Field monitoring of piling effects on a nearby masonry vault using distributed sensing (original) (raw)
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Géotechnique
Heritage masonry structures require detailed monitoring during nearby underground construction, to address the concerns of building owners and mitigate uncertainties relating to the soil–structure system. This paper discusses innovative displacement and strain monitoring of a listed masonry church undergoing ground movements due to nearby tunnelling in London Clay. In addition to conventional surveying and tilt monitoring, laser scan displacement monitoring and fibre optic strain sensing was conducted. Prior to construction, point clouds of the structure were used to map pre-existing geometric distortions in the structure. During construction, detailed monitoring of displacements and strains was conducted across the building facades and the tower. The same techniques were also used to monitor the painted dome of the church where conventional displacement monitoring was not feasible. With a focus on the new engineering insight provided by the innovative monitoring techniques, the imp...
2018
Retaining walls are important structures to stabilize slopes in the vicinity of infrastructure objects like buildings, highways and tunnel portals. In Austria, conventional monitoring of these walls is based on visual inspection and on deformation measurements of a few distinctive points on or within the structure. However, these approaches leave large areas of retaining walls unobserved and thus relevant structural deficiencies may be missed. We present a new approach consisting of remote surface based measurements with mobile mapping systems and internal deformation measurements with high resolution distributed fibre optic sensors. For the remote sensing, a measurement platform consisting of two laser scanners, an inertial measurement unit (IMU), a differential GNSS sensor and several cameras was used. Whilst a standard car with the attached multi sensor system platform travels with up to 100 km/h along the highway, data is continuously recorded with high frequency. As a result, g...
Surveying and Monitoring for Vulnerability Assessment of an Ancient Building
Sensors, 2013
This paper examines how surveying and monitoring improve our knowledge about ancient buildings, allow the interpretation of their structural response and help in the search for the best solutions for their conservation. The case study of Palazzo del Capitano in Mantua (Italy) is analyzed. In particular, the attention is focused on the use of a Terrestrial Laser Scanner (TLS) for surveying and monitoring too, considering that the building structural control has been performed in combination with other traditional topographic techniques such as geometric leveling and topographic networks for 3D control based on measurements through total stations. The study of TLS monitoring has been tested only in the last decade and it is an innovative method for the detection of displacements of particular surfaces. Till now the research has focused only on the use of TLS monitoring to control large structures and in particular landscape situations; thus its use for a civil construction and historical buildings is a new field of investigation. Despite the fact technological development and new methodologies seem offer new future potential for the analysis of ancient buildings, currently there are still important limits for the application of the investigated surveying and monitoring techniques.
Automation in Construction, 2020
This paper addresses the implementation of a Distributed Optical Fiber Sensor system (DOFS) to the TMB L-9 metro tunnel in Barcelona for Structural Health Monitoring (SHM) purposes as the former could potentially be affected by the construction of a nearby residential building. With the aim of assessing the performance of this newly developed monitoring technology, an indepth analysis on the collected strain readings is performed from which innovative data postprocessing techniques are developed. Finally, the reliability of the installed DOFSs system is studied by means of a comparison with a theoretical model of the site's structural conditions.
Integrated Use of Measurements for the Structural Diagnosis in Historical Vaulted Buildings
Sensors
The process of the structural diagnosis of historical buildings is analyzed. The correlation of different data is a fundamental issue, related to the multidisciplinary nature of the study of built heritage. Quantitative data are collected by sensors, these being environmental data (temperature and humidity) or cracks (displacements). Another important source being qualitative data, derived from historic investigation, diagnostic investigations, etc. However sometimes the results may be difficult to correlate due to the different nature of the data, being quantitative and qualitative, as well as spread over the long life of the construction. In particular, the here proposed methodology suggests the use of light detection and ranging (LiDAR) scanning for the geometric and structural deformation survey, damage survey, historic evolution, monitoring of the crack pattern and environmental data. The integrated use of the collected data with digital and finite element models is investigate...
Long-term monitoring of reinforced earth structures using distributed fiber optic sensing
Journal of Civil Structural Health Monitoring, 2016
Reinforced earth structures are commonly used to construct earth structures with high inclination angles. The stability and safety of such constructions is highly dependent on the strain distribution of the geogrids inside the earth structure. In this article, we report about the development and implementation of a structural monitoring system to measure the strain distribution of geogrids with high accuracy and high spatial resolution. The system was developed for the Semmering Base Tunnel project in Austria but can also be applied to other reinforced earth structures. The Semmering Base Tunnel is one of the core infrastructure projects in central Europe. Prior to the start of the actual tunnel excavation, comprehensive preparatory works in the alpine landscape were necessary. One of these works included the relocation of a river stream at the disposal site Longsgraben. To establish this relocation, a reinforced earth structure with a total length of more than 1.3 km and heights up to 25 m was constructed. To evaluate the stability of this structure, a monitoring system was developed. This monitoring system is thereby based on external geodetic and internal distributed fiber optic measurements. For the latter, about 2 km of Brillouin sensing cables in several sensor sections were installed in the project area. In this paper, we report about the laboratory experiments to determine strain and temperature coefficients for the conversion of the measured Brillouin frequency shifts into strain or temperature values. Furthermore, the long-term behavior of the monitoring structure is analyzed for the period of 1 year after installation.
2018
In 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 litera...