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Advanced Ground Penetrating Radar (IWAGPR), 2013 7th International Workshop on

Date 2-5 July 2013

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Displaying Results 1 - 25 of 53
  • Full 3-D electromagnetic subsurface imaging using ground penetrating radar

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    This work is concerned with the 3-D imaging problem of buried objects via enhanced microwave tomography ground penetrating radar (GPR) surveys. In particular, we propose a model based imaging approach, which exploits the Born approximation and accounts for the vectorial nature of the scattering phenomenon as well as for the presence of the air-soil interface. Moreover, a truncated singular value decomposition (TSVD) inversion scheme is applied to achieve stable and accurate results. The advantages offered by a full 3-D inversion algorithm with respect to the commonly adopted strategy, which produces 3-D images by interpolating 2-D reconstructions, are assessed against experimental data gathered in laboratory controlled conditions. View full abstract»

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  • A subspace leakage suppression technique for high resolution processing of dispersive GPR signals

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (417 KB) |  | HTML iconHTML  

    Linear prediction methods, based on a Hankel data matrix, suffer from subspace leakage and degraded resolution when applied to data models that do not result in a mode matrix with Vandermonde structure, such as the constant-Q model. In the absence of noise, the Vandermonde structure ensures the equivalence between the number of backscattered signals and the rank of the data matrix. This paper first identifies the origin of subspace leakage residing in linear prediction methods when applied to data of the constant-Q model. Then it proposes a frequency-distortion technique, based on the extension theorems, for suppressing this leakage and preserving the time resolution performance of subspace-based and linear prediction data processing methods. View full abstract»

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  • GPR case histories and known physical principles

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    The physics and technology of ground penetrating radar [GPR] and its ability to detect buried targets are well understood and proven even though the underlying physics and engineering are not simple. Its performance can be predicted with some accuracy given information on the characteristics of the soil and target. Where new developments in GPR can demonstrate proven outcomes within a framework of statistically based evidence and procedures, as well as known science and engineering methodology, then prospective end users can be confident in their use. However, some performance claims that need very careful scrutiny are proposed by certain operators. These claims are usually quickly discounted by the well informed, but appear plausible to the less knowledgeable and it is the aim of this paper to help end-users ask the right questions. The promise of “new” scientific breakthroughs, even where these remain unproven using the normal scientific procedures and in some cases transcend known physics, can mislead those unfamiliar with the proven science and technology underlying GPR. This paper very briefly reviews the fundamental physics of ground penetrating radar and methods of establishing whether or not it will accomplish a given goal. Several examples of claims regarding ground penetrating radar are described as well as the criteria against which new techniques are normally assessed. The paper concludes with a simple check list that could be applied by those about to consider the acquisition or use of ground penetrating services or equipment. View full abstract»

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  • Quantifying GPR transient waveforms in the intermediate zone

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2028 KB) |  | HTML iconHTML  

    In this paper we examine the transient electromagnetic field variation around dipole antennas placed on the surface of a half-space. To achieve this we employ three-dimensional (3D) finite-difference time-domain (FDTD) numerical modelling. We have previously shown how antenna height, shielding and ground properties impact the directionality and energy flow. Here, we report how the transient fields around a dipole change their amplitude, shape and frequency content. Further, we demonstrate how the aforementioned attributes change as we move away from the source. View full abstract»

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  • Singlehole borehole radar measurement with a thin directional borehole radar sonde

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (653 KB) |  | HTML iconHTML  

    This study demonstrates 3-D imaging of a fault using a thin (5.4 cm diameter) directional borehole radar sonde. In order to make the thin sonde, we needed to reduce interference between the centered conducting cylinder (CCC) and the antenna elements in the coaxial-fed circular dipole array in a borehole (CFCAB). Ferrite beads were loaded in the CCC for reduction of the interference. We conducted singlehole measurements with the thin sonde in an air-filled borehole. In this experiment, according to the power spectrum of a direct wave, we found that the ferrite loading decreased the resonant frequency of the CCC, widening the operating frequency bandwidth. The image constructed using the directional borehole radar agrees well with the information obtained from the boring core samples and observations in the gallery. View full abstract»

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  • The Mt. Pollino Fault (southern Apennines, Italy): GPR signature of Holocenic earthquakes in a “silent” area

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1619 KB) |  | HTML iconHTML  

    The Mt. Pollino Fault Zone is located in the northern sector of the Calabria region (southern Italy). It represents a segment between the southernmost part of the Apennines and the Calabrian Arc. In the Pollino area, seismic events of magnitude > 5 are not currently reported in literature and within the seismic catalogues, therefore this “gap” zone has been defined “silent”. Due to the geomorphological, geological and paleoseismological evidences of Quaternary faulting, the Pollino-Castrovillari faults are considered active, as demonstrated also by some recent reactivations, that have generated several earthquakes of moderate magnitude (Mmax ≤ 5.0) in a north-western sector, near Mormanno (Mercure Basin) and Morano villages (Morano-Castrovillari Basin). Therefore, the studied area retains many uncertainties in the definition of the seismic hazard. With these premises an integrated project started in 2012 (Agreement INGV-DPC 2012-2013, Project S1) aims to improve the base-knowledge for assessing the seismogenic potential. Among the different geological studies, the project encompasses the GPR fault imaging on several sites, having different goals: 1) define the location and the geologic characteristics of active faults; 2) detect new evidences of “recent” faulting; 3) correctly locate these structural elements on a geologic map; 4) support further paleoseismological surveys. A first 2DGPR survey was done at the Grotta Carbone site, about 4 kilometers from Castrovillari, for which some trench logs were already available, in order to “image” the fault zone and to provide a GPR data calibration using the stratigraphic information. The results of the radargrams interpretation show a characteristic GPR signature of the tectonic structures and faulted units and a different dielectric behavior among the units located across the fault, revealing an excellent matching with the available geological da- a. Clear tectonic features and their vertical offset between layers have been highlighted within the fault zone. The stratigraphy of the trenches have been extended, along the fault and in depth, providing new useful information essential for a better definition of the seismic hazard of the area and for a future 2D/3D dataset extension across other sites. View full abstract»

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  • Non destructive assessment of Hot Mix Asphalt compaction with a step frequency radar: Case study

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1132 KB) |  | HTML iconHTML  

    A Step Frequency Radar (SFR) is used for assessing the compaction of Hot Mix Asphalt (HMA) layers. The system is composed of a network analyser and an Ultra Wide Band (UWB) antenna placed above the road surface. The measurements are carried out on a new-paved road in Cagny (Normandie, France). The SFR system provides the permittivity of the first overlay. The data is corrected from vehicle vibrations and calibrated at fixed locations. Then, the HMA compaction is deduced with a Lichteneker-Rother (LR) model. The results are compared with standard tests (gamma bench testing on cores and in-place nuclear gauge). We show that the SFR system allows the nondestructive assessment of HMA overlay with a high density of points, and with an accuracy close to the compaction provided by standard tests. View full abstract»

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  • An evaluation of the early-time GPR amplitude technique for electrical conductivity monitoring

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1128 KB) |  | HTML iconHTML  

    In the present paper we use the recently-proposed early-time GPR (Ground Penetrating Radar) amplitude technique with the aim of detecting the variations of electric conductivity in a porous material having a uniform permittivity. A specific laboratory setup has been realised to evaluate the sensitivity of the early-time amplitudes to the variations of the subsurface salt concentration (i.e., conductivity). To assess the capacity of the early-time amplitude to follow the electrical conductivity changes, we compare the early-time results acquired using the envelope of the first part of GPR signals with the concurrent conductivity measured with TDR (Time Domain Reflectometry). The GPR survey has been carried out using a bistatic radar unit (Sensors & Software, Inc) operating at 1 GHz. Further useful information has been derived by suitably implementing a full-wave numerical modelling, able to accurately analyse the features of the waves detected by the GPR with flexible parameterization. Our results indicate that the near-surface electromagnetic properties of the material can be directly extracted from the GPR early-time amplitude technique. In particular, both experimental and numerical data show a very high correlation coefficient between the radar signal amplitude and the TDR-derived electrical conductivities. View full abstract»

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  • Cylindrical-wave approach for line-source electromagnetic scattering by buried dielectric cylinders

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (379 KB) |  | HTML iconHTML  

    An analytical-numerical model for the electromagnetic characterization of GPR scenarios, with a line-source illumination field, is proposed. Solution is given in the spectral-domain, in the case of a two-dimensional geometry with dielectric scatterers buried in a semi-infinite medium. The source and scattered fields are represented by means of cylindrical-wave expansions; the concept of plane-wave spectrum of a cylindrical wave is used to describe the interaction of the fields with the air-soil interface, following the fundamentals of the Cylindrical Wave Approach. The proposed model has been implemented in a Fortran code and numerical results are presented. The electromagnetic field can be calculated both in the near and far region, for arbitrary size and position of the scatterers, and the method can deal with both the fundamental transverse-electric and transverse-magnetic polarization states. View full abstract»

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  • Topographic migration of GPR data with variable velocities

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1460 KB) |  | HTML iconHTML  

    The topographic relief of a typical ground-penetrating radar (GPR) survey can easily be in the range of the target depth. In complex subsurface settings, this requires the application of topographic migration schemes to reliably image subsurface structures. Furthermore, a shallow ground water layer introduces significant vertical variations in GPR propagation velocity, which should be considered during migration to accurately image subsurface structures. In this paper, we present a modified topographic migration scheme, which is able to account for vertical variable velocities by using the root-mean-square (rms) velocity approximation. We evaluate our migration scheme by using synthetic and field data, which represent typical near-surface sedimentary structures often investigated using GPR. These examples demonstrate that a significant improvement in structural imaging quality is achieved by considering rms velocities during topographic migration. View full abstract»

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  • Use of radar in road investigation BRRC experience

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    This paper summarizes the radar experience of the Belgian Road Research Centre (BRRC). The BRRC acquired a radar system (horn antennas of 1 and 2 GHz) in order to investigate the road structure: estimation of layer thickness (improvement of back calculation), visualization of homogeneous zones, detection of road damages, and so on. Some case studies are presented here. The possibilities are described but also the limitations of our equipment. The radar improves the knowledge of the road structure but there are some limitations. We hope some of the limitations will be solved by improving the acquisition parameters (equipment or humidity conditions) and the processing. View full abstract»

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  • Correlation of internal salt structures with GPR amplitudes

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (354 KB) |  | HTML iconHTML  

    In salt deposits with low electric conductivity ground penetrating radar (GPR) is an efficient non destructive tool for the exploration of internal structures. Faulted salt layers, potassium, clay, and anhydrite can be mapped by measuring distance and direction of reflecting objects. Various antenna types help to enhance resolution or penetration depth. Additional information about the conductivity of reflecting structures is included in the attenuation of the direct and reflected signals. Within the last two decades unique results from a salt dome in Northern Germany with various GPR systems were achieved. With this information a classification of various salt structures can be made by studying the signal amplitudes of reflections and of the direct wave between transmitting and receiving antenna, especially with borehole measurements. View full abstract»

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  • GPR characterization of water transfers in Tuffeau walls

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB) |  | HTML iconHTML  

    Rehabilitation of old buildings is a necessity for reductions in energy consumption and preservation of cultural heritage. To achieve good rehabilitations in old buildings, an efficient diagnosis allows to determine the various existing pathologies and their causes. In this study, we focus on the Tuffeau which is widely used in the old buildings of the Loire Valley (France). Currently, the moisture condition measurements are carried out using probes that are placed in the walls. These sensors take very localized measurements with an alteration of the structure (coring). In this paper, we propose to analyze the water gradients due to water transfer in Tuffeau blocks using an electromagnetic waveguide model applied to nondestructive testing (Ground Penetrating Radar). View full abstract»

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  • Temporal monitoring of the soil freeze-thaw cycles over snow-cover land by using off-ground GPR

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (13745 KB) |  | HTML iconHTML  

    We performed off-ground ground-penetrating radar (GPR) measurements over a bare agricultural field to monitor the freeze-thaw cycles over snow-cover. The GPR system consisted of a vector network analyzer combined with an off-ground monostatic horn antenna, thereby setting up an ultra-wideband stepped-frequency continuous-wave radar. Measurements were performed during nine days and the surface of the bare soil was exposed to snow fall, evaporation and precipitation as the GPR antenna was mounted 110 cm above the ground. Soil surface dielectric permittivity was retrieved using an inversion of time-domain GPR data focused on the surface reflection. The GPR forward model used combines a full-waveform solution of Maxwell's equations for three-dimensional wave propagation in planar layered media together with global reflection and transmission functions to account for the antenna and its interactions with the medium. Temperature and permittivity sensors were installed at six depths to monitor the soil dynamics in the top 8 cm depth. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and permittivity data and in particular freeze and thaw events were clearly visible. A good agreement of the trend was observed between the temperature, permittivity and GPR time-lapse data with respect to five freeze-thaw cycles. The GPR-derived permittivity was in good agreement with sensor observations. The proposed method appears to be promising for the real-time mapping and monitoring of the frozen layer at the field scale. View full abstract»

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  • 3D characterization of an aquifer using full-waveform inversion and amplitude analysis

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (691 KB) |  | HTML iconHTML  

    For accurate prediction of flow and contaminant transport in aquifers, a high resolution method is necessary, that is able to detect small-scale high-contrast layers. Such layers can act as low-velocity waveguides in the GPR signal and can be related to a zone of preferential flow or impermeable clay lenses. Here, we characterize a saturated gravel aquifer in 3D by applying 2D full-waveform inversion and an amplitude analysis approach that explores the information content present in the measured GPR data. The full-waveform inversion results of the permittivity and conductivity show decimeter-scale high resolution images and similar results at the borehole crossing and at the intersection of the diagonal planes. In all six planes, a high permittivity layer between 5m-6m depth was resolved, which acted due to the high contrast to the surrounding as a low-velocity waveguide indicating a zone of higher porosity. The amplitude analysis of the measured data showed significant wave propagation for transmitter located in and outside this zone. By using this information, the method was able to detect the waveguide layers and their boundaries in the measured data, which were confirmed by the full-waveform inversion results. Permeability logs indicate a zone of preferential flow between 5m-6m depth, which shows a good agreement with the high permittivity/porosity zone detected by the full-waveform inversion. View full abstract»

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  • Intrinsic modeling of radar antennas: From far-field to near-field conditions

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (185 KB) |  | HTML iconHTML  

    We p resent an intrinsic way for modeling radar antennas operating in near-field conditions for wave propagation in planar layered media. Fundamental antenna features consist of an equivalent set of infinitesimal electric dipoles, field points and associated global reflection and transmission coefficient functions. These antenna characteristic functions permit to describe wave propagation between the radar reference plane and the equivalent source dipoles and field points. Near-field antenna-medium coupling is inherently accounted for and the antenna characteristics do not depend on the medium. We show an example of application in which the dielectric permittivity of a sand subject to a range of water contents is estimated from measurements collected with a vector network analyzer connected to a Vivaldi antenna. A very close agreement between the measurements and the model was obtained and the retrieved permittivities were very well consistent with the corresponding water contents. The proposed method shows great promise for digital soil mapping using ground-penetrating radar (GPR) and non-destructive testing of materials. View full abstract»

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  • 2D full waveform inversion of GPR surface data: Permittivity and conductivity imaging

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (947 KB) |  | HTML iconHTML  

    In this study, we present a frequency-domain full waveform inversion (FWI) algorithm of ground-penetrating radar (GPR) data for the simultaneous reconstruction of the dielectric permittivity and electrical conductivity of the investigated material. The inverse problem is formulated as a quasi-Newton optimization scheme, where the influence of the Hessian is approximated by the L-BFGS-B algorithm. Numerical tests on a cross-shaped benchmark from the literature demonstrate the need for an ad hoc scaling between the relative permittivity εr and a relative conductivity σr through a reference conductivity σo We study the behavior of the inversion with respect to this reference conductivity and to the frequency sampling approach (simultaneous vs. sequential inversion), showing that i) the inversion process should be governed by the permittivity update to respect the natural sensitivity of the cost function and provide a reliable kinematic background soon the early iterations, ii) the value of σo should be tuned to find a compromise between resolution and noise in the final image of conductivity. We apply our scaling approach in a realistic synthetic example, illustrating that the quasi-Newton method based on the L-BFGS-B algorithm is able to reconstruct both permittivity and conductivity from multi-offset data acquired with a surface-to-surface acquisition configuration. View full abstract»

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  • Road inspection using full-wave inversion of far-field ground-penetrating radar data

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    Inspecting how robustly and safely the roads are built in order to develop better methods for both design and quality control of materials is an important task in road engineering. In this research we studied the potential of full-wave model of Lambot et al. 2004 for far-field ground-penetrating radar (GPR) configuration in order to retrieve the physical and electromagnetic properties of the road, including both asphalt and subbase layers. Two different GPR systems, namely, stepped frequency GPR and impulse GPR systems were used to collect data along a 50 m long transect. Accurate positioning was performed using a dGPS and a survey wheel. Both GPR data sets were processed using GPR full-wave inversion in the time domain focusing on the asphalt and subbase reflections. Comparison of the results from both GPR systems showed a good agreement between them. In addition, results showed that a compacted zone on the road leads to a compaction feature influenced the retrieved road parameters. The proposed radar data processing method demonstrated a strong potential of the GPR full-wave model to be used for quantitative road inspection. View full abstract»

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  • Effect of penetration of water under pressure in hardened concrete on GPR signals

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    This paper describes the laboratory experiments carried out to analyze the effect on ground penetrating radar signals of penetration of water under pressure in hardened concrete specimens of different W/C ratio. The survey was conducted by measuring the velocities (the real permittivity) and amplitudes of the waveforms (wave energy level), recorded when the concrete specimens were first saturated, then partially dried and finally injected with pressurized water. The measurements were based on coupling a 1,6 GHz and a 2,6 GHz antennas on the surfaces of concrete specimens. The results showed that all the wave parameters studied were influenced by the presence of water in the specimens and a similar pattern behavior was observed regardless the W/C ratio. This relationship was specially highlighted by the contour maps analysis, since the spatial distribution of the studied wave parameters reproduced the shape of the injected water in the specimens. It is interesting to point out that, when measuring with both antennas after that the specimens were injected with pressurized water, we found that the wave energy level of the direct wave could be a very suitable parameter to study the depth of the water front. View full abstract»

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  • Towards physically-based filtering of the soil surface, antenna and coupling effects from near-field GPR data for improved subsurface imaging

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (427 KB) |  | HTML iconHTML  

    Physically-based filtering of antenna effects in far-field conditions, including antenna-ground interactions, can be performed using intrinsic antenna modeling based on antenna global reflection and transmission coefficients. This has been in particular validated for frequency domain radars for quantitative reconstruction of layered media using full-wave inversion and improved subsurface imaging. In this paper, we further extend the concept to time domain radars for which the source is not separated from the antenna characteristics. Then, we provide insights on the application of the method to near-field conditions. Radar measurements were performed with the antenna at different heights over a perfect electrical conductor (PEC) and on a sandy soil with buried targets. For the PEC measurements, far-field filtering performed very well and also provided relatively good results in near-field conditions, except for the shortest range. Far-field measurements for the sand also provided good results, although the antenna transfer functions had to be corrected to account for the varying time domain radar source (drift). The radar image was not improved for the on-ground radar configuration. Future research will focus on near-field filtering of antenna effects using a recent generalization of the far-field model to near-field conditions. View full abstract»

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  • GPR and ERT combined analysis on the basis of advanced wavelet methodology: The Montagnole testing area

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    Ground Penetrating Radar (GPR) and Electric Resistivity Tomography (ERT) are well assessed and accurate geophysical methods for the investigation of subsurface geological sections. In this paper, we present the joint exploitation of these methods al the Montagnole (French Alps) experimental site with the final aim to study and monitor effects of possible catastrophic rockslides in transport infrastructures. It is known that factors as the ambiguity of geophysical field examination, the complexity of geological scenarios, and the low signal-to-noise ratio affect the possibility to build reliable physical-geological models of the investigated subsurface structure. Here, we applied for the GPR and ERT methods at Montagnole site, the recent advances in the wavelet theory and data mining. Wavelet approach was specifically used to achieve enhanced (e.g., coherence portraits) images resulting from the integration of the different geophysical fields. This methodology based on the matching pursuit combined with wavelet packet dictionaries permitted us to extract desired signals in different physical-geological conditions, even in presence of strongly noised data. Such tools as complex wavelets were employed to the coherence portraits, combined GPR-ERT coherency orientation angle, to name a few, enable performing non-conventional operations of integration and correlation in subsurface geophysics. The estimation of the above mentioned parameters proved useful not only for location of buried inhomogeneties but also for a rough estimation of their electromagnetic and related properties. Therefore, the combination of the above approaches has allowed to set-up a novel methodology, which may enhance reliability and confidence of each separate geophysical method and their integration. View full abstract»

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  • A comparison of phase-shift and one-port coaxial cell permittivity measurements for GPR applications

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (530 KB) |  | HTML iconHTML  

    The coarse and loose nature of unbound granular road materials presents a number of challenges for conventional permittivity characterisation approaches. An alternative that appears better suited to these materials involves measuring the phase-shift at discrete frequencies through a sample of known thickness. To validate this approach against more established methods, a comparison is required on materials that can be easily measured using either method. To this end phase-shift measurements were undertaken on a range of solid dielectric slabs including various types of stone, plastic and an artificial material. Permittivity predictions from this method were then compared to results from a one-port coaxial cell. As an additional comparison, and to better understand the results, the phase-shift test setup was also modelled using GPRMax software. To improve the predictions, reverberations within the test apparatus were minimized by isolating the direct wave using time-domain Blackman windowing. However, the narrow window necessary for this particular test setup also degraded the ability to detect frequency-dependent permittivity changes. Overall the phase-shift approach produced real relative permittivity predictions similar to that from the one-port coaxial cell. Despite limitations in the current approach, the results validate the phase-shift approach as a simple and rapid method of characterizing the permittivity of larger dielectric material samples of constant thickness. View full abstract»

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  • Near-subsurface imaging from a multistatic/single frequency scanner

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    We propose an approach for probing the near-subsurface based on the use of a single frequency combined with a multistatic configuration. Our goal is to retrieve the near-subsurface permittivity spatial distribution from measured electromagnetic fields. To that end, efforts have been done on the calibration procedure. In particular, the radiation pattern of the antenna is taken into account in the modeling of the scattering problem. We also preprocess the measured fields with an efficient method which takes profit of the spectral bandwidth properties of the scattered field allowing the removal of the residual interface contribution. Imaging results of shallowly buried target embedded in a high-losse medium are presented to assess the well-behavior of the proposed methodology. View full abstract»

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  • Applications of Ground Penetrating Radar in civil engineering — COST action TU1208

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1268 KB) |  | HTML iconHTML  

    This paper focuses on the use of Ground Penetrating Radar (GPR) in civil engineering. Open issues in this field are identified and desirable advances in GPR technology, application procedures, data processing algorithms and analysis tools, are addressed. European associations, institutes and consortia interested in this topic are mentioned, together with the main relevant international events. The new COST (European COoperation in Science and Technology) Action TU1208 “Civil Engineering Applications of Ground Penetrating Radar” is presented, started in April 2013: this interdisciplinary project offers important research opportunities and will strengthen European excellence in all the fields concerning the success of GPR technique, with a main focus on its applications in civil engineering. Four Working Groups (WGs) carry out the research activities: WGI focuses on the design of innovative GPR equipment, on the building of prototypes, as well as on the testing and optimization of new systems; WG2 focuses on the GPR surveying of pavement, bridges, tunnels and buildings, as well as on the sensing of underground utilities and voids; WG3 deals with the development of electromagnetic forward and inverse scattering methods and of advanced data processing algorithms; WG4 explores the use of GPR in fields different from civil engineering and the integration of GPR with other nondestructive testing techniques. The COST Action TU1208 is still open to the participation of new parties: in this paper, information is provided for scientists and scientific institutions willing to join the Action and participate to its activities. View full abstract»

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  • A reconfigurable stepped frequency GPR (GPR-R): The antenna subsystem

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    GPR-R technology fully exploits the unique advantages of the stepped frequency radar technique. A GPR equipment based on this technology has been recently developed by the authors: it is able to reconfigure its integration time and transmitted power vs. frequency in order to increase penetration capability and radiofrequency interference immunity. This paper describes the antenna subsystem of this radar. View full abstract»

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