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16 pages, 7929 KiB

Open AccessArticle

Analytical Models and Laboratory Measurements to Explore the Potential of GPR for Quality Control of Marble Block Repair through Resin Injections

by Marjan Izadi-Yazdanabadi, Azadeh Hojat, Luigi Zanzi, Saeed Karimi-Nasab and Diego Arosio

Appl. Sci. 2022, 12(3), 987; https://doi.org/10.3390/app12030987 - 19 Jan 2022

Cited by 3 | Viewed by 1469

Abstract

This work aims to analyze theoretically and with laboratory tests the sensitivity of high-frequency GPR (Ground-Penetrating Radar) to resin injections used in the building and ornamental stone industries to repair marble blocks before final slab cutting. We simulate uniform fractures in the laboratory [...] Read more.

This work aims to analyze theoretically and with laboratory tests the sensitivity of high-frequency GPR (Ground-Penetrating Radar) to resin injections used in the building and ornamental stone industries to repair marble blocks before final slab cutting. We simulate uniform fractures in the laboratory using small regular marble blocks and we compare the results of GPR tests with the analytical model of the thin bed reflections. We performed two series of GPR surveys with a 3 GHz antenna, progressively increasing the fracture thickness from 0.25 mm to 16 mm, to analyze the results on two simulated conditions: open fracture and repaired fracture. The repaired condition was simulated by substituting the resin layer with polyvinyl chloride (PVC) sheets because the permittivity of PVC is quite similar to the permittivity of epoxy resin. According to the analytical models, when a thin air-filled fracture is filled with resin, the received signal amplitude is expected to decrease by 33% (26% if resin is simulated with PVC). The results showed a very good match between the predictions and the real data observations when the fracture is thicker than 4 mm. Although the analytical and laboratory results show some deviations when the fracture is thinner than 4 mm, the qualitative trend of the amplitude variations is still consistent with the predictions and the 3 GHz antenna can resolve the change in the filling material down to the minimum tested thickness (0.25 mm). As a result, our findings validate the GPR method as a proper tool for nondestructive quality control of resin injections in marble fractures. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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14 pages, 5956 KiB

Open AccessFeature PaperArticle

Ground-Penetrating Radar Prospections to Image the Inner Structure of Coastal Dunes at Sites Characterized by Erosion and Accretion (Northern Tuscany, Italy)

by Adriano Ribolini, Duccio Bertoni, Monica Bini and Giovanni Sarti

Appl. Sci. 2021, 11(23), 11260; https://doi.org/10.3390/app112311260 - 27 Nov 2021

Cited by 4 | Viewed by 2176

Abstract

In this study we aimed to gain insights into dune formation and evolution from select coastal tracts of Northern Tuscany by inspecting their internal sedimentary architecture with Ground-Penetrating Radar (GPR) analysis. Erosion, equilibrium and accretion characterize the selected coastal tracts, and this analysis [...] Read more.

In this study we aimed to gain insights into dune formation and evolution from select coastal tracts of Northern Tuscany by inspecting their internal sedimentary architecture with Ground-Penetrating Radar (GPR) analysis. Erosion, equilibrium and accretion characterize the selected coastal tracts, and this analysis remarks on some GPR features consistently associated with specific coastal evolution states. A standard sequence of data processing made it possible to trace several radar surfaces and reflectors in the GPR profile, eventually interpreted in terms of depositional processes and erosive events. The stable or currently accreting coastal sectors show radar features compatible with a general beach progradation process, punctuated by berm formation in the general context of a positive sedimentary budget. Additionally, the radar facies distribution locally supports a mechanism of dune nucleation on an abandoned berm. Conversely, the GPR profile of the coastal sector today affected by erosion shows how a negative sedimentary budget inhibited coastal progradation and favored destructive events. These events interacted also with the active dunes, as demonstrated by the overlapping of wave run-up and aeolian radar facies. GPR prospections were effective at delineating the recent/ongoing coastal sedimentary budget by identifying radar features linked to construction/destruction phenomena in the backshore, and to dune nucleation/evolution. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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17 pages, 5606 KiB

Open AccessArticle

Four-Dimensional Investigation of Gravel Beach Ridge Accretion and 50 Years of Beach Recharge at Dungeness, UK, Using Historic Images, GPR and Lidar (HIGL)

by Charlie S. Bristow, Lucy Buck and Maria Inggrid

Appl. Sci. 2021, 11(21), 10219; https://doi.org/10.3390/app112110219 - 01 Nov 2021

Viewed by 2195

Abstract

Dungeness is a cuspate foreland on the south coast of England that is the largest shingle feature in Europe and includes hundreds of beach ridges. It is also the location of two nuclear power stations that were constructed in the 1960s. The dominant [...] Read more.

Dungeness is a cuspate foreland on the south coast of England that is the largest shingle feature in Europe and includes hundreds of beach ridges. It is also the location of two nuclear power stations that were constructed in the 1960s. The dominant southwest waves cause longshore drift from west to east, eroding the southwest side of Dungeness, accompanied by accretion on the east side. A record of this eastward movement and sediment accretion is preserved by the shingle beach ridges. The power stations are located on the eroding southwestern side of the ness, and a system of beach recharge has been used to move shingle from the downdrift, east-facing shore to the updrift, southwest-facing shore to protect the power stations from coastal erosion. We use a novel combination of historic images, ground-penetrating radar (GPR), and Lidar (HIGL) to investigate accretion and beach ridges at Dungeness during the past 80 years. We report changes in accretion along the coast and use GPR to determine the thickness of beach gravels. The amount of accretion, represented by the width of the backshore, decreases downdrift from south to north. The number of beach ridges preserved also decreases from south to north. By combining the shingle thickness from GPR with elevation data from Lidar surveys and records of beach accretion measured from aerial images, we estimate the volume and mass of gravel that has accumulated at Dungeness. Historic rates of beach accretion are similar to recent rates, suggesting that the 55 years of beach recharge have had little impact on the longer-term accretion downdrift. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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18 pages, 22654 KiB

Open AccessArticle

Optimised Extraction of Archaeological Features from Full 3-D GPR Data

by Emanuele Forte, Arianna Mocnik, Patrizia Basso, Giulia Casagrande, Davide Martinucci, Simone Pillon, Marco Possamai and Roberta Zambrini

Appl. Sci. 2021, 11(18), 8517; https://doi.org/10.3390/app11188517 - 14 Sep 2021

Cited by 8 | Viewed by 1841

Abstract

The use of non-invasive methodologies is becoming essential for archaeological research, and ground penetrating radar is one of the most important techniques to obtain high resolution information. In this paper we present the analysis of a full 3-D GPR dataset integrated with a [...] Read more.

The use of non-invasive methodologies is becoming essential for archaeological research, and ground penetrating radar is one of the most important techniques to obtain high resolution information. In this paper we present the analysis of a full 3-D GPR dataset integrated with a high-resolution photogrammetric survey acquired in a Roman archaeological site located in Aquileia (Northeast Italy) within the partially excavated area known as “Fondo Pasqualis”. We evaluated the importance of dense and accurate data collection and of processing of the GPR signal for characterization of the archaeological features. We further discuss the parametrization and the applicability of GPR attributes, in particular amplitude-based and coherence attributes, to better identify and characterise the archaeological buried targets. Furthermore, autopicking procedures for isosurfaces mapping were critically evaluated with the objective of detecting complex structures. The final interpretation of all the GPR features, with the support of digital terrain modelling and orthophotos from unmanned aerial vehicles, guided the archaeologists to open and excavate newly selected areas, which revealed interesting structures and contributed to the understanding of the historical events that characterized the Aquileia city. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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9 pages, 11843 KiB

Open AccessArticle

Ground-Penetrating Radar Imaging of Near-Surface Deformation along the Songino Active Fault in the Vicinity of Ulaanbaatar, Mongolia

by Maksim Bano, Nyambayar Tsend-Ayush, Antoine Schlupp and Ulziibat Munkhuu

Appl. Sci. 2021, 11(17), 8242; https://doi.org/10.3390/app11178242 - 06 Sep 2021

Cited by 8 | Viewed by 1829

Abstract

The seismic activity observed in the vicinity of Ulaanbaatar (UB) capital city has been increased since 2005. Several active faults have been identified in the UB area. Most of the Mongolian population is concentrated around UB (1.5 million), which is the main political [...] Read more.

The seismic activity observed in the vicinity of Ulaanbaatar (UB) capital city has been increased since 2005. Several active faults have been identified in the UB area. Most of the Mongolian population is concentrated around UB (1.5 million), which is the main political and economic center of the country. Hence, the study of seismic hazard is of first importance for the country. In this paper, we present the GPR results obtained on the Songino fault which is situated at 20 km west-southwest of UB at the northeast tip of Khustai fault. The combination of the morphotectonic, GPR and paleoseismological investigations brings essential information for seismic hazards assessments. The 2D GPR profiles are measured by using 250 and 500 MHz antennae and the topography using a differential GPS. An appropriate processing of the GPR data, including the topographic migration, allows us to bring out indirect characteristics of these faults. The objective is to identify near-surface geometry and coseismic deformation along the mapped fault. The 250 MHz GPR images of the Songino fault show the evolution of the sub-surface deformation mode induced by the arched geometry of the Songino fault. We observe a clear compressive structure at its NW section, strike slip at its central section and extensive structure in its SE part. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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12 pages, 7091 KiB

Open AccessFeature PaperArticle

Integrating Airborne Laser Scanning and 3D Ground-Penetrating Radar for the Investigation of Protohistoric Structures in Croatian Istria

by Federico Bernardini, Giacomo Vinci, Emanuele Forte, Arianna Mocnik, Josip Višnjić and Michele Pipan

Appl. Sci. 2021, 11(17), 8166; https://doi.org/10.3390/app11178166 - 03 Sep 2021

Cited by 6 | Viewed by 2014

Abstract

We present the investigation of two rather ephemeral archaeological sites located in the municipality of Oprtalj/Portole (Croatian Istria) by means of integrated archaeological, geophysical and remote sensing techniques. The results obtained confirm the first interpretation of these contexts; a protohistoric burial mound and [...] Read more.

We present the investigation of two rather ephemeral archaeological sites located in the municipality of Oprtalj/Portole (Croatian Istria) by means of integrated archaeological, geophysical and remote sensing techniques. The results obtained confirm the first interpretation of these contexts; a protohistoric burial mound and a small hillfort, respectively. We further obtained detailed information about both deposits through 2D and 3D remote sensing and geophysical studies that produced maps, volumes, profiles and cross-sections. At the first site, the volume reconstruction of both the inner stone core and the superimposed earth of the putative stone mound also allowed us to estimate the labour necessary to erect the structure. In conclusion, our study demonstrates that the integrated approach can be valuable not only to acquire novel data about the archaeological deposits but also to calibrate future investigations and to plan effective measures for heritage management, monitoring and valorization. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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12 pages, 27407 KiB

Open AccessArticle

Delineation of Fractures Using a 2D GPR Processing Strategy for 3D Imaging: Weak Zones within Carbonates at the Archaeological Site of Xochicalco in Mexico

by Nikos Economou, Maksim Bano and José Ortega-Ramirez

Appl. Sci. 2021, 11(13), 5893; https://doi.org/10.3390/app11135893 - 24 Jun 2021

Cited by 3 | Viewed by 1500

Abstract

The use of GPR data multipath summation on data acquired over parallel study lines is presented here within the framework of a study on the effects of natural hazards on cultural heritage areas in order to image weak zones within carbonates, such as [...] Read more.

The use of GPR data multipath summation on data acquired over parallel study lines is presented here within the framework of a study on the effects of natural hazards on cultural heritage areas in order to image weak zones within carbonates, such as fractures and caverns. This study was realized at the archeological site of Xochicalco in Mexico, where fractures and caverns are potential sources of the degradation of the archeological remains. Dense parallel GPR study lines spaced every 0.25 m were surveyed using a 400 MHz monostatic antenna with the aim to image possible weak zones in three dimensions. We used a 2D imaging approach, namely, the method of multipath summation, which efficiently focused the scattered energy within the GPR sections. The study revealed, at depths of 1.6m and 1.8m, several linear events attributed to fractures, leading to the preliminary conclusion of this on-going project that cracks on the walls of the Quetzalcoatl Temple after a large earthquake in 2017 are prone to instability of carbonates rocks. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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Review

Jump to: Research

12 pages, 1956 KiB

Open AccessReview

GPR Data Interpretation Approaches in Archaeological Prospection

by Merope Manataki, Antonis Vafidis and Apostolos Sarris

Appl. Sci. 2021, 11(16), 7531; https://doi.org/10.3390/app11167531 - 17 Aug 2021

Cited by 12 | Viewed by 2529

Abstract

This article focuses on the possible drawbacks and pitfalls in the GPR data interpretation process commonly followed by most GPR practitioners in archaeological prospection. Standard processing techniques aim to remove some noise, enhance reflections of the subsurface. Next, one has to calculate the [...] Read more.

This article focuses on the possible drawbacks and pitfalls in the GPR data interpretation process commonly followed by most GPR practitioners in archaeological prospection. Standard processing techniques aim to remove some noise, enhance reflections of the subsurface. Next, one has to calculate the instantaneous envelope and produce C-scans which are 2D amplitude maps showing high reflectivity surfaces. These amplitude maps are mainly used for data interpretation and provide a good insight into the subsurface but cannot fully describe it. The main limitations are discussed while studies aiming to overcome them are reviewed. These studies involve integrated interpretation approaches using both B-scans and C-scans, attribute analysis, fusion approaches, and recent attempts to automatically interpret C-scans using Deep Learning (DL) algorithms. To contribute to the automatic interpretation of GPR data using DL, an application of Convolutional Neural Networks (CNNs) to classify GPR data is also presented and discussed. Full article

(This article belongs to the Special Issue Applications of Ground-Penetrating Radar to Geomorphology, Near-Surface Geology and Geoarchaeology)

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