An investigation into the railway ballast dielectric properties using different GPR antennas and frequency systems

Tosti, Fabio; Ciampoli, Luca Bianchini; Calvi, Alessandro; Alani, Amir M.; Benedetto, Andrea

doi:10.1016/j.ndteint.2017.10.003

Cited by 46 publications

(30 citation statements)

References 42 publications

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“…Having obtained the required amplitude values, the bulk permittivities of the three materials were then estimated using Equation (4) and are shown in Table 2. The bulk permittivities of both the sand and gravel are consistent with the values reported in [43,47], while that of the soil is higher than both materials because of the water content. Also, note that the bulk permittivity of the gravel is higher than that of the sand despite both materials having approximately the same measured bulk densities.…”

Section: Gpr Data Acquisition and Processingsupporting

confidence: 86%

“…It can be observed from Table 1 that the mass attenuation coefficient is relatively constant for all three materials therefore, an average value of 0.0775 was used in this study. The solid permittivity of soil and sand were obtained from [37], while that of gravel was obtained from [43]. In addition, a specific density of 2.65 g cm −3 [44] was adopted for all three materials.…”

Section: Methodsmentioning

confidence: 99%

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Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector

2019

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This study reports on the combination of data from a ground penetrating radar (GPR) and a gamma ray detector for nonintrusive depth estimation of buried radioactive sources. The use of the GPR was to enable the estimation of the material density required for the calculation of the depth of the source from the radiation data. Four different models for bulk density estimation were analysed using three materials, namely: sand, gravel and soil. The results showed that the GPR was able to estimate the bulk density of the three materials with an average error of 4.5%. The density estimates were then used together with gamma ray measurements to successfully estimate the depth of a 658 kBq ceasium-137 radioactive source buried in each of the three materials investigated. However, a linear correction factor needs to be applied to the depth estimates due to the deviation of the estimated depth from the measured depth as the depth increases. This new application of GPR will further extend the possible fields of application of this ubiquitous geophysical tool.

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Section: Gpr Data Acquisition and Processingsupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector

2019

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“…Due to the known physio-chemical attitude of fine-graded materials towards the retention of soil moisture [21][22][23], fouling and moisture are expected to magnify each other's influence on the EM…”

Section: Fouling/moisture Effects On the Surface Reflection Amplitudementioning

confidence: 99%

“…It is important to observe that the research focus on the subject area has also changed over the years [17]. The assessment of the geometry of the track-bed and its overall stability have been first a matter of research [10,19], whereas the focus has progressively moved towards the time-domain [14][15][16] and the frequency-domain [12,14,[20][21][22][23][24] analyses of the effects of fouling and fragmentation of ballast on the signal. In addition to this, new avenues in assessing quality of ballast aggregates have been recently explored by means of simulation-based approaches [25] and numerical models [26].…”

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confidence: 99%

Railway Ballast Monitoring by GPR: A Test Site Investigation

Ciampoli¹,

Calvi²,

D’Amico³

2019

Preprint

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Effective maintenance of railways requires a comprehensive assessment of the actual condition of the construction materials involved. In this regard, Ground-Penetrating Radar (GPR) stands as a viable alternative to the invasive and time-consuming traditional techniques for the inspection of these infrastructures. This work reports the experimental activities carried out on a test-site area within a railway depot in Rome, Italy. To this purpose, a 30 m-long railway section was divided into 10 sub-sections reproducing different various physical and structural conditions of the track-bed. In more detail, combinations of varying scenarios of fragmentation and fouling of the ballast were reproduced. The set-up was then investigated using different multi-frequency GPR horn antenna systems. The effects of the different physical conditions of ballast on the electromagnetic response of the material were analysed for each scenario using time-and frequencydomain signal processing techniques. Parallel to this, modelling was provided to estimate fouling content. Interpretation of results has proven the viability of the GPR method in detecting signs of decay at the network level, thereby proving this technique to be worthy of implementation in asset management systems.

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“…Three different methods are applied for the assessment of the relative dielectric permittivity, that is, the Time-Domain Signal-Picking (TDSP) technique (Wu et al, 1999), the Surface Reflection Method (SRM) (Scullion et al, 1994;Benedetto et al, 2015) and the theoretical model of the Volumetric Mixing Formula (Birchak et al, 1974). The results prove that the 1,000 MHz aircoupled antenna system provides reliable and stable data outputs in terms of relative dielectric permittivity for the assessment of railway ballast (Tosti et al, 2018). A further investigation is carried out on the container filled with ballast aggregates and silty soil in different quantities to simulate the fouling of the ballast.…”

Section: Laboratory Setup and Experimental Resultsmentioning

confidence: 92%

A Computer‐Aided Model for the Simulation of Railway Ballast by Random Sequential Adsorption Process

Benedetto

Ciampoli

Brancadoro

et al. 2017

Computer aided Civil Eng

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This article presents a computer‐aided multistage methodology for the simulation of railway ballasts using the Random Sequential Adsorption (RSA – 2D domain) paradigm. The primary stage in this endeavor is the numerical generation of a synthetic sample by a “particle sizing and positioning” process followed by a “compaction” process. The synthetic samples of ballast are then visualized in the Computer‐Aided Design (CAD) environment. The outcomes of the simulation are analyzed by comparison with the results of an experimental investigation carried out using a methacrylate container in which real samples of railway ballast are formed. A test of model reliability is carried out between the aggregates number and the grading curves of the synthetic sample and the real one. A validation is therefore performed using the ground‐penetrating radar (GPR) nondestructive testing (NDT) method and the finite‐difference time‐domain (FDTD) simulation developed in a computer‐aided environment. The results prove the viability and the applicability of the proposed modeling for the assessment of railway ballast conditions.

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An investigation into the railway ballast dielectric properties using different GPR antennas and frequency systems

Cited by 46 publications

References 42 publications

Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector

Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector

Railway Ballast Monitoring by GPR: A Test Site Investigation

A Computer‐Aided Model for the Simulation of Railway Ballast by Random Sequential Adsorption Process

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