Application of traveltime tomography to GPR data: a preliminary laboratory test
by
Maria Barbara Galati
University of Lecce
Coauthors: T. Quarta, L. Nuzzo, M. Fedi, B.Garofalo

GPR transmission tomography is not yet diffused in the maintenance of Cultural Heritage and civil engineering. However, it could be a viable tool for the diagnosis of internal defects in masonry, either originated at the building stage, or developed subsequently because of normal decay or the occurrence of natural disasters (earthquakes, landslides). The present work shows the preliminary results of a controlled experiment of 2D GPR transmission tomography, performed on a calcarenitic stone block with an empty central hole, using two high-frequency antennas (1000 MHz as transmitter and 1800 MHz as receiver).

In 2D GPR tomography the objective is to get information on the distribution of the model parameters (dielectric constant) on a section of the investigated medium from the minimum traveltimes between sources and receivers. As known, this is an ill-posed inverse problem whose solution is not unique. The reliability of the solution depends on: the acquisition geometry, the data processing and the inversion algorithms used. The elaboration and the inversion of the experimental data using a SIRT algorithm suggest that: 1) the result of the inversion is not strongly dependent on the assumed initial model; 2) the use of smaller cells can increase the resolution; 3) the angular ray coverage plays a fundamental role for a good reconstruction of the non-homogeneities; 4) a very delicate operation is the correct picking of first arrivals, because of noise in the data.

At present, the use of GPR tomography is advisable for the individualization of large non-homogeneities in masonry of historical or modern buildings, and the results are complementary to those that can be drawn by the traditional employment of GPR in reflection mode.

Date received: July 20, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caon-19.