Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970582
V. Kopeikin, V. Kuznetsov, P. Morozov, A. Popov, A. Berkut, S. Merkulov
A big fragment of Chelyabinsk meteorite (February 15, 2013) fell to the western part of Chebarkul Lake, South Ural, Russia, making a breach in the ice cover. Field measurements done during March 12-14, 2013 revealed a steep dip of the hard bottom, west of the ice-hole. This bottom anomaly, accompanied by a local perturbation of the lower ice surface, has been interpreted as the meteorite impact site. Subsequent excavation of a 650 kg boulder with melted surface confirmed our hypothesis.
{"title":"GPR inspection of the Chelyabinsk meteorite impact site at the Chebarkul Lake bottom","authors":"V. Kopeikin, V. Kuznetsov, P. Morozov, A. Popov, A. Berkut, S. Merkulov","doi":"10.1109/ICGPR.2014.6970582","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970582","url":null,"abstract":"A big fragment of Chelyabinsk meteorite (February 15, 2013) fell to the western part of Chebarkul Lake, South Ural, Russia, making a breach in the ice cover. Field measurements done during March 12-14, 2013 revealed a steep dip of the hard bottom, west of the ice-hole. This bottom anomaly, accompanied by a local perturbation of the lower ice surface, has been interpreted as the meteorite impact site. Subsequent excavation of a 650 kg boulder with melted surface confirmed our hypothesis.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133417851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970450
L. Krysiński, J. Sudyka
The paper discusses the diagnostic abilities of the 3D imaging GPR technique on a practical level, applied to data collected by frequency-domain equipment in reflection configuration and visualized using the method of horizontal slices. This method is particularly efficient in the detection of reinforcement and large infrastructural objects of linear shape. It is especially interesting that the method also allows for the detection of joints and cracks, which are characterized by very weak GPR response. In this case several questions appear as to the nature of response generation and the features of the medium structure which are represented in the scattered signal. The scanned pavement has several layers of different ages and construction styles, and the GPR record illustrates large efficiency of this technique in diagnostics of the joint networks hidden below the asphalt overlay. The example proves reliability of the weak response corresponding to the top of the joints. Some problems related to chronology of responses corresponding to different depth of the medium were discussed. A specific asymmetric response corresponding to two horizontally layered constructions contacting along vertical plane was noted and described as well.
{"title":"Efficiency of 3D imaging in GPR diagnostics of joints and vertical construction contacts","authors":"L. Krysiński, J. Sudyka","doi":"10.1109/ICGPR.2014.6970450","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970450","url":null,"abstract":"The paper discusses the diagnostic abilities of the 3D imaging GPR technique on a practical level, applied to data collected by frequency-domain equipment in reflection configuration and visualized using the method of horizontal slices. This method is particularly efficient in the detection of reinforcement and large infrastructural objects of linear shape. It is especially interesting that the method also allows for the detection of joints and cracks, which are characterized by very weak GPR response. In this case several questions appear as to the nature of response generation and the features of the medium structure which are represented in the scattered signal. The scanned pavement has several layers of different ages and construction styles, and the GPR record illustrates large efficiency of this technique in diagnostics of the joint networks hidden below the asphalt overlay. The example proves reliability of the weak response corresponding to the top of the joints. Some problems related to chronology of responses corresponding to different depth of the medium were discussed. A specific asymmetric response corresponding to two horizontally layered constructions contacting along vertical plane was noted and described as well.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131689670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970555
C. T. Johnson, R. Evans
The hydration reaction between water and cement governs both the rate of strength gain in fresh concrete and also the final strength of hardened concrete. These strength properties are typically assessed by casting small samples (often cubes) taken from the fresh concrete and conducting destructive strength tests at selected days after casting. The hydration reaction causes a reduction in free water content in the concrete mix over time. The dielectric permittivity of a material is influenced by free water content, and thus ground penetrating radar (GPR) offers the potential to assess changes taking place during hydration. This paper reports a study where 45 concrete specimens, consisting of 3 different concrete mix designs, were cast and tested over a period of 92 days to establish both the changes in dielectric permittivity (determined from time domain GPR data) and the strength gain in the concrete (determined from compressive strength testing). Results showed a strong correlation between decreasing dielectric permittivity with increasing age (and increasing compressive strength) for each concrete mix design, and indicated the potential for GPR to be used as a rapid, nondestructive method for assessing hydration rate and strength gain as concrete changes from the freshly mixed to hardened state.
{"title":"Non-destructive assessment of the rate of hydration and strength gain of concrete","authors":"C. T. Johnson, R. Evans","doi":"10.1109/ICGPR.2014.6970555","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970555","url":null,"abstract":"The hydration reaction between water and cement governs both the rate of strength gain in fresh concrete and also the final strength of hardened concrete. These strength properties are typically assessed by casting small samples (often cubes) taken from the fresh concrete and conducting destructive strength tests at selected days after casting. The hydration reaction causes a reduction in free water content in the concrete mix over time. The dielectric permittivity of a material is influenced by free water content, and thus ground penetrating radar (GPR) offers the potential to assess changes taking place during hydration. This paper reports a study where 45 concrete specimens, consisting of 3 different concrete mix designs, were cast and tested over a period of 92 days to establish both the changes in dielectric permittivity (determined from time domain GPR data) and the strength gain in the concrete (determined from compressive strength testing). Results showed a strong correlation between decreasing dielectric permittivity with increasing age (and increasing compressive strength) for each concrete mix design, and indicated the potential for GPR to be used as a rapid, nondestructive method for assessing hydration rate and strength gain as concrete changes from the freshly mixed to hardened state.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124215335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970434
M. Fedorov, L. Fedorova, A. Omelyanenko, G. Kulyandin
Transformation of ice cover relief occurs during its freeze-up and by the action of hydro-meteorological factors. This article is dedicated to study of the formation of the Lena River ice cover based on a decade measurements in the hydrological station “Tabaga” (distance is 2 km). Two methods were applied for measuring the thickness of river ice: drilling method and GPR method. GPR data were obtained by GPR OKO-2 with antenna unit AB-400 (“Logis” LLC., Russia). Discrete drilling data (step is 100 m) and continuous GPR data of decade river - ice thickness measurements (distance between the probe points is 1 m) were presented. GPR data has shown an increase of average value of ice thickness from 93 cm to 142 cm from December to April, which corresponds to observations from the drilling data. Continuous GPR data provides more information and it reflects changes of river ice relief much more exactly than the drilling data. The ability of GPR for determining the dynamics of the seasonal variations in thickness of the Lena River ice cover is demonstrated.
{"title":"Study of formation of Lena River ice cover according of decade measurements by GPR","authors":"M. Fedorov, L. Fedorova, A. Omelyanenko, G. Kulyandin","doi":"10.1109/ICGPR.2014.6970434","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970434","url":null,"abstract":"Transformation of ice cover relief occurs during its freeze-up and by the action of hydro-meteorological factors. This article is dedicated to study of the formation of the Lena River ice cover based on a decade measurements in the hydrological station “Tabaga” (distance is 2 km). Two methods were applied for measuring the thickness of river ice: drilling method and GPR method. GPR data were obtained by GPR OKO-2 with antenna unit AB-400 (“Logis” LLC., Russia). Discrete drilling data (step is 100 m) and continuous GPR data of decade river - ice thickness measurements (distance between the probe points is 1 m) were presented. GPR data has shown an increase of average value of ice thickness from 93 cm to 142 cm from December to April, which corresponds to observations from the drilling data. Continuous GPR data provides more information and it reflects changes of river ice relief much more exactly than the drilling data. The ability of GPR for determining the dynamics of the seasonal variations in thickness of the Lena River ice cover is demonstrated.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121453379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970556
R. Hamrouche, T. Saarenketo
The need for more effective road condition management policies and practices has been growing rapidly over the last few years. A key word in this development is “focus” and for that more accurate and reliable continuous NDT survey methods, such as GPR, are needed. In asphalt thickness surveys a problem has been how to calculate/estimate the dielectric value of the asphalt. Thus far this has been done using drill cores or using the surface reflection technique. Within this context, this study is aimed at defining an accurate coreless method to calculate the average dielectric value of the whole asphalt layer of a road pavement using GPR (horn antennas). To accomplish this, the WARR (Wide Angle Reflection and Refraction) technique is applied. The principle is based on the resolution of a system of two nonlinear equations with two unknowns (asphalt thickness and electromagnetic wave velocity) using reflection the different time shift. An initial validation under controlled conditions was conducted and then followed by a series of measurements on a dedicated test field in order to validate and check the accuracy of the results given by our calculations. The results obtained are promising and a series of tests on real roads are under preparation.
{"title":"Improvement of a coreless method to calculate the average dielectric value of the whole asphalt layer of a road pavement","authors":"R. Hamrouche, T. Saarenketo","doi":"10.1109/ICGPR.2014.6970556","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970556","url":null,"abstract":"The need for more effective road condition management policies and practices has been growing rapidly over the last few years. A key word in this development is “focus” and for that more accurate and reliable continuous NDT survey methods, such as GPR, are needed. In asphalt thickness surveys a problem has been how to calculate/estimate the dielectric value of the asphalt. Thus far this has been done using drill cores or using the surface reflection technique. Within this context, this study is aimed at defining an accurate coreless method to calculate the average dielectric value of the whole asphalt layer of a road pavement using GPR (horn antennas). To accomplish this, the WARR (Wide Angle Reflection and Refraction) technique is applied. The principle is based on the resolution of a system of two nonlinear equations with two unknowns (asphalt thickness and electromagnetic wave velocity) using reflection the different time shift. An initial validation under controlled conditions was conducted and then followed by a series of measurements on a dedicated test field in order to validate and check the accuracy of the results given by our calculations. The results obtained are promising and a series of tests on real roads are under preparation.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117160026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970553
S. Pennock, C. Jenks
The condition of roads and pavements near their surfaces is of interest to asset management, in particular of the roads and pavement assets, but also of assets buried under the roads or pavements such as cables or pipes. In many cases the decay of the near surface material results in small air or water filled regions within the tarmac/concrete/stone structure. The decay causes little change in the electromagnetic reflection or delay characteristics of these regions as measured by traditional GPR equipment. Signals launched along the surface are diffracted out of the surface by fractures and discontinuities within the surface. The change between a uniform and a fractured surface is seen to be more readily apparent in the direction normal to the surface, particularly at higher frequencies above about 3 GHz for fractures and for voids of the order of about 2 mm and above. Finite Difference Time Domain simulations and initial microwave frequency measurements indicate significant changes in diffracted signals levels are observed over sufficiently fractured regions.
{"title":"Road surface and pavement condition assessment by high frequency GPR diffraction","authors":"S. Pennock, C. Jenks","doi":"10.1109/ICGPR.2014.6970553","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970553","url":null,"abstract":"The condition of roads and pavements near their surfaces is of interest to asset management, in particular of the roads and pavement assets, but also of assets buried under the roads or pavements such as cables or pipes. In many cases the decay of the near surface material results in small air or water filled regions within the tarmac/concrete/stone structure. The decay causes little change in the electromagnetic reflection or delay characteristics of these regions as measured by traditional GPR equipment. Signals launched along the surface are diffracted out of the surface by fractures and discontinuities within the surface. The change between a uniform and a fractured surface is seen to be more readily apparent in the direction normal to the surface, particularly at higher frequencies above about 3 GHz for fractures and for voids of the order of about 2 mm and above. Finite Difference Time Domain simulations and initial microwave frequency measurements indicate significant changes in diffracted signals levels are observed over sufficiently fractured regions.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117233038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970561
W. Uddin
Pavement asset management requires accurate and rapid measurement of asphalt layer thickness for reliable backcalculation of modulus values of pavement layers from nondestructive deflection tests. Also needed are measurements of layer delamination, surface cracking, and other distresses. Top-down cracking in the longitudinal wheel path of thick asphalt highway pavement is a major distress problem. The objective of this paper is to evaluate several nondestructive testing technologies that can be operated at highway speed to assess asphalt thickness and surface cracking depth. This paper presents key findings of an extensive literature review of GPR equipment and data interpretation methodologies. The study supports that nondestructive GPR technology has evolved over the last three decades to measure pavement layer thickness and delamination accurately, which is more cost-effective than extracting cores. The study did not find a field technology that can operate at highway speeds for mapping pavement surface cracking and its penetration depth. However, GPR remote sensing has the potential to map the penetration depth of top-down cracking from the surface through asphalt layer thickness.
{"title":"An overview of GPR applications for evaluation of pavement thickness and cracking","authors":"W. Uddin","doi":"10.1109/ICGPR.2014.6970561","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970561","url":null,"abstract":"Pavement asset management requires accurate and rapid measurement of asphalt layer thickness for reliable backcalculation of modulus values of pavement layers from nondestructive deflection tests. Also needed are measurements of layer delamination, surface cracking, and other distresses. Top-down cracking in the longitudinal wheel path of thick asphalt highway pavement is a major distress problem. The objective of this paper is to evaluate several nondestructive testing technologies that can be operated at highway speed to assess asphalt thickness and surface cracking depth. This paper presents key findings of an extensive literature review of GPR equipment and data interpretation methodologies. The study supports that nondestructive GPR technology has evolved over the last three decades to measure pavement layer thickness and delamination accurately, which is more cost-effective than extracting cores. The study did not find a field technology that can operate at highway speeds for mapping pavement surface cracking and its penetration depth. However, GPR remote sensing has the potential to map the penetration depth of top-down cracking from the surface through asphalt layer thickness.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115175056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970451
S. Pennock, T. M. Abed, G. Curioni, D. Chapman, U. E. John, C. Jenks
It has been observed that the corrosion of iron pipes in soil can produce variations in ground conductivity around the pipe, and that the visibility of such pipes to GPR can be greatly reduced. This new investigation and measurement of the permittivity and conductivity of soil contaminated by iron pipe corrosion products produces more accurate knowledge of permittivity and conductivity data and their likely spatial variation with distance from the corroding pipe. The experimental data are the result of monitoring accelerated corrosion over a period of several weeks and using TDR and direct conductivity measurement schemes. FDTD simulations of GPR signals show how the corrosion induced variation in the visibility of the pipe varies with the thickness and shape of the new spatial variations permittivity and conductivity. The results indicate that in the earlier stages of pipe corrosion use of lower GPR frequencies will still detect the pipe, although at lower spatial resolution.
{"title":"Investigation of soil contamination by iron pipe corrosion and its influence on GPR detection","authors":"S. Pennock, T. M. Abed, G. Curioni, D. Chapman, U. E. John, C. Jenks","doi":"10.1109/ICGPR.2014.6970451","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970451","url":null,"abstract":"It has been observed that the corrosion of iron pipes in soil can produce variations in ground conductivity around the pipe, and that the visibility of such pipes to GPR can be greatly reduced. This new investigation and measurement of the permittivity and conductivity of soil contaminated by iron pipe corrosion products produces more accurate knowledge of permittivity and conductivity data and their likely spatial variation with distance from the corroding pipe. The experimental data are the result of monitoring accelerated corrosion over a period of several weeks and using TDR and direct conductivity measurement schemes. FDTD simulations of GPR signals show how the corrosion induced variation in the visibility of the pipe varies with the thickness and shape of the new spatial variations permittivity and conductivity. The results indicate that in the earlier stages of pipe corrosion use of lower GPR frequencies will still detect the pipe, although at lower spatial resolution.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125841448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970557
T. Kind, C. Trela, M. Schubert, J. Wostmann
Time slices of very dense GPR measurements carried out at concrete with a real point distance of less than 10 mm in x and y direction show weak reflection patterns besides the strong reflections of reinforcements. A repetition of these measurements with the same local geometrical precision at the same specimen shows the same reflection pattern. We suppose that the heterogeneity of concrete given by aggregates (e.g. gravel, broken granite) causes local weak scattering of the GPR waves and leads to reflection patterns in the GPR data. These reflection patterns can be explained by a superposition of multiple scatterings of single aggregates. So far these reflection patterns have been not recognized in standard time slices due to the large spacing (> 5 cm) between single profiles and because of the interpolation between the profiles. We investigate the characteristics of the volume scattering effects, caused by aggregates, at concrete blocks with two different grading curves. In a more general investigation we study the volume scattering of aggregates by using wooden boxes filled with only typical aggregates and an included defined reflector (metal plate). The thickness of the aggregate layer above the metal plate was varied between 20 cm and 40 cm. With a very dense measuring grid at the surface we are able to calculate the effective volume scattering and to analyze the distribution of the reflection amplitude of the included metal plate for different aggregate set-ups. Results of this study confirm that the weak reflection patterns in concrete can be explained by aggregate scattering and have a direct correlation to the penetration depth of GPR in concrete.
{"title":"Aggregates scattering of GPR waves in concrete","authors":"T. Kind, C. Trela, M. Schubert, J. Wostmann","doi":"10.1109/ICGPR.2014.6970557","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970557","url":null,"abstract":"Time slices of very dense GPR measurements carried out at concrete with a real point distance of less than 10 mm in x and y direction show weak reflection patterns besides the strong reflections of reinforcements. A repetition of these measurements with the same local geometrical precision at the same specimen shows the same reflection pattern. We suppose that the heterogeneity of concrete given by aggregates (e.g. gravel, broken granite) causes local weak scattering of the GPR waves and leads to reflection patterns in the GPR data. These reflection patterns can be explained by a superposition of multiple scatterings of single aggregates. So far these reflection patterns have been not recognized in standard time slices due to the large spacing (> 5 cm) between single profiles and because of the interpolation between the profiles. We investigate the characteristics of the volume scattering effects, caused by aggregates, at concrete blocks with two different grading curves. In a more general investigation we study the volume scattering of aggregates by using wooden boxes filled with only typical aggregates and an included defined reflector (metal plate). The thickness of the aggregate layer above the metal plate was varied between 20 cm and 40 cm. With a very dense measuring grid at the surface we are able to calculate the effective volume scattering and to analyze the distribution of the reflection amplitude of the included metal plate for different aggregate set-ups. Results of this study confirm that the weak reflection patterns in concrete can be explained by aggregate scattering and have a direct correlation to the penetration depth of GPR in concrete.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126089244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-12-04DOI: 10.1109/ICGPR.2014.6970516
S. Pennock, O. Abdul-Latif, C. Jenks
The Superimposition technique offers an alternative to Fast Fourier Transform (FFT) and Inverse FFT calculations. side lobe levels are reduced with little or no increase in main lobe width, as opposed to standard windowing techniques where side lobe level reduction produces an increase in main lobe width with a resulting loss in resolution. The new technique uses repetitive superimpositions showing improvements over spatially variant apodization (SVA) techniques. A new normalisation scheme enhances side lobe reduction even further with no increase in main lobe width indeed it can reduce the main lobe width. The technique is seen to be more resilient to noise when appropriate multiple evaluations are chosen. The technique produces responses from reflections in GPR data that are resolved to responses much closer to a delta function than FFT/IFFT or SVA evaluations. When used in focussing algorithms the traditional hyperbolic characteristics of a B-scan are focussed into responses whose width in depth and plan position that are slightly better than half a wavelength of the bandwidth used. This is seen in theoretical data and in both data measured by commercial GPRs and in experimental data from a step frequency continuous wave based GPR. Theoretically the technique produces a strong indication of the permittivity of the ground the GPR measures are taken over, while in measured data the identification of the permittivity of the ground is less clear.
{"title":"Improved GPR image focussing with repetitive normalised Superimposition techniques","authors":"S. Pennock, O. Abdul-Latif, C. Jenks","doi":"10.1109/ICGPR.2014.6970516","DOIUrl":"https://doi.org/10.1109/ICGPR.2014.6970516","url":null,"abstract":"The Superimposition technique offers an alternative to Fast Fourier Transform (FFT) and Inverse FFT calculations. side lobe levels are reduced with little or no increase in main lobe width, as opposed to standard windowing techniques where side lobe level reduction produces an increase in main lobe width with a resulting loss in resolution. The new technique uses repetitive superimpositions showing improvements over spatially variant apodization (SVA) techniques. A new normalisation scheme enhances side lobe reduction even further with no increase in main lobe width indeed it can reduce the main lobe width. The technique is seen to be more resilient to noise when appropriate multiple evaluations are chosen. The technique produces responses from reflections in GPR data that are resolved to responses much closer to a delta function than FFT/IFFT or SVA evaluations. When used in focussing algorithms the traditional hyperbolic characteristics of a B-scan are focussed into responses whose width in depth and plan position that are slightly better than half a wavelength of the bandwidth used. This is seen in theoretical data and in both data measured by commercial GPRs and in experimental data from a step frequency continuous wave based GPR. Theoretically the technique produces a strong indication of the permittivity of the ground the GPR measures are taken over, while in measured data the identification of the permittivity of the ground is less clear.","PeriodicalId":212710,"journal":{"name":"Proceedings of the 15th International Conference on Ground Penetrating Radar","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126754450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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