Towards Long-Term Monitoring of the Structural Health of Deep Rock Tunnels with Remote Sensing Techniques

Due to the substantial need to continuously ensure safe excavations and sustainable operation of deep engineering structures, structural health monitoring based on remote sensing techniques has become a prominent research topic in this field. Indeed, throughout their lifetime, deep tunnels are usually exposed to many complex situations which inevitably affect their structural health. Therefore, appropriate and effective monitoring systems are required to provide real-time information that can be used as a true basis for efficient and timely decision-making. Since sensors are at the heart of any monitoring system, their selection and conception for deep rock tunnels necessitates special attention. This work identifies and describes relevant structural health problems of deep rock tunnels and the applicability of sensors employed in monitoring systems, based on in-depth searches performed on pertinent research. The outcomes and challenges of monitoring are discussed as well. Results show that over time, deep rock tunnels suffer several typical structural diseases namely degradation of the excavation damaged areas, corrosion of rock bolts and cable bolts, cracks, fractures and strains in secondary lining, groundwater leaks in secondary lining, convergence deformation and damage provoked by the triggering of fires. Various types of remote sensors are deployed to monitor such diseases. For deep rock tunnels, it is suggested to adopt comprehensive monitoring systems with adaptive and robust sensors for their reliable and long-lasting performance

Development of optical fibre distributed sensing for the structural health monitoring of bridges and large scale structures

Tesi per compendi de publicacionsPremi extraordinari doctorat UPC curs 2017-2018. Àmbit d’Enginyeria Civil i AmbientalIn this doctoral thesis it is proposed to research and assess the performance of the use of distributed optical fiber sensors (DOFS), more specifically the case of the optical backscattered reflectometry (OBR) based system, to the structural health monitoring (SHM) of bridges and large scale structures. This is a relatively recent technology that has demonstrated great promise for monitoring applications in a wide range of fields but due to its novelty, still presents several uncertainties which prevent its use in a more systematic and efficient way in civil engineering infrastructures. This is even more evident and relevant in the case of the application of this sensing technique to concrete structures. In this way, this thesis pretends to continue and further analyse this topic following the initial applications using the OBR system as a possible alternative/complementary monitoring tool in concrete structures. Therefore, in the present thesis, after an initial and thorough literature review on the use of DOFS in civil engineering applications, a set of experiments and analysis is planned and carried out. Firstly, different laboratory experimental campaigns are devised where multiple aspects of the instrumentation of DOFS technology in civil engineering applications are assessed and scrutinized. Consequently, the study of new implementation methods, comparison and performance analysis of different bonding adhesives and spatial resolution is performed through the conduction of load tests in reinforced concrete beam elements instrumented with OBR DOFS technology. Moreover, the long-term reliability of this sensing typology is also assessed through the conduction of a fatigue load test on two additional reinforced concrete beams. Afterwards, the use of the OBR system technology is assessed for the application in two real world structures in Barcelona, Spain. The first application corresponds to a previous monitoring work conducted in a historical masonry building and UNESCO World Heritage Site, which was subjected to rehabilitation works and where the collected data was analysed and interpreted in this thesis. The second real world structure application is an urban prestressed concrete viaduct that was exposed to major renovation actions, which included the widening of its deck and the introduction of new steel elements on the improved pedestrian sidewalks. This second application was conducted through a relatively extended period of time, which spanned from early summer to deep winter and therefore causing subsequent important thermal variations effects implications on the performance of the instrumented OBR system leading to the necessity of its compensation. Finally, taking into account the previous points, several conclusions are obtained related with the proficiency and limitations on the use of this particular type of optical sensing system in concrete structures. The advantages and disadvantages on the use of different types of bonding adhesives, implementation methodologies and spatial resolutions are described. Additionally, the performance of this technology in real world conditions is studied and characterized.En aquesta tesi doctoral es proposa investigar i avaluar la possibilitat d´aplicació de sensors de fibra òptica distribuïda (DOFS), més concretament un sistema del tipus OBR (Optical Backscattered Reflectometry), a la monitorització de la salut estructural (SHM) de ponts i estructures de grans dimensions. Es tracta d'una tecnologia relativament recent que ha demostrat una gran versatilitat i validesa en diferents aplicacions en un ampli ventall de camps, però que, a causa de la seva novetat, encara presenta diverses incerteses que impedeixen el seu ús d'una manera més sistemàtica i eficient en el cas de les infraestructures d'enginyeria civil. Sent això especialment cert i rellevant en el cas de l'aplicació d'aquesta tipologia de detecció en estructures de formigó. D'aquesta manera, aquesta tesi pretén continuar i analitzar aquest tema seguint les aplicacions inicials utilitzant el sistema OBR com una possible eina i de control alternatiu o complementari en estructures de formigó. Per tant, en aquesta tesi, després d'una revisió inicial i exhaustiva de la literatura sobre l'ús de DOFS en aplicacions d'enginyeria civil, es planifiquen i executen un conjunt d'assaigs experimentals i el seu posterior anàlisi. En primer lloc, es desenvolupen diferents campanyes experimentals de laboratori on s'avaluen i examinen múltiples aspectes de la tecnologia DOFS en aplicacions d'enginyeria civil. Com a conseqüència, s´estudien nous mètodes d'implementació, de comparació i anàlisi de rendiment de diferents adhesius de connexió i de resolució espaial mitjançant la realització de proves experimentals en elements a flexió a de formigó armat equipats amb tecnologia OBR DOFS. A més, la fiabilitat a llarg termini d'aquesta tipologia de sensors també s'avalua mitjançant la realització d'un assaig de fatiga en dos bigues de formigó armat addicionals. Posteriorment, l'ús de la tecnologia del sistema OBR s'avalua de cara a la seva aplicació en dues estructures reals a Barcelona, Espanya. La primera aplicació correspon a un treball de seguiment previ dut a terme en un edifici històric de maçoneria i que és Patrimoni de la Humanitat de la UNESCO (l´hospital de Sant Pau), que es va sotmetre a obres de rehabilitació i on es van analitzar i interpretar les dades recollides durant l´execució de les obres. La segona aplicació és un pont de formigó pretensat urbà que va estar exposat a una important intervenció de renovació, que va incloure l'ampliació de la coberta i la introducció de nous elements d'acer a les voreres de vianants. Aquesta segona aplicació es va dur a terme a través d'un període de temps relativament estès, que va des del començament de l'estiu fins a ben entrat l'hivern i, per tant, va provocar variacions tèrmiques importants tant als materials com als propis sensors, que van tenir conseqüències sobre el rendiment del sistema OBR instrumentat i que va comportar la necessitat de la seva compensació. Finalment, tenint en compte els punts anteriors, s'obtenen diverses conclusions relacionades amb la competència i les limitacions sobre l'ús d'aquest tipus particular de sistema de detecció òptica en estructures de formigó. Es descriuen els avantatges i desavantatges sobre l'ús de diferents tipus d'adhesius de connexió, metodologies d'implementació i resolucions espaials. Addicionalment, s'estudia i caracteritza l'acompliment d'aquesta tecnologia en condicions reals i no de laboratori.Award-winningPostprint (published version

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Towards Long-Term Monitoring of the Structural Health of Deep Rock Tunnels with Remote Sensing Techniques

Due to the substantial need to continuously ensure safe excavations and sustainable operation of deep engineering structures, structural health monitoring based on remote sensing techniques has become a prominent research topic in this field. Indeed, throughout their lifetime, deep tunnels are usually exposed to many complex situations which inevitably affect their structural health. Therefore, appropriate and effective monitoring systems are required to provide real-time information that can be used as a true basis for efficient and timely decision-making. Since sensors are at the heart of any monitoring system, their selection and conception for deep rock tunnels necessitates special attention. This work identifies and describes relevant structural health problems of deep rock tunnels and the applicability of sensors employed in monitoring systems, based on in-depth searches performed on pertinent research. The outcomes and challenges of monitoring are discussed as well. Results show that over time, deep rock tunnels suffer several typical structural diseases namely degradation of the excavation damaged areas, corrosion of rock bolts and cable bolts, cracks, fractures and strains in secondary lining, groundwater leaks in secondary lining, convergence deformation and damage provoked by the triggering of fires. Various types of remote sensors are deployed to monitor such diseases. For deep rock tunnels, it is suggested to adopt comprehensive monitoring systems with adaptive and robust sensors for their reliable and long-lasting performance

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Contemporary Inspection and Monitoring for High-Speed Rail System

Non-destructive testing (NDT) techniques have been explored and extensively utilised to help maintaining safety operation and improving ride comfort of the rail system. As an ascension of NDT techniques, the structural health monitoring (SHM) brings a new era of real-time condition assessment of rail system without interrupting train service, which is significantly meaningful to high-speed rail (HSR). This chapter first gives a review of NDT techniques of wheels and rails, followed by the recent applications of SHM on HSR enabled by a combination of advanced sensing technologies using optical fibre, piezoelectric and other smart sensors for on-board and online monitoring of the railway system from vehicles to rail infrastructure. An introduction of research frontier and development direction of SHM on HSR is provided subsequently concerning both sensing accuracy and efficiency, through cutting-edge data-driven analytic studies embracing such as wireless sensing and compressive sensing, which answer for the big data’s call brought by the new age of this transport

Machine learning algorithms for monitoring pavement performance

ABSTRACT: This work introduces the need to develop competitive, low-cost and applicable technologies to real roads to detect the asphalt condition by means of Machine Learning (ML) algorithms. Specifically, the most recent studies are described according to the data collection methods: images, ground penetrating radar (GPR), laser and optic fiber. The main models that are presented for such state-of-the-art studies are Support Vector Machine, Random Forest, Naïve Bayes, Artificial neural networks or Convolutional Neural Networks. For these analyses, the methodology, type of problem, data source, computational resources, discussion and future research are highlighted. Open data sources, programming frameworks, model comparisons and data collection technologies are illustrated to allow the research community to initiate future investigation. There is indeed research on ML-based pavement evaluation but there is not a widely used applicability by pavement management entities yet, so it is mandatory to work on the refinement of models and data collection methods

The Public Service Media and Public Service Internet Manifesto

This book presents the collectively authored Public Service Media and Public Service Internet Manifesto and accompanying materials.The Internet and the media landscape are broken. The dominant commercial Internet platforms endanger democracy. They have created a communications landscape overwhelmed by surveillance, advertising, fake news, hate speech, conspiracy theories, and algorithmic politics. Commercial Internet platforms have harmed citizens, users, everyday life, and society. Democracy and digital democracy require Public Service Media. A democracy-enhancing Internet requires Public Service Media becoming Public Service Internet platforms – an Internet of the public, by the public, and for the public; an Internet that advances instead of threatens democracy and the public sphere. The Public Service Internet is based on Internet platforms operated by a variety of Public Service Media, taking the public service remit into the digital age. The Public Service Internet provides opportunities for public debate, participation, and the advancement of social cohesion. Accompanying the Manifesto are materials that informed its creation: Christian Fuchs’ report of the results of the Public Service Media/Internet Survey, the written version of Graham Murdock’s online talk on public service media today, and a summary of an ecomitee.com discussion of the Manifesto’s foundations

A review of intrinsic self-sensing cementitious composites and prospects for their application in transport infrastructures

Monitoring of transport infrastructures, in terms of early damage detection, can prevent the loss of life and economic damage associated with sudden infrastructure collapse and inform timely intervention, such as repair, to increase the sustainability and service life of infrastructures. Self-sensing cementitious geocomposites with the ability to detect stress, strain, and damage based on a piezoresistive mechanism enable the development of more integrated and viable geomaterial monitoring solutions than existing monitoring technologies. Self-sensing cementitious geocomposites are composed of conductive phases embedded in cementitious geomaterials that exhibit both sensing ability and superior mechanical properties. The states of stress, strain, displacement, and damage in infrastructures can be investigated by analysing the change in their electrical resistance. In this review, different types of self-sensing composites, their preparation, influential parameters, and associated theoretical investigations are discussed in detail to inform future advances in the development of self-sensing geocomposites. The challenges of this technology have also been summarised. This review is expected to stimulate and inform research that explores the development and application prospects of self-sensing cementitious geocomposites.This work was supported by the European Commission-Shiff2Rail Program under the project “IN2TRACK2–826255-H2020-S2RJU-2018/H2020-S2RJU CFM-2018”. It is also partly financed by FCT/MCTES through national funds (PIDDAC), under the R&D Unit of the Institute for Sustainability and Innovation in Engineering Structures (ISISE; reference UIDB/04029/2020), as well as under the R&D Unit of the Centre for Textile Science and Technology (2C2T)