Ground Penetrating Radar Devices Research Articles

Subsurface Utility Identification at ITERA Campus Using Multi-frequency Ground Penetrating Radar

Infrastructure development at the Sumatra Institute of Technology is growing rapidly, hence, it requires new utilities installation network such as cables and pipes to supply electricity and clean water. Installing new utility line, it is necessary to secure and know the existence and depth of the previously embedded utility network to avoid damage that could hamper the construction process or cause large losses. Accessing the sub-surface information, geophysical method, such as Ground Penetrating Radar (GPR) can be utilized for identifying buried utility networks, ensuring the safe installation of new utilities and preventing damage to existing embedded utilities. In this study, a GPR device with a frequency range 40 MHz-3.4 GHz comprising 5 tracks was employed. The acquired data underwent processing using GPR Insights software, generating a radargram cross-section that provides information about the subsurface.The results from the radargram reveal a hyperbolic reflection anomaly, signifying the presence of a utility network beneath the surface, suspected to be pipe and cable utilities. The utility network is detected at varying depths of 0.5 m, 0.8 m, 1 m, and 1.2 m at different distances. Furthermore, several anomalies in the form of hyperbolas are observed, suggesting potential utilities due to their continuity with other paths.

Recent methods of visualization used in the diagnosis and consolidation of historic structures

The subject addresses heritage objects that are subject to degradation processes caused by both natural and anthropogenic factors. One of the current solutions is directed towards a varied range of scientific instruments, thus facilitating the analysis and diagnosis of the concerned buildings, contributing also to the identification of materials and techniques used and providing information about any previous interventions of conservation attempts. Recent visualization methods used in the diagnosis and consolidation of historic structures can utilize both three-dimensional laser scanning technology and laser interferometry as a diagnostic method, as well as alternative methods such electrometry, magnetometry and ground penetrating radar devices. The subject aims to address how heritage objects can be secured using 3D scanning technologies. The case studies were conducted on the Bezdin Monastery Complex, the ”Saint Martyr Gheorghe” Church, the ”Saint Martyr Filimon” Monastery and the former Metropolitan Summer Residence in Sibiu. The selected case studies illustrate the methodology for obtaining and processing field data, as well as the use of this data in the diagnosis process and in selecting appropriate consolidation options for these historical structures based on obtained results. These technologies have provided specialists with the possibility of extracting vital information both in the diagnostic phase and throughout the implementation of restoration works. Advanced scanning technologies of today have enabled the creation of a database with the capability of providing pertinent information about a building’s past, starting from its initial stage, up to the completion of execution works, which significantly aids in facilitating the process of diagnostic analysis and structural calculation.

Design and Development of A New GPR System for Soil Detection

Soil is a key factor in many fields such as national food security and ecological environment construction. In recent years, as an important geophysical method, ground penetrating radar (GPR) is widely used in soil detection. However, the detection efficiency and data quality of some GPR devices need to be improved in complex surface environments. In this paper, a new soil-special GPR device is designed. This device adopts a new antenna with strong directivity and high resolution. The corresponding data acquisition software is developed by Labview. Combined with GPS system, the acquisition trajectory is located with 1 cm accuracy. Compared with the MALA GPR device, the new soil-special GPR device has achieved high resolution detection results.

Feasibility of Conventional Non-Destructive Testing Methods in Detecting Embedded FRP Reinforcements

Fiber-Reinforced Polymer (FRP) bars/strands are the most promising alternative to their steel counterparts for reinforcing concrete elements due to their resistance to corrosion, lighter weight, higher strength and better durability. However, very limited research has been conducted in relation to non-destructive testing (NDT) methods that are applicable to damage detection in FRP bars or the detection of FRP reinforcements embedded in concrete. The ability to assess the condition of the relatively new and unique FRP reinforcements will increase the confidence of the construction industry in their use as a reliable substitute for steel reinforcements. This paper investigates the ability of two of the most commonly used NDT methods, Ground Penetrating Radar (GPR) and Phased Array Ultrasonic (PAU), in detecting FRP bars/strands embedded in concrete elements. GPR and PAU tests were performed on two slab specimens reinforced with GFRP (Glass-FRP) bars, the most commonly used FRP bar, with variations in their depth, size and configuration, and a slab specimen with different types of available FRP reinforcements. The results show that GPR devices can detect GFRP bars/strands and CFRP (Carbon-FRP) strands to some extent, and their detectability increases with the increase in their antenna center frequency. On the contrary, PAU is only capable of detecting GFRP and CFRP strands. The results of this paper also emphasize the need for further research and developments related to NDT applications to embedded FRP bars.

An Integrated Framework for BIM Development of Concrete Buildings Containing Both Surface Elements and Rebar

As-built Building Information Models (BIM) are increasingly used to facilitate the management of all aspects of built infrastructure’s life cycle. Existing studies mainly focus on automating as-built BIM development for surface elements but often ignore embedded elements such as rebar due to the inaccessibility with typical sensing devices, such as image-based or time-of-flight-based methods. To tackle the issue, this research innovatively utilizes Ground Penetrating Radar (GPR) and the photogrammetry method together to generate BIMs for in-service buildings considering both surface elements (e.g., column, slab, wall) and rebar. As-built BIM for surface elements is developed at first and rebar is identified by using GPR. A calibration label is designed and attached to elements which are scanned by GPR device, and a series of images are captured from those elements and then used with other images to generate point clouds. Faster RCNN is utilized to recognize labels among all images. Then, an inverse photogrammetry approach is deployed to identify the scanned elements in BIM. By matching the recorded timestamps of GPR data and labeled images, links between the rebar in GPR data and elements in BIMs are successfully developed. Finally, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IFC</i> is developed to generate as-built BIM models. Six cases studies demonstrate the system provides a highly automated procedure to develop as-built BIM, and rebars could be efficiently localized and projected into corresponding elements in BIM.

A modified common midpoint approach for GPR radars

Ground Penetrating Radar (GPR) plays an important role among the non-destructive methods used to analyze, measure and collect data from pavement layers, building structures and archaeological sites. A GPR device consists of a radar able to get an image, technically called radargram, of the subsurface. Due to the decreasing costs of calculation power, it is now possible to analyze and interpret radargrams more efficiently than in past. While technological advancements and improvements in the post-processing of data have increased the power of this process, it is also important to consider survey technique as a key factor in nondestructive testing. The aim of this paper is to propose a modification of a well-known survey technique called Common Mid-Point (CMP). The conventional CMP survey technique requires that the transmitter and receiver of the GPR device be physically separated to survey a site. This provides the benefit of determining the speed of light in the host medium from the slant of the hyperbola reflection of a buried target. The CMP process unifies the inspection technology into a single device, making the use of GPR more accessible to robots on construction sites. The method documented in this paper is based on a mathematical model for adapting the conventional CMP for conventional GPR radar devices, in which transmitter and receiver cannot be separated physically.

Different techniques in detection of buried objects using ground-penetrating radar: A review

This literature reviews the work of researchers on ground-penetrating radar (GPR). This research consists of five sections starting from the first section that focuses on the general application and the advantage of the GPR system in comparison to other types of underground detection systems.&#x0D; The main function of the GPR system is to detect the object buried underground and at the end of the full scan, the output image represents the total signals detected by the receiver of the GPR device. One of the main applications of the GPR system is the detection of an underground object, the GPR scans the underground area and the output image represents the total of the signals detected by the receiver. The second section discusses methods for removing unwanted signals such as noise and direct waves from the output image of a GPR system.&#x0D; After removing the noise, the image requires further analysis to discover and interpret the buried object. The third section discusses the common methods used in the process of identifying buried objects. There are different types of buried objects and section four discusses the algorithms used to detect and identify landmines and explosive devices.&#x0D; Finally, the last section summarizes the paper that discussed the detection and identification process using smart algorithm technology. These types of algorithms are the most accurate, have a lower error rate and are cost-effective.

Development of Condition Assessment Index of Ballast Track Using Ground-Penetrating Radar (GPR).

The condition of the ballast is a critical factor affecting the riding quality and the performance of a track. Fouled ballast can accelerate track irregularities, which results in frequent ballast maintenance requirements. Severe fouling of the ballast can lead to track instability, an uncomfortable ride and, in the worst case, a derailment. In this regard, maintenance engineers perform routine track inspections to assess current and future ballast conditions. GPR has been used to assess the thickness and fouling levels of ballast. However, there are no potent procedures or specifications with which to determine the level of fouling. This research aims to develop a GPR analysis method capable of evaluating ballast fouling levels. Four ballast boxes were constructed with various levels of fouling. GPR testing was conducted using a GSSI (Geophysical Survey Systems, Inc.) device (400, 900, 1600 MHz), and a KRRI (Korea Railroad Research Institute) GPR device (500 MHz), which was developed for ballast tracks. The dielectric permittivity, scattering of the depth (thickness) values, signal strength at the ballast boundary, and area of the frequency spectrum were compared against the fouling level. The results show that as the fouling level increases, the former two variables increase while the latter two decrease. On the basis of these observations, a new integrated parameter, called a ballast condition scoring index (BCSI), is suggested. The BCSI was verified using field data. The results show that the BCSI has a strong correlation with the fouling level of the ballast and can be used as a fouling-level-indicating parameter.

Underground Pipeline Identification into a Non-Destructive Case Study Based on Ground-Penetrating Radar Imaging

Ground-penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in nondestructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR has proven its ability to work in electromagnetic frequency range for subsoil investigations, and it is a risk-reduction strategy for surveying underground various targets and their identification and detection. This paper presents the results of a case study which exceeds the laboratory level being realized in the field in a real case where the scanning conditions are much more difficult using GPR signals for detecting and assessing underground drainage metallic pipes which cross an area with large buildings parallel to the riverbed. The two urban drainage pipes are detected based on GPR imaging. This provides an approximation of their location and depth which are convenient to find from the reconstructed profiles of both simulated and practical GPR signals. The processing of data recorded with GPR tools requires appropriate software for this type of measurement to detect between different reflections at multiple interfaces located at different depths below the surface. In addition to the radargrams recorded and processed with the software corresponding to a GPR device, the paper contains significant results obtained using techniques and algorithms of the processing and post-processing of the signals (background removal and migration) that gave us the opportunity to estimate the location, depth, and profile of pipes, placed into a concrete duct bank, under a structure with different layers, including pavement, with good accuracy.

Development of GPR Device and Analysis Method to Detect Thickness of Ballast Layer

Insufficient ballast depth and fouled ballast have been pointed to as causes of settlement and track irregularity. Nondestructive testing methods such as Ground Penetrating Radar (GPR) are a preferred alternative to efficiently evaluate thickness and condition of railroad ballast. Data collected using commercial GPR devices show significant noise around and under sleepers. Furthermore, GPR data need attentive preprocessing and filtering of unnecessary noise before main analysis. In this study, to eliminate noise due to the sleeper, a GPR device with a transmitter and a receiver in a separate box is developed. In addition, an algorithm that can automatically detect the thickness of the ballast layer is also proposed. Comparison between data from the developed device and from a conventional device shows that the developed device can effectively eliminate noise. The trial pit measurements show that the proposed algorithm with the developed GPR device can accurately determine the thickness of ballast.

Application of Ground Penetration Radar and Light Weight Deflectometer for Pavement Quality Control and Quality Assessment

Pavement evaluation requires the frequent assessment of structural and functional condition. Earlier functional assessment of pavement were rapid and non destructive whereas structural evaluation required destructive testing. With growth in technology the light weight deflectometer (LWD) and ground penetrating radar (GPR) replaced the destructive testing in most part of the world. This paper highlights the use of LWD and GPR as non destructive testing tool in pavement evaluation. LWD and GPR test were conducted on the granular material to investigate the composite modulus of layer for their quality assessment. LWD test results were found to be significantly affected by the base plate diameter, contact between plate and surface layer, whereas drop height does not show significant difference on composite modulus. GPR technology has showed its versatility in pavement layer thickness evaluation, void and crack detection, and sub surface exploration. Ground coupled GPR has been used for subsurface exploration. At project level pavement management system, the combined use of GPR and deflection testing device has resulted in effective monitoring of pavement structural capacity. Hence LWD and GPR had showed its effectiveness for quality control and quality assurance (QC/QA) in PMS.

A novel 3D GPR image arrangement for deep learning-based underground object classification

ABSTRACT Ground-penetrating radar (GPR) is widely used for detecting buried underground object. Deep learning technique is recently being adopted into this field thanks to its powerful image classification capacity. However, it uses only GPR B-scan images, although multichannel GPR device can provide more informative three-dimensional (3D) data for underground object. In this study, a novel deep learning-based underground object classification method is proposed by using two-dimensional (2D) grid image which consists of several B-scan and C-scan images. Spatial information of an underground object can be well represented in the 2D grid image. The 2D grid images are then used to train deep convolutional neural networks. The proposed method is experimentally validated by field data collected from urban roads in Seoul, South Korea. The performance is also compared to a conventional method which uses only B-scan images. The proposed method successfully classifies cavity, pipe, manhole and subsoils background having very small false-positive errors.

Large‐area high‐resolution ground‐penetrating radar measurements for archaeological prospection

AbstractTraditionally, ground‐penetrating radar (GPR) measurements for near‐surface geophysical archaeological prospection are conducted with single‐channel systems using GPR antennae mounted in a cart similar to a pushchair, or towed like a sledge behind the operator. The spatial data sampling of such GPR devices for the non‐invasive detection and investigation of buried cultural heritage was, with very few exceptions, at best 25 cm in cross‐line direction of the measurement. With two or three persons participating in the fieldwork, coverage rates between a quarter hectare and half a hectare per day are common, while frequently considerably smaller survey areas at often coarse measurement spacing have been reported. Over the past years, the advent of novel multi‐channel GPR antenna array systems has permitted an enormous increase in survey efficiency and spatial sampling resolution. Using GPR antenna arrays with up to 16 channels operating in parallel, in combination with automatic positioning solutions based on real‐time kinematic global navigation satellite systems or robotic total‐stations, it has become possible to map several hectares per day with as little as 8 cm cross‐line and 4 cm in‐line GPR trace spacing. While this dramatic increase in coverage rate has a positive effect on the reduction of costs of GPR surveys, and thus its more widespread use in archaeology, the increased spatial sampling for the first time allows for the high‐resolution imaging of relatively small archaeological structures, such as for example 25 cm wide post‐holes of Iron Age buildings or the brick pillars of Roman floor heating systems, permitting much improved archaeological interpretations of the collected data. We present the state‐of‐the‐art in large‐scale high‐resolution archaeological GPR prospection, covering hardware and software technology and fieldwork methodology as well as the closely related issues of processing and interpretation of the huge data sets. Application examples from selected European archaeological sites illustrate the progress made.

Concrete Bridge Deck Deterioration Assessment Using Ground Penetrating Radar (GPR)

Ground penetrating radar (GPR) has become an effective means for assessing deterioration in concrete bridge decks. While success has been demonstrated, the method is still not adopted widely. Constant technical development is making such high speed GPR mapping more affordable with systems more widely available and easier to deploy. The American Society for Testing and Materials (ASTM) has a standard procedure for performing bridge deck deterioration using GPR. The current standard, initially written for air-launched GPR devices and then modified to include ground-coupled GPRs, has many simplifying assumptions that could lead to fallacious evaluations. Both field experience and numerical simulations indicate that ground-coupled GPR systems are preferable to air-launched GPRs in this application, delivering larger signal-to-noise and higher spatial resolution data, which enhance extraction of both electromagnetic wave velocity and attenuation. We describe advances in analysis and interpretation that go beyond the current ASTM approach which ignores the impact of depth and other variables. We demonstrate these advances using a high speed, ground-coupled GPR system with examples of deck deterioration mapping. We describe the workflow for using GPR to evaluate the deterioration of concrete bridge decks, highlight the basic interpretation assumptions, demonstrate successful applications and discuss limitations with the methodology.

Experimental Analysis of 3D Cracking in Drying Soils Using Ground-Penetrating Radar

This paper describes the capabilities of a novel technique to investigate crack formation and propagation in drying soils. The technique is a relatively simple, non-destructive indirect technique using a ground-penetrating-radar (GPR) system to detect cracks that form and propagate inside a soil specimen during desiccation. Although GPR devices have been used for multiple applications, their use in soils for the detection of small desiccation cracks has not been demonstrated yet. The experiment and the methodology used to test the accuracy of a small compact commercial GPR device for crack identification are described. The main objective was to identify what type of signals and what crack width and separation between them can be detected using the GPR device. The results indicate that cracks of 1 or 2 mm wide can be detected depending on its position and shape, whereas sub-millimetre cracks are undetectable with the currently existing devices in the market. Regardless of this limitation, the GPR method can be useful to find time-related bounds of when the cracks appear, to point at their location and sometimes at the separation between two of them.Detection of cracks with origin at the bottom or within the specimen was accomplished with this system. Distances of 5 cm or more between cracks can be detected and measured, as well, with accuracy.

Comparative evaluation of nondestructive devices for measuring pavement thickness in the field

Estimating pavement surface thicknesses without requiring large footprint equipment or pavement repairs is critical for the structural evaluation of airfield pavement. A research team from the U.S. Army Engineer Research and Development Center conducted an evaluation of eleven nondestructive technologies, including eight ground penetrating radar (GPR) devices and three wave propagation technologies, on twenty-one hot-mix asphalt concrete (AC) and nineteen portland cement concrete (PCC) test locations with varying pavement thicknesses. The different technologies were used to estimate pavement thickness over predetermined test points. For each pavement structure, a core was extracted from one of the test points to provide calibration data of each testing device for data refinement. The accuracy of each technology was quantified by calculating the absolute difference between the actual core measurement and the estimated thickness measurement. The results from the devices tested led to the conclusion that separate devices are required on AC and PCC for optimal performance. The ultrasonic tomography and impact echo devices worked best on PCC surfaces, and the 1GHz horn antenna GPR devices performed best on AC surfaces. The side-by-side testing demonstrated the capabilities of the technologies on varying pavement structures without discrepancies that would likely occur when comparing one set of results to those from a different study.

The Use of Ground-Penetrating Radar to Locate Tree Roots

Until recently the only way to investigate tree root architecture and distribution involved the physical removal of soil. However, in the past decade, ground-penetrating radar (GPR), which has been used in many other industries for about 30 years, has been used to study tree roots. GPR is relatively new to Australia and the aim of this research was to assess its spatial accuracy and ability to detect tree roots. Three experiments were conducted using a 900 MHz GPR device (Tree Radar®). The first experiment tested the ability of GPR to detect roots of sizes 10 mm, 20 mm, and 40 mm in diameter at depths of 200 mm, 400 mm, and 800 mm, while the second experiment tested its capacity to resolve two roots placed close together. Roots of 20–30 mm in diameter were placed in pairs at 20 mm, 40 mm, and 80 mm apart at depths of 200 mm, 400 mm, and 800 mm. The final experiment used GPR to analyze the in situ root system of a small Pistacia chinensis (Chinese pistachio) after which the root system was excavated using an AirSpade® and counts of root numbers were undertaken and compared with the predicted results. GPR detected and discriminated tree roots accurately at 200 mm depth, but as the depth increased to 400 mm and then to 800 mm, the levels of error increased, probably due to the choice of antenna available for the experiments, leading to the presence of phantom roots in some results and the misdetection of true roots in others. Confounding of the signal with unexpected interference or inadequate signal processing was most likely the cause. In the final experiment, GPR missed many small roots in the trenches close to the tree and appeared to detect multiple roots as one. In the outer trenches, GPR predicted 52 roots in total but excavation revealed only one in these disturbed urban soils.

Detection of Implanted Devices In Underground By Using UWB Penetrating Radar with Support of PN Code

Ground Penetrating Radar (GPR) is a method for estimation of underground structures by sending and receiving electromagnetic. With Ultra Wideband (UWB) signal, GPR is expected to improve resolution for detection of objects in underground. But there are problems that attenuation of waves from deep objects and confusion of waves from different objects. We propose a signal processing for UWB GPR to improve detection accuracy by applying interference cancellation technique for wireless communication. To obtain gains, we use a long transmitting signal with PN codes remain in low instantaneous power. Then estimating and cancelling reflect waves from received signals, we detect objects recursively. Position estimation of medical implanted devices can be also improved by using the technique. With comparing GPR and medical devices, we study a signal processing for position estimation for objects in dielectric substances.

A consistent approach for processing and interpretation of data from concrete bridge members collected with a hand-held GPR device

Non-destructive testing (NDT) techniques have become important means to inspect concrete bridge members. In particular, ground penetrating radar (GPR) has the ability to provide valuable information with respect to geometry and location of reinforcing bars, and, in some cases, areas of deterioration such as corrosion or potential delaminations. In this paper, we present a consistent methodology to process and interpret data from a hand-held GPR device. These small devices are often used by practitioners to more accurately inspect areas of interest while traffic control is maintained. Our methodology uses an exact non-linear time-depth relationship and cross-correlation to locate and visualize reflectors. The polarity and amplitude of the reflected pulse is also extracted and gives further information on the type of reflector, e.g., air vs. steel. Data collected and processed from three laboratory mock-up specimens are presented and discussed, and further work is proposed.