Application of Distributed Fiber Optic Sensing Technique to Monitor Stability of a Geogrid-Reinforced Model Slope

In recent years, the technology of optical fibers has rapidly gained ground in many areas of science and industry, including the construction industry. In this article, the technology of optical fibers based on a fiber Bragg grating (FBG) was used to determine tensile forces acting in a basal reinforcement of a scaled down physical model, which included piled embankment and basal reinforcement. Installing FBG sensors on the geogrid made monitoring of axial strains possible, thus allowing determination of the behavior of the basal reinforcement of the piled embankment. On the basis of three tests performed on the physical model, numerical model calibration with the physical model was carried out using the software PLAXIS 3D Tunnel 2.4. The results showed accurate predictions, especially for the low and middle part of the measured deformations where the numerical analysis proposed a solution that can be considered as safe. Installing FBG sensors on biaxial geogrids was a bold idea that was not easy to implement. However, other possibilities have been successfully tested, such as high-frequency measurements of the response of reinforced soil structure under dynamic loading.

Section: Discussionmentioning

confidence: 99%

Measurement of Axial Strain of Geogrid by Optical Sensors

Drusa

Kais²,

Dubovan

et al. 2021

“…The combination of FOSs and geogrids for the strengthening of geotechnical structures e.g., [ 91 , 92 , 93 ] or FOSs and reinforcing composite patches based on either fiber reinforced plastics (FRPs) [ 94 ] or Fiber Reinforced Cementitious Matrix (FRCM) [ 95 ], for the rehabilitation of concrete structures, have been already explored in the literature. However, the integration of optical fiber sensors in TRC is still in the early stages of development, and thus, there is no sufficient literature available to compare their performance, structurally or in terms of efficiency and economy.…”

Section: Functionalizing Textile-based Reinforcement Structure With Fossmentioning

confidence: 99%

Fiber Optic Sensors Embedded in Textile-Reinforced Concrete for Smart Structural Health Monitoring: A Review

Alwis

Bremer

Roth

2021

The last decade has seen rapid developments in the areas of carbon fiber technology, additive manufacturing technology, sensor engineering, i.e., wearables, and new structural reinforcement techniques. These developments, although from different areas, have collectively paved way for concrete structures with non-corrosive reinforcement and in-built sensors. Therefore, the purpose of this effort is to bridge the gap between civil engineering and sensor engineering communities through an overview on the up-to-date technological advances in both sectors, with a special focus on textile reinforced concrete embedded with fiber optic sensors. The introduction section highlights the importance of reducing the carbon footprint resulting from the building industry and how this could be effectively achieved by the use of state-of-the-art reinforcement techniques. Added to these benefits would be the implementations on infrastructure monitoring for the safe operation of structures through their entire lifespan by utilizing sensors, specifically, fiber optic sensors. The paper presents an extensive description on fiber optic sensor engineering that enables the incorporation of sensors into the reinforcement mechanism of a structure at its manufacturing stage, enabling effective monitoring and a wider range of capabilities when compared to conventional means of structural health monitoring. In future, these developments, when combined with artificial intelligence concepts, will lead to distributed sensor networks for smart monitoring applications, particularly enabling such distributed networks to be implemented/embedded at their manufacturing stage.

“…With the development of optical measuring and packaging technologies, the scope for the use of optical fiber sensors has been expanding to various application fields. In this regard, fiber Bragg grating (FBG) sensors and distributed temperature sensing (DTS) are being actively applied for slope stability monitoring in the geotechnical fields [ 1 , 2 , 3 , 4 ] and temperature monitoring in the geophysical fields [ 4 , 5 , 6 , 7 , 8 , 9 ], respectively. Recently, distributed acoustic sensing (DAS), among distributed optical fiber sensing (DOFS) technologies, has been actively investigated for seismic survey and passive monitoring, including earthquake and micro-seismic monitoring.…”

Section: Introductionmentioning

confidence: 99%

Protection and Installation of FBG Strain Sensor in Deep Boreholes for Subsurface Faults Behavior Monitoring

Choi

Park

et al. 2021

Fiber optic sensors are gradually replacing electrical sensors in geotechnical applications owing to their immunity to electrical interference, durability, and cost-effectiveness. However, additional protective measures are required to prevent loss of functionality due to damage to the sensors, cables, or connection parts (splices and/or connectors) during installation and completion processes in borehole applications. We introduce two cases of installing fiber Bragg grating (FBG) strain sensors in 1 km boreholes to monitor the behavior of deep subsurface faults. We present our fiber-reinforced plastic (FRP) forming schemes to protect sensors and splices. We also present uniaxial load test and post-completion monitoring results for assessing the effects and performance of the protective measures. The uniaxial load test and post-completion monitoring show that FBG sensors are well protected by FRP forming without significant impact on sensor performance itself and that they are successfully installed in deep boreholes. In addition to summarizing our learning from experiences, we also suggest several points for consideration to improve the applicability of FBG sensors in borehole environment of the geotechnical field.