Applications of BOTDR fiber optics to the monitoring of underground structures

Moffat, Ricardo; Beltrán, Juan Felipe; Herrera, Ricardo

doi:10.12989/gae.2015.9.3.397

Cited by 31 publications

(20 citation statements)

References 7 publications

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“…In addition to the interferometric measurement approach, it is necessary to mention approaches in the form of distributed systems like distributed strain and temperature sensing (DSTS) [33][34][35] or fiber Bragg grating sensors [36][37][38][39][40][41][42]. Both technologies work on a different principle and bring some advantages and disadvantages to the field of civil engineering, but based on our best opinion for the measurement of ground vibrations due to the vibratory roller, we chose and proposed a solution based on the fiber-optic interferometer.…”

Section: State-of-the-artmentioning

confidence: 99%

Alternative Approaches to Measurement of Ground Vibrations Due to the Vibratory Roller: A Pilot Study

Nedoma

Stolárik

Kepák

et al. 2019

Sensors

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At present, one of the primary tasks of the construction industry is to build transport infrastructure. This concerns both the construction of new bypasses of towns and the repair of existing roads, which are damaged by congestion, especially by freight transport. Whether it is a new building or a reconstruction, it is always very important to choose a suitable method of subsoil treatment. One of the most commonly used methods for soil treatment is currently compaction using vibratory rollers. This method is very effective both in terms of results and due to its low financial demands compared to other methods. Vibration is transmitted to the surrounding rock environment when compacting the subsoil using vibratory rollers. Although the intensity of these vibrations is not as pronounced as in other methods of subsoil treatment, such vibrations can have a significant effect, for example during compaction in urban areas or in an area with the presence of historical objects. Therefore, it is very advisable to monitor the effect of these vibrations on the environment during construction. This paper brings an original experimental comparative study of standard seismic instrumentation with a developed interferometric sensor for the field of monitoring vibrations generated during compaction of subsoil using vibrating rollers. The paper presents time and frequency domain results, as well as attenuation curves, which represent real attenuation of vibrations in a given rock environment. The results presented here show that a system operating on a different physical principle from the one used at present has the potential to replace the existing, very expensive, seismic equipment.

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Section: State-of-the-artmentioning

confidence: 99%

Alternative Approaches to Measurement of Ground Vibrations Due to the Vibratory Roller: A Pilot Study

Nedoma

Stolárik

Kepák

et al. 2019

Sensors

View full text Add to dashboard Cite

show abstract

“…The maximum axial strain was recorded as always lower than the elastic strain limit of the fiber (1%). Additional details of the system and examples of measurements can be found in [16,17]. The optical fiber was attached to the steel bar using plastic cable tie, and this was a fast and easy task on the field.…”

Section: Optical Fibermentioning

confidence: 99%

Monitoring a 28.5 m High Anchored Pile Wall in Gravel Using Various Methods

Moffat

Parra

Carrasco

2019

Sensors

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Horizontal displacements of a multiple-anchor pile wall in a 28.5 m deep excavation using the top-down construction method have been monitored using optical fiber (Brillouin optical time-domain reflectometry (BOTDR)), strain gauges, inclinometers, and a topographic survey. This work presents a comparison between these different techniques to measure horizontal displacements in the pile at several stages of the soil excavation process. It was observed that displacements can be separated into two components: Rigid body motion and pile flexural deformation. Measurements using optical fiber and inclinometers are considered the most adequate and easy to install. A numerical model allows us to evaluate the influence of earth pressure on the estimated horizontal displacements. It is shown that using soil pressure on the wall given by p = 0.65Kaγh, on a simplified modeled wall, provides a close deduction of horizontal displacements compared to observed values on the field.

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“…Contact sensors include a variety of tools: extensometers, strain gauges, fibre optic systems and microseismic receivers (Kumar et al 2011;Moffat et al 2015;Maleki & McVey 1988). These sensors, although very accurate, pose the same limitations as in surface mining:…”

Section: Deformation Monitoring In Undergroundmentioning

confidence: 99%

A novel radar-based system for underground mine wall stability monitoring

Cecchetti¹,

Rossi²,

Coppi³

et al. 2017

Proceedings of the First International Conference on Underground Mining Technology

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Ground collapse is a serious issue for underground mining, and currently there is a lack of remote sensing monitoring systems to perform real-time deformation monitoring. Extensometers can be used in several situations; however, this instrumentation obliges the user to work close to unstable areas, thus a remote monitoring system would offer noticeably improved safety conditions. IDS GeoRadar, a provider of radar technology for slope monitoring in surface mining, recently developed an interferometric radar system for underground operations to monitor ground fall precursors and provide early warning in order to evacuate people and machinery at risk. This radar system is able to monitor slow deformations to produce preliminary risk assessment on potentially exposed instabilities in underground areas. The new radar system is able to provide sub-millimetre displacement accuracy at a spatial resolution of tens of centimetres, with updated displacement information every 30 seconds. In this paper, the system is described, along with performance test results and assessment of monitoring performances in real scenarios.

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Applications of BOTDR fiber optics to the monitoring of underground structures

Cited by 31 publications

References 7 publications

Alternative Approaches to Measurement of Ground Vibrations Due to the Vibratory Roller: A Pilot Study

Alternative Approaches to Measurement of Ground Vibrations Due to the Vibratory Roller: A Pilot Study

Monitoring a 28.5 m High Anchored Pile Wall in Gravel Using Various Methods

A novel radar-based system for underground mine wall stability monitoring

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