A review of pavement assessment using ground penetrating radar (GPR)

The use of GPR to obtain information on pavement structures has greatly developed over the past 20 to 30 years. The early 1980’s saw the first major developments of GPR for pavement applications and it is now an accepted technique for pavement investigation. GPR has a proven ability to obtain a variety of information on parameters relating to the structure and materials of the pavement. Despite this, several hindrances to wider use of the technique exist, and there is a requirement to address a number of both perceived and real limitations of GPR use for pavement investigation. This paper aims to provide an up to date discussion and summary of the current and developing uses of GPR for pavement investigation, through reference to previous work and ongoing research,including that conducted by the authors. This paper is intended for both GPR specialists and pavement engineers, and reports the ability of GPR to obtain good data for the various uses described, and discusses the applicability,limitations, and scope of GPR for further developments in pavement investigation

GPR applications across Engineering and Geosciences disciplines in Italy: a review

In this paper, a review of the main ground-penetrating radar (GPR) applications, technologies, and methodologies used in Italy is given. The discussion has been organized in accordance with the field of application, and the use of this technology has been contextualized with cultural and territorial peculiarities, as well as with social, economic, and infrastructure requirements, which make the Italian territory a comprehensive large-scale study case to analyze. First, an overview on the use of GPR worldwide compared to its usage in Italy over the history is provided. Subsequently, the state of the art about the main GPR activities in Italy is deepened and divided according to the field of application. Notwithstanding a slight delay in delivering recognized literature studies with respect to other forefront countries, it has been shown how the Italian contribution is now aligned with the highest world standards of research and innovation in the field of GPR. Finally, possible research perspectives on the usage of GPR in Italy are briefly discussed

A comparison between different central frequencies of investigation in buried utility detection through GPR: a study case

Ground Penetrating Radar (GPR) has proved to provide a high reliability in detecting several subsurface features such as water and gas pipes, energy and telecommunication supplies, water reservoirs or air voids. The present work faces a comparison between different central frequencies of investigation to reconstruct the network of utilities located underneath a paved surface and to understand the best strategy of analysis to undertake. To this purpose, a 757 m2 paved parking situated in London was used as test site and divided into three smaller areas. Central frequencies of investigation of 250 MHz, 400 MHz, 500 MHz, 1000 MHz, 2000 MHz, and 4000 MHz were selectively employed over these areas, and the outcomes from the 250 MHz, 500 MHz, and 1000 MHz are here analyzed. The analysis of the data has detected the presence of several utility lines with different placements than those represented within the design charts. Useful insights about the performances of different central frequencies of investigation are here discussed, as well as the usefulness of GPR in validating information collected by visual inspections and available from cartographic maps

Ground Penetrating Radar in the Detection of Subsurface Cavities Related to Sinkhole Activity in Florida

The Florida peninsula is underlain by limestone undergoing continuous solution process resulting in subsurface cavity formation. Increased land development has led to costly structural damage and water supply contamination due to surface subsidence and collapse in areas overlying such cavities. Conventional drilling methods cannot guarantee detection of isolated cavities. A geophysical technique known as ground penetrating radar (GPR) is a non-destructive method in geotechnical investigation capable of surveying large areas quickly and efficiently. GPR works as an echo sounder with a continuous similar graphic display. Cavities are identified by hyperbolic patterns caused by reflections from variations in electrical properties of anomalies as compared to the surrounding material. Due to irregular variations and inconsistencies in the properties of the naturally deposited soils and rocks, interpretation of the result from a radar survey is difficult to pre-determine without an actual field investigation. The intent of this study is to determine those circumstances under which GPR can be of use in the subsurface cavity detection investigations. The results indicate that subsurface conditions in north and central Florida are generally favorable and that this method can be extremely useful in determining trends in subsurface erosion

Nondestructive Evaluation of the Condition of Subsurface Drainage in Pavements Using Ground Penetrating Radar (GPR)

Subsurface drainage features are routinely incorporated in the design of pavement systems as they are believed to increase pavement service life provided that they are installed correctly and maintained. Maintenance, however, is challenging in that location and subsequent inspection of these systems can be time consuming and laborious. With this in mind, some departments of transportation have turned to ground penetrating radar as one means to rapidly locate subsurface drainage features in pavements and thus alleviate some of the cost and complexity of maintaining these systems, but with mixed results. In this context, this study pursued a two-pronged approach to improve GPR-based location of sub-pavement drainage systems, involving: (1) software-based signal processing and (2) modifications of hardware test configurations. From a signal processing perspective, two complementary signal processing approaches were developed in this work. Method 1 involved algorithms that are designed to reduce GPR signal background clutter and noise by taking advantage of the somewhat uniform nature of the strata underlying constructed pavements and to systematically remove anomalous signals. Method 2 focused on enhancing 2-D image quality to facilitate recognition of hyperbolic signal returns indicative of drain detection. From a hardware perspective, field experiments were also carried out in this work to validate the signal processing algorithms and assess the potential for alternative antenna configurations to enhance detection success. Five different antenna configurations were tested in total. When employed in field settings, the signal processing algorithms demonstrated an ability to routinely detect X-drains (shallow depth, PVC) with 2-3 false alarms per successful detection. Similarly, all known K-drains (moderate depth, metal/clay) in the studied field test regions were successfully identified, although each successful K-drain detection was accompanied by a significant number of potential false alarms. Beyond these signal conditioning related findings, additional recommendations for field deployed GPR survey line selection, antennae configuration, and frequency selection are also provided

Electromagnetic investigation of abandoned mines in the Galena, KS, area

"As part of an investigation aimed at mitigating the hazards caused by abandoned mine openings, the U.S. Bureau of Mines conducted a series of electromagnetic surveys in the Galena, Kansas, area of the Tri- State Mining District. The application of monostatic ground- penetrating radar (GPR) and inductive electromagnetic methods for detecting and delineating hazardous mine openings and attendant features was demonstrated to be feasible for shallow mine workings (i.e., less than 35 ft) occurring below flat-lying areas. Accurate determinations of depth to a mine roof appeared to be limited to roughly 20 ft using the GPR method. Features such as mine voids, fractures, and zones of subsidence were located beneath the mainstreet (state highway 26) site using the GPR system. Both the GPR and inductive electromagnetic techniques satisfactorily located mine openings and pillars at the hell's half acre site. Geophysical interpretations were supported by exploratory drilling and mine maps." - NIOSHTIC-2NIOSH no. 10007652199

Combined use of GPR and Other NDTs for road pavement assessment: an overview

Roads are the main transportation system in any country and, therefore, must be maintained in good physical condition to provide a safe and seamless flow to transport people and goods. However, road pavements are subjected to various defects because of construction errors, aging, environmental conditions, changing traffic load, and poor maintenance. Regular inspections are therefore recommended to ensure serviceability and minimize maintenance costs. Ground-penetrating radar (GPR) is a non-destructive testing (NDT) technique widely used to inspect the subsurface condition of road pavements. Furthermore, the integral use of NDTs has received more attention in recent years since it provides a more comprehensive and reliable assessment of the road network. Accordingly, GPR has been integrated with complementary NDTs to extend its capabilities and to detect potential pavement surface and subsurface distresses and features. In this paper, the non-destructive methods commonly combined with GPR to monitor both flexible and rigid pavements are briefly described. In addition, published work combining GPR with other NDT methods is reviewed, emphasizing the main findings and limitations of the most practical combination methods. Further, challenges, trends, and future perspectives of the reviewed combination works are highlighted, including the use of intelligent data analysis.Xunta de Galicia | Ref. ED431F 2021/08Ministerio de Ciencia e Innovación | Ref. RYC2019–026604-