De NunzioG.2007. Assessment of fractures in some columns inside the crypt of the Cattedrale di Otranto, using integrated geophysical methods. Journal of Archaeological Science34, 222–232.
     [Google Scholar]
  17. LinesL.R., SlawinskiR. and BordingR.P.1999. A recipe for stability of finite‐difference wave equation computations. Geophysics64, 967–969.
     [Google Scholar]
  18. MaurerH. and MusilM.2004. Effects and removal of systematic errors in crosshole georadar attenuation tomography. Journal of Applied Geophysics55, 261–270.
     [Google Scholar]
  19. MenkeW.1989. Geophysical Data Analysis: Discrete Inverse Theory. Academic Press
     [Google Scholar]
  20. NoletG.1987. Seismic Tomography with Applications in Global Seismology and Exploration Geophysics. Reidel Publishing Company.
     [Google Scholar]
  21. NuzzoL. and QuartaT.2007. Metal‐sheet test to estimate shape and frequency content of the radar pulse. IWAGPR 2007 4th International Workshop on Advanced Ground Penetrating Radar, Napoli, Italy, 27–29 June.
     [Google Scholar]
  22. SandmeierK.J.2004. REFLEXW, Version 3.0.8 Windows™ 9x/ NT‐program for the processing of seismic, acoustic or electromagnetic reflection, refraction and transmission data. Copyright 1998–2004 by K. J.Sandmeier , Zipser Straße 1, D‐76227Karlsruhe, Germany. www.sandmeiergeo.de
     [Google Scholar]
  23. SirriS., Eder‐HinterleitnerA., MelicharP. and NeubauerW.2005. Comparison of different GPR systems and antenna configurations at the Roman site Carnuntum. International Conference on Archaeological Prospection, Abstract Volume, Rome.
     [Google Scholar]
  24. SoldovieriF., HugenschmidtJ., PersicoR. and LeoneG.2007. A linear inverse scattering algorithm for realistic GPR applications. Near Surface Geophysics5, 29–41.
     [Google Scholar]
  25. TopczewskiL., FernandesF.M., CruzP.J.S. and LourençoP.B.2007. Practical implications of GPR investigation using 3D data reconstruction and transmission tomography. Journal of Building Appraisal3, 59–76.
     [Google Scholar]
  26. ToppG.C., DavisJ.L. and AnnanA.P.1980. Electromagnetic determination of soil water content: Measurements in coaxial transmission lines. Water Resources Research16, 574–582.
     [Google Scholar]
  27. TrinksI., SinghS.C., ChapmanC.H., BartonP.J., BoschM. and CherrettA.2005. Adaptive traveltime tomography of densely sampled seismic data. Geophysical Journal International160, 925–938.
     [Google Scholar]
  28. TronickeJ., DietrichP. and AppelE.2000. Pre‐processing and quality assessment of crosshole georadar data. Proceedings of the 8th International Conference on GPR, Gold Coast, Australia, 23–26 May.
     [Google Scholar]
  29. TronickeJ., TweetonD.R., DietrichP. and AppelE.2001. Improved crosshole radar tomography by using direct and reflected arrival times. Journal of Applied Geophysics47, 97–105.
     [Google Scholar]
  30. ValleS., ZanziL. and RoccaF.1999. Radar tomography for NDT: Comparison of techniques. Journal of Applied Geophysics41, 259–269.
     [Google Scholar]
  31. VesnaverA. and BöhmG.2000. Staggered or adapted grids for seismic tomography?The Leading Edge9, 944–950.
     [Google Scholar]
  32. WendrichA., TrelaC., KrauseM., MaierhoferC., EffnerU. and WöstmannJ.2006. Location of voids in masonry structures by using radar and ultrasonic traveltime tomography. Proceedings of the 9th European Conference on Non‐Destructive Testing. http://www.ultrasonic.de/article/ecndt2006/doc/Tu.3.2.5.pdf
     [Google Scholar]
  33. WielandtE.1987. On the validity of the ray approximation for interpreting delay times. In: Seismic Tomography with Applications in Global Seismology and Exploration Geophysics. (ed. G.Nolet ), pp. 159–188. Reidel Publishing Company.
     [Google Scholar]
  34. WittenA.J., MolyneuxJ.E. and NyquistJ.E.1994. Ground penetrating radar tomography: Algorithms and case studies. IEEE Transactions on Geoscience and Remote Sensing32, 461–467.
     [Google Scholar]
  35. ZhouC., LiuL. and LaneJ.W.2001. Nonlinear inversion of borehole‐radar tomography data to reconstruct velocity and attenuation distribution in Earth materials. Journal of Applied Geophysics47, 271–284.
     [Google Scholar]
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Potential and pitfalls of GPR traveltime tomography for ancient buildings investigation: experiments on a small‐scalem real and synthetic calcarenitic block
Near Surface Geophysics 6, 207 (2008); https://doi.org/10.3997/1873-0604.2008016
/content/journals/10.3997/1873-0604.2008016
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