&lt;title&gt;Fiber optic Bragg grating sensors embedded in GFRP rockbolts&lt;/title&gt;

Frank, Andreas; Nellen, Philipp M.; Broennimann, Rolf; Sennhauser, U.

doi:10.1117/12.349767

Cited by 11 publications

(12 citation statements)

References 7 publications

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“…Embedding the fiber optic sensors inside the composite materials is very effective in transferring strain and protecting the fragile optical fiber from mechanical damage. Frank et al fabricated GFRP rock bolts instrumented with FBG sensors by embedding the FBG sensors in the GFRP rock bolts during the pultrusion process [ 41 ]. The tensile tests indicated that the embedded FBG sensors were able to survive a high strain of 1.5%.…”

Section: Rock Bolt Monitoring Using Smart Sensorsmentioning

confidence: 99%

A Review of Rock Bolt Monitoring Using Smart Sensors

Song

Wang

et al. 2017

Sensors

112

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Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.

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Section: Rock Bolt Monitoring Using Smart Sensorsmentioning

confidence: 99%

A Review of Rock Bolt Monitoring Using Smart Sensors

Song

Wang

et al. 2017

Sensors

112

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“…Existing packaging methods include gluing FBG to the target and embedding with adhesives [22,23,24,25,26], packaging FBG in pipes or on plates [25,27,28,29,30], or encapsulating FBG into composites or layered structures [20,31,32,33,34]. For field geohazard monitoring, the installation works can be extremely tricky since the optical fibers can hardly be adhered on geomaterials.…”

Section: Development Of Fbg-based Geohazard Monitoring Systemsmentioning

confidence: 99%

“…A common practice is to adhere the sensors on- or embed them in-soil reinforcements, such as geogrids, soil nails and anti-slide piles. As early as 1999, the use of glass fiber–reinforced polymer (GFRP) rock bolts with integrated FBG sensors for strain monitoring in a Switzerland tunnel was reported by Frank et al of the Swiss Federal Laboratories for Materials Testing and Research [31]. Nellen et al successfully monitored strain and temperature fields of tunnels with FBG instrumented GFRP rock bolts [35].…”

Section: Development Of Fbg-based Geohazard Monitoring Systemsmentioning

confidence: 99%

FBG-Based Monitoring of Geohazards: Current Status and Trends

Zhu

Shi

Zhang

2017

Sensors

122

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In recent years, natural and anthropogenic geohazards have occured frequently all over the world, and field monitoring is becoming an increasingly important task to mitigate these risks. However, conventional geotechnical instrumentations for monitoring geohazards have a number of weaknesses, such as low accuracy, poor durability, and high sensitivity to environmental interferences. In this aspect, fiber Bragg grating (FBG), as a popular fiber optic sensing technology, has gained an explosive amount of attention. Based on this technology, quasi-distributed sensing systems have been established to perform real-time monitoring and early warning of landslides, debris flows, land subsidence, earth fissures and so on. In this paper, the recent research and development activities of applying FBG systems to monitor different types of geohazards, especially those triggered by human activities, are critically reviewed. The working principles of newly developed FBG sensors are briefly introduced, and their features are summarized. This is followed by a discussion of recent case studies and lessons learned, and some critical problems associated with field implementation of FBG-based monitoring systems. Finally the challenges and future trends in this research area are presented.

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“…Nellen et al [10] embedded FBG sensors in the GFRP rock bolts in order to conduct pultrusion. The tensile evaluations showed that the embedded FBG sensors were capable of withstanding a high strain of 1.5%.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Difference in Measuring Bolt Stress: A Comparison of Two Optical Fiber Sensing Techniques

Chai

Liu

et al. 2018

Journal of Sensors

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Monitoring the load level of the rock bolts is of great importance for assessing risk. Based on the mechanical transmission mechanism of grouting bolts, the bolt pull-out test was carried out in lab. The performance of the bolt under pull-out loading was measured using the pulse-pre-pump Brillouin optical time domain analysis (PPP-BOTDA) and fiber Bragg grating (FBG) sensing technologies. The distribution characteristic of axial stress along the bolt was analysed in combination with the measurements obtained by the two sensing technologies. The relative standard deviation for repeatability errors in the determination and the setting time of resin grout was investigated. The results show that the distribution of axial stress is nonuniform along the anchorage section. The maximum value of axial stress on the bolt is closed to the pull-out side. The relative standard deviation for repeatability errors obtained by PPP-BOTDA is less than that obtained by FBG. The comparison of the measurements obtained by the two methods indicates that when the drawing force is greater than 20 kN and the axial stress is more than 10 kN, the two methods have better consistency. In the field application, it is necessary to estimate the deformation of matrix, leaving at least 500 minutes for resin bond to work.

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<title>Fiber optic Bragg grating sensors embedded in GFRP rockbolts</title>

Cited by 11 publications

References 7 publications

A Review of Rock Bolt Monitoring Using Smart Sensors

A Review of Rock Bolt Monitoring Using Smart Sensors

FBG-Based Monitoring of Geohazards: Current Status and Trends

Assessing the Difference in Measuring Bolt Stress: A Comparison of Two Optical Fiber Sensing Techniques

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