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NSG2021 2nd Conference on Geophysics for Infrastructure Planning, Monitoring and BIM
- Conference date: August 29 - September 2, 2021
- Location: Bordeaux, France / Online
- Published: 29 August 2021
1 - 20 of 36 results
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Geological Reconstruction by 2D-ERT of the Maddaloni-Durazzano Ridge (Italy) for a Railway Line Design
Authors C. Fabozzi, S. Vitale, C. De Paola, S. Ciarcia and R. Di MaioSummaryWe present a geophysical study for the executive project of a railway tunnel across the Maddaloni-Durazzano carbonate ridge (southern Italy). To reconstruct the geological setting of the area, a N-S oriented electrical resistivity tomography (ERT) profile, about 4 km long, was performed, which allowed an exploration depth of about 200 m from the surface level. The results of the 2D inversion model of the ERT profile clearly highlight anomalous resistive blocks that can be associated with fractured/karst sectors of the Cretaceous carbonate succession affected by significant water circulation, while there are no evident resistivity anomaly features linked to the presence of large cavities. Significantly, the geophysical model identifies at the northern end of the ERT profile, where the entrance to the tunnel was planned, the presence of the regional thrust fault bounding the northern side of the ridge, which was hypothesized by the geological cartography but not supported by field observations. The validation of the geological-structural model provided by the ERT interpretation was derived from geognostic boreholes and direct observations carried out during the excavation of a tunnel crosscutting the ERT section.
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GPR and NDT Surveys on a Proposed UK Spaceport Runway
Authors J. Eason, A. Verweerd and W. AndrewsSummaryWe present a case study of a runway construction assessment utilizing ground penetrating radar, heavy weight deflectometry and intrusive data for a proposed horizontal launch spaceport in the United Kingdom. The presentation will showcase an integrated approach of non-destructive and intrusive elements on an existing runway to assess planned use and potential requirements for upgrade the existing infrastructure for new purposes.
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Experimental Study to Characterize a Magneto-Functional Technology vs. Corrosion in Reinforced Concrete Structures
Authors D. Souriou, A. Ihamouten, S. Kadkhodazadeh, B. Fan and D. GuilbertSummaryIn this paper, we propose to show the results of an experimental study to validate a concept of a new Structure Health Monitoring (SHM) sensor dedicated to the detection of aggressive agents in reinforced concrete structures. This sensor, aimed to be embedded in cover concrete, is composed with a permanent part, that acts as a reference magnetic source, coupled with a magneto-functional material (or reactive part), directly in touch with aggressive agents (chlorides in our case) that can cause its corrosion. As a function of its corrosion rate, the reactive part can filter differently a magnetic non destructive observable measured from the permanent part. We chose to present measurements of the magnetic non destructive observable of sensors with reactive parts in their initial and corroded states. The influence of reactive part’s thickness and corrosion rate (based on relative mass loss of reactive part) are shown. Variations of the magnetic observable can be correlated with mass loss of reactive part. These results allowed to draw a empirical calibration curves providing a possibility to monitor reactive part’s corrosion rate. These informations could be used to detect the presence of aggressive agents before they reach rebars.
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Electrical imaging of the slip geometry of a deep-seated landslide (Canelles Dam, NE Spain)
Authors A. Sendrós, M. Himi, C. Abancó, R. Lovera, L. Rivero, A. Urruela, R. Garcia-Artigas and A. CasasSummaryThe occurrence of large landslides in the slopes of reservoirs may produce a reduction of the water storage capacity and generate water waves which could cause catastrophic flooding if the dam crest is overtopped or breached. The massive and catastrophic rockslide of Vajont reservoir that occurred in 1963 demonstrated the importance of performing detailed geological, geomorphological, hydrogeological and geotechnical investigations in rock masses and soil slopes. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological changes that has demonstrated useful to provide the detailed subsurface information required to improve the diagnosis of the slope stability and finding the most suitable zones to fail. The relationships between the electrical resistivity of the high and low-bearing capacity sediments identified in Canelles site highlight the potential of geoelectical methods over other more costly subsurface exploration techniques. The proposed approach show potential to be applied coupled to numerical models to define the boundary conditions up to 100 meters depth with a 5–10 meters resolution and could also help to optimize the required borehole research and monitoring campaign in the initial research stages of landslide characterization.
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High-resolution assessment of road basement using ground-penetrating radar (GPR)
Authors A. Sendrós, A. Casas, C. Abancó, L. Rivero, R. Garcia-Artigas, A. Urruela, R. Lovera and M. HimiSummaryRoad networks suffer significant structural damage caused by a variety of reasons amplified if the underlying geology induces cracks or deformations. The most common procedure to obtain information from the interior layers of the infrastructure is drilling holes in the road. However, these diagnostic tools are destructive, expensive and slow. Ground Penetration Radar (GPR) brings considerable advantages for the detection of pathologies in inner layers of the road, such as cracks in the wearing course, buried holes and settlement problems providing high-quality images of the radar signal in the interior of the structures. The objectives of the research were to carry out a study with the GPR technique of degraded road pavements to delineate the lateral and depth extent of the cracks and to identify the most problematic areas of the 1 km studied segment. The use of the GPR methods in Pont de Suert site (Spain) have provided an accurate road conditions assessment and differentiate areas with very clear anomalies, that were not visible from the surface, which can serve as a guide for the road managers to intervene before the collapse due to dissolution of gypsums sediments would occur
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Terrestrial CSEM for buried steel infrastructure
Authors M. S. Hickey, S. Trevino III and M. EverettSummaryMaintenance of buried steel infrastructure is an important problem in civil engineering practice. Corrosion, for example, can lead to damage and excessive repair or replacement expenses. Soil corrosivity is one of the main physical factors that determines the corrosion rate of pipelines and other steel infrastructure. Methods that can reliably estimate soil corrosivity by non-invasive and inexpensive means would be of great benefit to the civil engineering community. Soil corrosivity is well-known to depend on multiple interacting physical factors such as moisture content, aeration, pH, organic matter content, microbial activity, etc. However, in most cases a dry and/or sand-dominated soil is electrically resistive and generally less corrosive in comparison with a wet and/or clay-dominated soil characterized by lower bulk resistivity. In this paper, with the objective of evaluating terrestrial CSEM as a potential tool for mapping possible corrosion of buried steel infrastructure, we examine synthetic responses from a terrestrial CSEM layout and report the magnitudes and characteristics of secondary signals that are caused by the presence of a zone of anomalous soil resistivity surrounding a uniform steel pipe. Further consideration of development of a practical slingram-type terrestrial CSEM system for steel infrastructure investigation is recommended.
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Numerical modeling using gprMax to identify a subsurface tack coat for SVM classification
Authors G. Andreoli, A. Ihamouten, C. Fauchard, R. Jaufer, S.S. Todkar, D. Guilbert, V. Buliuk and X. DérobertSummaryFace to an increasing traffic volumes, a poor adhesion between bitumen layers combined with weather conditions can lead to premature deterioration of pavement structures. Therefore, it is essential to resort a tack coat where the wearing course and the binder course connect, so that they work as a monolithic block. The purpose of this study, carried out by using gprMax software, is to identify a thin millimetric subsurface tack coat from a modelled bilayer of bitumen and to differentiate the signals according to the modifications of some parameters like thickness, permittivity and conductivity. The so generated large database of time signals with diverse geometric and dielectric characteristics will enable to classify the datas by a supervised machine learning method namely, Support Vector Machines (SVM). Among existing methods, the algorithm of Two-Class SVM (TCSVM) allows to split the datas in two distinct classes. One data set is described as the “adhered” class, and another as the “non adhered” class. The supervised machine learning is conducted with a resolution by global approach to use the raw data set, without any pre-processing. Finally, the binary classification appears then as a promising method to identify clearly and automatically the presence of a tack coat.
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Geophysical survey in the frame of preservation works for an old silo of planes
Authors G. Apostolopoulos, S. Karizonis, G. Amolochitis and D. KaraiskosSummaryA geophysical survey was carried out for the detection of anthropogenic constructions under the floor of an old silo of planes made in 1938 in the area of the Old Airport of Elliniko in the frame of its preservation works. GPR and FEM measurements gave GPR sections, 3D presentation of processed GPR data and in-phase component maps that detected various anthropogenic features and information for the foundation of the building.
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Dielectric relaxation of iron corrosion products in limestone under saline environment
Authors B. Fan, D. Souriou, F. Bosc, D. Guilbert, S. Kadkhodazadeh, A. Ihamouten, C. Fauchard and X. DérobertSummaryLimestone is selected as test material because of its easy accessibility, adaptation for the dielectric measurement, and high porosity (45–55%) that quickens the observation of the corrosion diffusion. The corrosion process is launched by an iron plate on the surface of the limestone imbibed in a saline solution. The complex dielectric properties from 50 MHz to 1.5 GHz have been measured for samples with and without iron plate since most of GPR applications cover this frequency band in NDE. To analyse the dielectric relaxions associated with the corrosion products (mainly Fe rust, Fe2O3), the electrical module has been used as a main analysis tool to suppress the influence of an apparent direct current conductivity (σdc) brought by the imbibition saline liquid. By finding out the feature relaxation peak of the Fe rust at a certain frequency, the content of Fe rust in the whole limestone can be estimated by the application of the complex refractive index model (CRIM). We hope that this study on the dielectric relaxation of Fe rust in limestone under saline environment can be served as a model which can eventually adapt for concrete structures in our future works.
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Seismic Modelling for Monitoring of Historical Quay Walls and Detection of Failure Mechanisms
Authors F. Balestrini, D. Draganov, M. Staring, J. Singer, J. Heijmans and P. KaramitopoulosSummaryMonitoring of historic quay walls is key for the early identification of damages that can lead to the failure and collapse of these structures. Currently used methodologies focus on the detection of deformations by high-resolution mapping of the surface of the constructions. Since the collapse of historic quay walls is usually a consequence of internal failure, we analyse the feasibility of utilising seismic methods for imaging the inner structure of quay walls to assess their current state. For this work, we propose to deploy seismic equipment in the water of the canal from a sailing boat to assess and monitor the construction in land. We perform numerical modelling to simulate data for possible scenarios with different acquisition configurations. Our results suggest that seismic methods are practical and viable for the assessment and monitoring of historical quay walls. We show that the overall structure can be imaged, and potential failure mechanism can be promptly identified. Information about the shallow soil structure can also be retrieved. We expect that this method can help the detection of failure mechanisms at an early stage.
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Operational Use Cases Using Resqml Standard to Communicate Geotechnics and Subsurface Information to Bim
Authors V. GAUTHIER, P. LABOURG, J. LEONARD and J. RAINAUDSummaryThe aim of this presentation in four parts is to present how the RESQML format previously designed to exchange between Geosciences applications can be used in the Geotechnical domain by a BIM (Building Information Modeling) software to receive a global consistent image of the subsoil combining Geology, Geotechnics and DTM (Digital Terrain Modeling).
We present the main RESQML principles, explain how the RESQML format (www.energistics.org) handle semantically the subsurface information, and demonstrate how EGIS GROUP, an Environmental and Infrastructure Company, was setting up a software environment with the help of a Geoscience expert to communicate subsoil information to a BIM oriented software (CIVIL 3D from Autodesk). Then, we show on several Use cases how the information is finally integrated in a BIM environment to be used by operational teams.
These use cases were realized by RESQML CAD, A plug-in for Autodesk Civil 3D, developed in C#.NET under Visual Studio in collaboration between EGIS and GEOSIRIS. This tool is providing Geotechnical information as horizons and faults of the 3D models, drawing boreholes in 3D, drawing fence-diagrams and 3D logs data to this BIM software. Each drawn element is also associated to a list of attributes in a BIM database
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Use of Deep Lerning on GPR data for parameter inversion of buried cylindrical pipes
Authors R. Jaufer, A. Ihamouten, S. Savant Todkar, F. Bosc, Y. Goyat and X. DérobertSummaryGround Penetrating Radar (GPR) has become one of the popular Non-Destructive Testing (NDT) methods in the field of Geophysics and civil engineering applications. In this context, for applications like concrete rebars assessments, utility networks surveys, the precise localization of embedded cylindrical pipes remains still challenging due to complex geometrical and dielectric characteristics of the stratified medium. In recent years, several hyperbola-centric machines learning based novel techniques have been introduced to accomplish localization of cylindrical objects from the GPR data.
In this paper, performance of Multi-layer perceptron (MLP) based Artificial Neural Networks (ANN) model combined with six statistical travel time features extracted from hyperbola were studied. The model is used to predict the velocity of the stratified medium, depth of cylindrical pipe and radius of the pipe. The approach is based on hyperbola traces emerging from a set of B-scans, whereas the shape of hyperbola highly varies with depth and radius of the pipe as well as the velocity of the medium. Hence, Finite-Difference Time-Domain (FDTD) based 2D numerical tool namely GprMax is used to simulate GPR data. A parametric comparison is also included in the performance analysis of the techniques in terms of relative error estimations against designed parameters.
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Geophysical Remote Condition Monitoring of Transportation Infrastructure Slopes
Authors J. Chambers, P. Meldrum, P. Wilkinson, D. Gunn, A. Watlet, B. Dashwood, J. Whiteley, H. Harrison, R. Swift, C. Inauen, O. Kuras, G. Jessamy, S. Glendinning, P. Clarkson, C. Minto, A. Godfrey and R. CrickmoreSummaryHere we consider the development and use of geophysical remote-condition-monitoring (RCM) solutions for monitoring slope stability, which have the advantage of providing spatial and volumetric subsurface information with the potential to identify the causal processes leading to slope failure. We illustrate geophysical RCM of transportation infrastructure and third party land, with examples from highways and rail, and with reference to the Hollin Hill Landslide Observatory (HHLO), which has been used to trial candidate technologies, to show the benefit of integrated geophysical-geotechnical monitoring approaches.
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Optimized joint interpretation of many different datasets using BIM methodology combining CoClass and GeoBIM
Authors M. Svensson and O. FribergSummaryIn any project careful data management is one of the core issues, certainly in long on-going projects. In projects trying to understand the contamination situation the number of different datasets is often large and of many different data types. On a former gasworks facility in a railway yard, in Bräcke in Sweden, many different methods were used, aiming at understanding the spread of primarily tar and PAH contaminants. Some of the methods were geotechnical sounding and sampling, chemical laboratory tests and DCIP. From the start a BIM methodology was chosen to ensure good order of the data also in the longer perspective. The GeoBIM tool was used for data management and for visualization of both data and geomodels using only a web browser, allowing all involved stakeholders to get access to the same information. For allowing not only visual joint interpretation but also automated and advanced comparisons and analyses of the whole data set all data was classified in the CoClass system. CoClass is a hierarchical system allowing computers to sort and analyze data according to a standardized system. The BIM approach applying CoClass on the data managed by the GeoBIM concept clearly improved the ability of analyzing the data.
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Geophysical investigation of failure on a railway cutting
Authors A. Verweerd, W. Andrews and J. EasonSummaryA case study about a geophysical investigation on the rockface of a railway cutting in Wales (UK). A fissure was observed at the surface above the cutting, with the risk of collapse of the rockface on the railway line. A standard ERT and GPR survey was executed, interpreted in a novel way by incorporating full 3D topographic data capture and visualization. The resulting dataset was interpreted to assess the depth of the fissure and associated risk of collapse which will be used in development of a remediation scheme of the site to allow normal railway operations to resume.
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Multi-disciplinary geophysical investigation to identify road failure mechanism
Authors A. Verweerd and J. GomerySummaryCase study investigation failure mechanism of a road in Derbyshire (UK). The road is located on a ridge, with steep slopes on either side as well as known historical mineworkings in close vicinity. A multi-disciplinary geophysical survey was executed to identify the potential failure mechanism after cracks in the road surface were observed. The combined interpretation of all techniques provided a detailed image of the subsurface allowing identification of the most likely failure mechanism, which will be used in design of a remediation strategy.
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Test Range For UAV-Based Geophysical Sensors
Authors A. Dobrovolskiy and K. LinkevičsSummaryThe idea of using UAV (unmanned area vehicles, drones) to carry appropriate sensors to locate underground objects and utilities seems obvious. However, industry players lack strong experience and knowledge about the capabilities of airborne sensors, or information about the limitations of sensors combining with UAV. Another important point is the methodological aspects of airborne sensors application — how to plan UAV flights, data processing, expected precision of localization, etc. To fill the gaps, we at SPH Engineering built a test range with buried utilities (pipes) of different diameter, material and depth, as well as other objects, and conducted extensive tests of different available sensors over known targets.
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Sharing Geophysical Data for Seismic Characterization of the Matera (Southern Italy) Urban Area
Authors N. Tragni, G. Calamita, L. Lastilla, V. Belloni, R. Ravanelli, M. Lupo, V. Salvia and M.R. GallipoliSummaryIn the Smart Cities perspective, the digital archiving of all geological, geotechnical, geophysical and engineering data of cities should become a useful tool to plan strategies for seismic risk mitigation in terms of urban planning, seismic retrofitting, and management of post-earthquake crises. The CLARA WebGIS geodatabase, developed and released in the framework of CLARA project (CLoud plAtform and smart underground imaging for natural Risk Assessment) move toward this way; it contains 488 georeferenced and downloadable surveys (such as Downholes, Mechanical Surveys, Salcarenite Sampling Stations, MASW, HVNSR, Seismic Refraction Surveys), the geological and geomorphological maps and map of homogeneous microzones from a seismic response perspective and 215 new single-station seismic ambient noise measurements carried out on urban soils and buildings. CLARA WebGIS is the first publicly available database reporting for the whole urban area the spatial distribution of the soil resonance frequencies and the vibrational frequency of the overlying 4043 buildings, along with the probability of soil-building resonance occurrence. All data are accessible, visualizing, querying and downloadable at this link: https://smartcities-matera-clara.imaa.cnr.it/
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Combination of Passive and Active Methods Towards Site Characterization of Accelerometer Stations in Greece
Authors G. Papadopoulos, I. Fikos, A. Garcia-Jerez, N. Theodoulidis and G. VargemezisSummaryThe present work deals with the inversion of HVSR. curves to obtain shear wave velocity profiles and how a priori information could be incorporated to facilitate the H/V inversion procedure. The inversion is conducted using the “HV-Inv” computer code (Garcia-Jerez et al., 2016), which is based on the Diffuse Field Assumption and uses the relation between the HVSR and the elastodynamic Green’s function. This code is packed with 3 global (Monte Carlo sampling, Simulated Annealing and Modified Simulated Annealing) and 2 local (Simplex Downhill, Interior Point) inversion methods. Three test groups with different properties and with all 5 inversions methods are examined to test various capabilities of the software. A final test is conducted using the experience of the previous ones, achieving inversions with lower misfit.
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Fast Near-Surface Investigation With Surface-Wave Attributes
Authors M. Papadopoulou, C. Colombero, M. Staring, J. Singer, R. Eddies, M. Fliedner, F. Janod and V. SoccoSummaryFast methods for site characterization and imaging of potentially problematic zones, such as voids and discontinuities, are valuable in geotechnical engineering, to manage risks and meet business objectives. We present a nearly real-time screening tool which uses seismic surface-wave attributes (phase velocity and energy) to produce quantitative indication of lithological variations and other shallow targets. We present the results from an engineering experiment and compare them with a priori information on the site.
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