Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13834
Vassiliki Krey, Iordanis Galanis, V. Zacharis, M. Tsakiri
This study presents a method developed to analyze the position timeseries of continuously operated GNSS stations located in the area around the epicenter of an earthquake, aiming at the detection of secondary seismic waves. Specifically, 5 Ηz positioning data from 14 GNSS stations operated by UNAVCO were used, located in the areas of Southern California and Alaska, for two distinct earthquake events of a 7.1 moment magnitude each. The method described follows three steps: rotation of the position components, noise filtering of timeseries using Kalman’s filter and the use of a moving average to statistically indicate the point of time in which the maximum displacement induced by the S-wave takes place. This method statistically proves the existence of a motion generated from a geohazard in a position timeseries of continuously operated station(s) of interest and, in addition, it indicates the exact time of the incident. The method can be employed in testing for displacement of continuous GNSS stations in areas affected by an earthquake, as well as for generating conclusions on the velocity and direction of seismic waves’ propagation.
{"title":"S‐Wave detection using continuously operated GNSS stations: A case study of two Mw 7.1 earthquake events","authors":"Vassiliki Krey, Iordanis Galanis, V. Zacharis, M. Tsakiri","doi":"10.4995/jisdm2022.2022.13834","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13834","url":null,"abstract":"This study presents a method developed to analyze the position timeseries of continuously operated GNSS stations located in the area around the epicenter of an earthquake, aiming at the detection of secondary seismic waves. Specifically, 5 Ηz positioning data from 14 GNSS stations operated by UNAVCO were used, located in the areas of Southern California and Alaska, for two distinct earthquake events of a 7.1 moment magnitude each. The method described follows three steps: rotation of the position components, noise filtering of timeseries using Kalman’s filter and the use of a moving average to statistically indicate the point of time in which the maximum displacement induced by the S-wave takes place. This method statistically proves the existence of a motion generated from a geohazard in a position timeseries of continuously operated station(s) of interest and, in addition, it indicates the exact time of the incident. The method can be employed in testing for displacement of continuous GNSS stations in areas affected by an earthquake, as well as for generating conclusions on the velocity and direction of seismic waves’ propagation.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127356569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13921
Krzysztof Książek, S. Łapiński
Sensitivity analysis is one aspect of the calculation process in displacement measurement. For this purpose, sensitivity measures are used in the form of minimal detectable displacements ( ), derived from the definition of minimal detectable bias ( ). Analyses were performed based on disturbing the parameter vector with the value (calculated from principal component analysis). Analyses were considered for displacements of the levelling network based on the global vector ( ). The calculations were conducted using the least squares adjustment with pseudo-random observations. The mean success rate ( ) was used to perform the detection analyses. The effectiveness of the global test agrees with the assumed power of the test. Local tests for a single point showed 48.6 % displacements of more than one point. It should be considered using another local test for the case of displacements of multiple points. This study concludes that in addition to the accuracy of the designed network points, the network configuration is also important in sensitivity analyses. The research shows that sensitivity analyses should be considered at the design stage of control networks, i.e. to determine at what level a given network is able to detect displacement.
{"title":"Sensitivity analysis of control networks in terms of minimal detectable displacements","authors":"Krzysztof Książek, S. Łapiński","doi":"10.4995/jisdm2022.2022.13921","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13921","url":null,"abstract":"Sensitivity analysis is one aspect of the calculation process in displacement measurement. For this purpose, sensitivity measures are used in the form of minimal detectable displacements ( ), derived from the definition of minimal detectable bias ( ). Analyses were performed based on disturbing the parameter vector with the value (calculated from principal component analysis). Analyses were considered for displacements of the levelling network based on the global vector ( ). The calculations were conducted using the least squares adjustment with pseudo-random observations. The mean success rate ( ) was used to perform the detection analyses. The effectiveness of the global test agrees with the assumed power of the test. Local tests for a single point showed 48.6 % displacements of more than one point. It should be considered using another local test for the case of displacements of multiple points. This study concludes that in addition to the accuracy of the designed network points, the network configuration is also important in sensitivity analyses. The research shows that sensitivity analyses should be considered at the design stage of control networks, i.e. to determine at what level a given network is able to detect displacement.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131684731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13829
Jorge Juan Romo-Berlana, M. Sánchez-Fernández, José Juan de Sanjosé-Blasco, Fernando Berenguer-Sempere
The preservation of cultural heritage must encompass different disciplines for its management to be optimal. The behaviour of a historic building depends on many factors, which include its real geometry, the characteristics of the materials with which it was built, pathologies arising throughout its existence and the conditions of its surroundings. Different techniques are therefore required and these must be complemented in order to manage our cultural heritage comprehensively. Coria Cathedral (Cáceres) is an example of a singular building with secular pathologies. This study of the cathedral combined modern techniques of analysis and description. Geomatic techniques were used (differential levelling, terrestrial laser scanner, GNSS), geophysical prospecting methods (electrical tomography), geotechnical descriptive methods, three-dimensional modelling and verification of structural systems. The results obtained served as the basis to determine and locate the origin building's pathologies and to develop a project for the structural consolidation.
{"title":"Pathological diagnostic tool based on the combination of different disciplines. Management of the preservation of cultural heritage. Application in the structural consolidation of rock structures","authors":"Jorge Juan Romo-Berlana, M. Sánchez-Fernández, José Juan de Sanjosé-Blasco, Fernando Berenguer-Sempere","doi":"10.4995/jisdm2022.2022.13829","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13829","url":null,"abstract":"The preservation of cultural heritage must encompass different disciplines for its management to be optimal. The behaviour of a historic building depends on many factors, which include its real geometry, the characteristics of the materials with which it was built, pathologies arising throughout its existence and the conditions of its surroundings. Different techniques are therefore required and these must be complemented in order to manage our cultural heritage comprehensively. Coria Cathedral (Cáceres) is an example of a singular building with secular pathologies. This study of the cathedral combined modern techniques of analysis and description. Geomatic techniques were used (differential levelling, terrestrial laser scanner, GNSS), geophysical prospecting methods (electrical tomography), geotechnical descriptive methods, three-dimensional modelling and verification of structural systems. The results obtained served as the basis to determine and locate the origin building's pathologies and to develop a project for the structural consolidation.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124752371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13885
A. M. Ruiz-Armenteros, M. Sánchez-Gómez, J. M. Delgado-Blasco, M. Bakon, A. Ruiz-Constán, J. Galindo‐Zaldívar, M. Lazecký, Miguel Marchamalo-Sacristán, J. J. Sousa
Cities in Spain use to be overgrown around old towns (preroman, roman and medieval) constructed on topographic defensive heights of singular geological features. In the upper Guadalquivir valley, a tabular body of Miocene sediments has been eroded forming mesas where most of its population has been living since middle age. As the towns grew, new neighborhoods settled towards the edges and cliffs of these mesas, in areas with high probabilities of instability. The town of Arjona is a good example of this geological-urbanistic setup, located on the tabular hill formed by clay marls topped by bioclastic limestones that protect it from erosion. Modern buildings from few sectors of the town show important cracks, even the 16th century bell-tower has a 4º inclination indicating problems in the foundations. Multi-temporal SAR interferometry (MT-InSAR) is a powerful technique to derive displacement time series over coherent targets on the Earth associated with geophysical or structural instabilities phenomena. In this work we use MT-InSAR with Sentinel-1 data to reveal that, at present day, the periphery of Arjona is active, being recognized a large landslide in the south side of this mesa town which affects buildings and civil infrastructures. In addition, field work is being carried out to investigate the sources of these instabilities.
{"title":"Monitoring instabilities by MT-InSAR in a mesa placed town (Arjona, Guadalquivir valley, South Spain)","authors":"A. M. Ruiz-Armenteros, M. Sánchez-Gómez, J. M. Delgado-Blasco, M. Bakon, A. Ruiz-Constán, J. Galindo‐Zaldívar, M. Lazecký, Miguel Marchamalo-Sacristán, J. J. Sousa","doi":"10.4995/jisdm2022.2022.13885","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13885","url":null,"abstract":"Cities in Spain use to be overgrown around old towns (preroman, roman and medieval) constructed on topographic defensive heights of singular geological features. In the upper Guadalquivir valley, a tabular body of Miocene sediments has been eroded forming mesas where most of its population has been living since middle age. As the towns grew, new neighborhoods settled towards the edges and cliffs of these mesas, in areas with high probabilities of instability. The town of Arjona is a good example of this geological-urbanistic setup, located on the tabular hill formed by clay marls topped by bioclastic limestones that protect it from erosion. Modern buildings from few sectors of the town show important cracks, even the 16th century bell-tower has a 4º inclination indicating problems in the foundations. Multi-temporal SAR interferometry (MT-InSAR) is a powerful technique to derive displacement time series over coherent targets on the Earth associated with geophysical or structural instabilities phenomena. In this work we use MT-InSAR with Sentinel-1 data to reveal that, at present day, the periphery of Arjona is active, being recognized a large landslide in the south side of this mesa town which affects buildings and civil infrastructures. In addition, field work is being carried out to investigate the sources of these instabilities.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117097209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13866
Véronique Le Corvec, Patrick Lézin, F. Cartiaux
During the fire which took place on 15th April 2019, the Cathedral of Notre Dame de Paris underwent extensive structural damages: most of the roof was destroyed, part of the stone vaulted ceiling collapsed, and the wooden framework of the north tower was partially burned. After the fire, a list of actions was carried on in order to secure the remaining structure, prevent any further damage and start the rehabilitation. Very early on, a monitoring system was used to assist the project manager in these tasks. With the progress of site works, the monitoring system was updated to provide more insightful information. The present paper focuses on the monitoring system deployed on the towers and the stone vaulted ceiling with the objective to produce a first assessment of the current state and follow the evolution during the reconstruction phase. The monitoring campaign was carried out from December 2020 to December 2021 with two distinct sets of sensors. The first objective was to characterize the current state and identify the dynamic behavior of the structure, for that purpose 48 directional accelerometers were installed on the two towers and the two vaults lane. Acceleration measurements and analytical methods lead to the identification of the fundamental modes of these structural elements. In a second time, to follow the evolution of the vaults, 56 inclinometers were positioned on the outer side of the vaults, constituting 15 inclinometer measuring chains. Set up to transmit data continuously with a 10 min frequency, measurements allow to notify settlements or uprisings and correlate these evolutions with external factors (weather conditions or rehabilitation works).
{"title":"Static and Dynamic Monitoring of the Notre Dame de Paris Cathedral","authors":"Véronique Le Corvec, Patrick Lézin, F. Cartiaux","doi":"10.4995/jisdm2022.2022.13866","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13866","url":null,"abstract":"During the fire which took place on 15th April 2019, the Cathedral of Notre Dame de Paris underwent extensive structural damages: most of the roof was destroyed, part of the stone vaulted ceiling collapsed, and the wooden framework of the north tower was partially burned. After the fire, a list of actions was carried on in order to secure the remaining structure, prevent any further damage and start the rehabilitation. Very early on, a monitoring system was used to assist the project manager in these tasks. With the progress of site works, the monitoring system was updated to provide more insightful information. The present paper focuses on the monitoring system deployed on the towers and the stone vaulted ceiling with the objective to produce a first assessment of the current state and follow the evolution during the reconstruction phase. The monitoring campaign was carried out from December 2020 to December 2021 with two distinct sets of sensors. The first objective was to characterize the current state and identify the dynamic behavior of the structure, for that purpose 48 directional accelerometers were installed on the two towers and the two vaults lane. Acceleration measurements and analytical methods lead to the identification of the fundamental modes of these structural elements. In a second time, to follow the evolution of the vaults, 56 inclinometers were positioned on the outer side of the vaults, constituting 15 inclinometer measuring chains. Set up to transmit data continuously with a 10 min frequency, measurements allow to notify settlements or uprisings and correlate these evolutions with external factors (weather conditions or rehabilitation works).","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130187139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13863
Kamila Pawłuszek-Filipiak, Maya Ilieva, Natalia Wielgocka, Krzysztof Stasch
EPOS-PL+ is the Polish national realization of the European Plate Observing System (EPOS) project that aims to build a multidisciplinary infrastructure. It allows integration of a variety of geoscience expertise and techniques to better understand the geohazard related to the underground mining of coal in the Upper Silesian Coal Basin (USCB) in Poland. The study case in this project is the Marcel Mine, located within USCB, where the detected subsidence for the analyzed period of four months reaches 91 cm. Various interferometric processing techniques demonstrated some advantages and also some limitations in the context of mining deformation measurement, including accuracy, spatial resolution, detectable deformation rate, atmospheric delay, and ability to detect the maximal deformation gradients. This is especially important from a mining perspective. Therefore, we investigated three different interferometric processing techniques to monitor fast mining deformation in the Marcel hard coal mine area. More specifically, we used conventional DInSAR, Small Baseline Subsets (SBAS), and Persistent Scattered Interferometry (PSInSAR). The result confirmed that none of these methods can be considered as the best. The DInSAR approach allows capturing the maximal deformation gradient, which was not possible with the PSInSAR and SBAS approaches. On the contrary, PSInSAR and SBAS allow us to provide less noisy and reliable results in the area of safety pillars.
{"title":"Evaluation of synthetic aperture radar interferometric techniques for monitoring of fast deformation caused by underground mining exploitation","authors":"Kamila Pawłuszek-Filipiak, Maya Ilieva, Natalia Wielgocka, Krzysztof Stasch","doi":"10.4995/jisdm2022.2022.13863","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13863","url":null,"abstract":"EPOS-PL+ is the Polish national realization of the European Plate Observing System (EPOS) project that aims to build a multidisciplinary infrastructure. It allows integration of a variety of geoscience expertise and techniques to better understand the geohazard related to the underground mining of coal in the Upper Silesian Coal Basin (USCB) in Poland. The study case in this project is the Marcel Mine, located within USCB, where the detected subsidence for the analyzed period of four months reaches 91 cm. Various interferometric processing techniques demonstrated some advantages and also some limitations in the context of mining deformation measurement, including accuracy, spatial resolution, detectable deformation rate, atmospheric delay, and ability to detect the maximal deformation gradients. This is especially important from a mining perspective. Therefore, we investigated three different interferometric processing techniques to monitor fast mining deformation in the Marcel hard coal mine area. More specifically, we used conventional DInSAR, Small Baseline Subsets (SBAS), and Persistent Scattered Interferometry (PSInSAR). The result confirmed that none of these methods can be considered as the best. The DInSAR approach allows capturing the maximal deformation gradient, which was not possible with the PSInSAR and SBAS approaches. On the contrary, PSInSAR and SBAS allow us to provide less noisy and reliable results in the area of safety pillars.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115036208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13899
A. M. Ruiz-Armenteros, W. Souza, J. Cabral
One of the main causes of land subsidence in the world is the exploitation of groundwater above the regeneration capacity of the aquifer systems. However, the rapid urban growth in estuarine areas can also contribute to the development of this phenomenon. An example of this occurs in the city of Recife, northeastern Brazil. The municipality is built on an estuarine plain composed of several rivers (Capibaribe, Beberibe, Tejipió), which formation results from the occupation of humid areas and mangroves. In recent decades, the excessive removal of water resources from the subsoil has caused the reduction of more than 100 meters of the deep aquifer piezometric level in some places. The presence of these factors in Recife may contribute to land subsidence. To detect this phenomenon, the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique was used. The dataset consisted of 135 Sentinel-1A Interferometric Wide (IW) Single Look Complex (SLC) images from September 2016 to April 2021. The images were acquired in descending orbits and VV polarization. The results of the PSInSAR analysis reveal that in Recife there are several areas of land subsidence with a rate close to -15 mm/year. The main occurrence of soil settlement is observed in large recently built areas in the west zone, and small areas in the north zone. Minor cases occur in the southern zone due to the exploitation of groundwater. The identification of these land subsidence areas can help in the study of urban drainage to avoid flooding sites and in the adoption of mitigating measures for the suitable use of underground water resources.
{"title":"Monitoring of land subsidence in the city of Recife/Brazil using Sentinel-1 SAR interferometry","authors":"A. M. Ruiz-Armenteros, W. Souza, J. Cabral","doi":"10.4995/jisdm2022.2022.13899","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13899","url":null,"abstract":"One of the main causes of land subsidence in the world is the exploitation of groundwater above the regeneration capacity of the aquifer systems. However, the rapid urban growth in estuarine areas can also contribute to the development of this phenomenon. An example of this occurs in the city of Recife, northeastern Brazil. The municipality is built on an estuarine plain composed of several rivers (Capibaribe, Beberibe, Tejipió), which formation results from the occupation of humid areas and mangroves. In recent decades, the excessive removal of water resources from the subsoil has caused the reduction of more than 100 meters of the deep aquifer piezometric level in some places. The presence of these factors in Recife may contribute to land subsidence. To detect this phenomenon, the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique was used. The dataset consisted of 135 Sentinel-1A Interferometric Wide (IW) Single Look Complex (SLC) images from September 2016 to April 2021. The images were acquired in descending orbits and VV polarization. The results of the PSInSAR analysis reveal that in Recife there are several areas of land subsidence with a rate close to -15 mm/year. The main occurrence of soil settlement is observed in large recently built areas in the west zone, and small areas in the north zone. Minor cases occur in the southern zone due to the exploitation of groundwater. The identification of these land subsidence areas can help in the study of urban drainage to avoid flooding sites and in the adoption of mitigating measures for the suitable use of underground water resources.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128434807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13862
Wolfgang Wiedemann, C. Holst
Water dams are an important infrastructure component for energy generation, water supply and flood control. Regular inspections of the structures for damage and deformation are necessary for safe operation and to ensure stability. In addition to the traditional concepts of geodetic network measurement, laser scan data can be used to deliver areal information on deformation. Within this topic, we aim at developing a method that identifies individual rocks of dam walls within the laser scans to introduce them as identical feature points for a rigorous deformation analysis. For this purpose, it is necessary to identify the solid stone surfaces on the water dams from scan data, and separated them from vegetation and joints. In this paper, we investigate method for identification of individual stones on gravity dams made of rubble stones. For the segmentation, the intensity values, RGB color information and local geometric structure from textured point clouds acquired with Terrestrial Laser Scanners are investigated. The classification should be robust against outer measurement conditions and provide sharp object boundaries. Our results show that – although many different methods are available – a reliable classification of single rubble stones is still a challenge task.
{"title":"Identifying individual rocks within laser scans for a rigorous deformation analysis of water dams","authors":"Wolfgang Wiedemann, C. Holst","doi":"10.4995/jisdm2022.2022.13862","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13862","url":null,"abstract":"Water dams are an important infrastructure component for energy generation, water supply and flood control. Regular inspections of the structures for damage and deformation are necessary for safe operation and to ensure stability. In addition to the traditional concepts of geodetic network measurement, laser scan data can be used to deliver areal information on deformation. Within this topic, we aim at developing a method that identifies individual rocks of dam walls within the laser scans to introduce them as identical feature points for a rigorous deformation analysis. For this purpose, it is necessary to identify the solid stone surfaces on the water dams from scan data, and separated them from vegetation and joints. In this paper, we investigate method for identification of individual stones on gravity dams made of rubble stones. For the segmentation, the intensity values, RGB color information and local geometric structure from textured point clouds acquired with Terrestrial Laser Scanners are investigated. The classification should be robust against outer measurement conditions and provide sharp object boundaries. Our results show that – although many different methods are available – a reliable classification of single rubble stones is still a challenge task.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131504687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13813
Tomislav Medic, Nicholas Meyer, Lorenz Schmid, A. Wieser
Profile laser scanning allows sub-millimeter precise contact-free measurements with high spatial and temporal resolution. That makes it an appealing solution for structural health monitoring focusing on vibrations of engineering structures, such as the analysis of eigenmodes and eigenfrequencies of bridges. In this work, we use the profile scanning mode of a Zoller+Fröhlich Imager 5016 terrestrial laser scanner (TLS) to observe bridge dynamics, focusing on the free decay processes following trains passing the bridge and exciting the structure. We compare two vibration monitoring strategies and implement an open-source semi-automatic software that integrates both approaches. We successfully estimate a spatio-temporal vibration model (including dampening coefficient) despite the maximum vibration amplitude reaching only 0.3 mm during the free decay process. Both strategies allow the estimation of the first eigenfrequency with a precision better than 0.1 Hz. Within the paper, we highlight the advantages and tackle the identified challenges of these vibration monitoring strategies. We also report on a preliminary investigation of appropriate instrument positioning for estimating the parameters of a spatio-temporal vibration model.
{"title":"Vibration monitoring of a bridge using 2D profile laser scanning: Lessons learned from the comparison of two spatio-temporal processing strategies","authors":"Tomislav Medic, Nicholas Meyer, Lorenz Schmid, A. Wieser","doi":"10.4995/jisdm2022.2022.13813","DOIUrl":"https://doi.org/10.4995/jisdm2022.2022.13813","url":null,"abstract":"Profile laser scanning allows sub-millimeter precise contact-free measurements with high spatial and temporal resolution. That makes it an appealing solution for structural health monitoring focusing on vibrations of engineering structures, such as the analysis of eigenmodes and eigenfrequencies of bridges. In this work, we use the profile scanning mode of a Zoller+Fröhlich Imager 5016 terrestrial laser scanner (TLS) to observe bridge dynamics, focusing on the free decay processes following trains passing the bridge and exciting the structure. We compare two vibration monitoring strategies and implement an open-source semi-automatic software that integrates both approaches. We successfully estimate a spatio-temporal vibration model (including dampening coefficient) despite the maximum vibration amplitude reaching only 0.3 mm during the free decay process. Both strategies allow the estimation of the first eigenfrequency with a precision better than 0.1 Hz. Within the paper, we highlight the advantages and tackle the identified challenges of these vibration monitoring strategies. We also report on a preliminary investigation of appropriate instrument positioning for estimating the parameters of a spatio-temporal vibration model.","PeriodicalId":404487,"journal":{"name":"Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134054064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.4995/jisdm2022.2022.13917
P. Psimoulis, Ali Algadhi, Athina Grizi, L. Neves
Retaining walls are a critical infrastructure of transportation networks and the monitoring of their condition is crucial for the efficient and reliable maintenance of the network. The condition of retaining walls is frequently assessed using qualitative criteria and visual inspection, which are susceptible to human-bias and errors. To improve the management of these structures, reducing the probability of failure and the maintenance costs, it is critical to develop more efficient, reliable and quantitative monitoring approaches for these structures. The current study aims to evaluate the performance of Terrestrial Laser Scanner (TLS) in deformation monitoring of retaining walls, based on the analysis of single scans (without registering the point clouds to build 3D models). The evaluation was based on a controlled experiment, where a wooden frame (1.5m x 1m) was used to simulate deformation scenarios for retaining walls, with an amplitude between 2 to 16 mm. A Leica RTC360 scanner was used to scan the wooden frame from distances varying between 10 to 27 m and angles varying between 0° to 20°. Five methods were applied to analyse the laser-scanner data and estimate the displacement: a target-based approach and four cloud-based approaches including the Cloud-to-Cloud (C2C), the Cloud-to-Mesh (C2M), the Multiscale-Model-to-Model-Cloud-Comparison (M3C2), and an alternative cloud-based method where the mean average of the point-cloud was used to estimate the displacement in the axis of the deformation. A Robotic Total Station Leica TS30 was also used to measure the deformation of the wooden frame and provide the ground truth values of the introduced deformation for each scenario. The results showed that the RTC360 had an accuracy of 1.3 mm with a confidence level of 95%.
挡土墙是交通网络的重要基础设施，其状态监测对交通网络的高效可靠维护至关重要。挡土墙的状况经常使用定性标准和目视检查来评估，这容易受到人为偏见和错误的影响。为了提高对这些结构的管理，降低其故障概率和维修成本，开发更有效、可靠和定量的监测方法至关重要。目前的研究旨在评估地面激光扫描仪(TLS)在挡土墙变形监测中的性能，基于单次扫描分析(不注册点云来建立3D模型)。评估基于对照实验，其中使用木制框架(1.5m x 1m)模拟挡土墙的变形场景，幅度在2至16 mm之间。使用徕卡RTC360扫描仪对木框架进行扫描，扫描距离为10 ~ 27米，角度为0°~ 20°。采用了五种方法来分析激光扫描仪数据并估计位移:基于目标的方法和四种基于云的方法，包括云到云(C2C)、云到网格(C2M)、多尺度模型到模型-云比较(M3C2)，以及一种基于云的替代方法，该方法使用点云的平均值来估计变形轴上的位移。还使用徕卡机器人全站仪TS30测量木框架的变形，并提供每种情况下引入变形的地面真值。结果表明，RTC360的测量精度为1.3 mm，置信水平为95%。
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