The Use of Fibre Optic Sensors to Monitor Pipeline Response to Tunnelling

Vorster, Teb; Soga, Kenichi; Mair, RJ; Bennett, P.J.; Klar, Assaf; Choy, C K

doi:10.1061/40803(187)33

Cited by 29 publications

(18 citation statements)

References 2 publications

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“…These standard fibers are normally used indoors as the strains in the core caused by the larger temperature variations outdoors are undesirable in telecommunication applications. However, the use of single-fiber cable has been implemented rather successfully for monitoring deformation of underground tunnels 13, 14 as well as monitoring buried pipeline deformation using the ribbon-fiber cable 8 .…”

Section: Optical Cablesmentioning

confidence: 99%

“…There are many examples of distributed strain measurements being applied in various civil or geotechnical engineering applications, e.g. (i) in piled foundations [5][6][7] , (ii) pipelines 8,9 , (iii) earth retaining structures [10][11] , and (iv) tunnels [12][13][14] . Despite numerous field trials broadly reporting successful implementation of BOTDR instrumentation on a wide range of geotechnical infrastructures, little attention has been made on how the temperature compensation process was applied to their strain readings.…”

Section: Introductionmentioning

confidence: 99%

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Temperature and strain sensing techniques using Brillouin optical time domain reflectometry

Mohamad

2012

SPIE Proceedings

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Distributed strain sensing based on Brillouin Optical Time Domain Reflectometry (BOTDR) is seen as one of the most promising monitoring tools for assessing the performance of civil and geotechnical structures. Due to the distributed nature of fiber optic sensor, BOTDR not only useful to monitor the structures deformation in terms of global behavior, but also effectively detects anomalies in localized scale. Since the sensor has the ability to measure strain and temperature simultaneously, it is important that methods to separate the temperature effects are fully understood. Four known methods used to compensate temperature from BOTDR strain readings are briefly reviewed. Regardless of what method being used, this paper aims to clarify the importance of firstly calibrating the thermal characteristic of optical cables and determine the coefficient thermal expansion of the measurement host or structure. Example of BOTDR thermal measurement of an earth retaining structure is presented.

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Section: Optical Cablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature and strain sensing techniques using Brillouin optical time domain reflectometry

Mohamad

2012

SPIE Proceedings

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“…In hydraulic structures such as embankments and dams, tensile cracks usually provide preferential paths for water transport, increase permeability, and may lead eventually to catastrophic failure [3][4][5]. In urban areas, the differential surface settlement caused by tunnel construction and deep excavation may induce shallow tensile cracks on ground surface, which pose a potential hazard to nearby buildings and structures [6].…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional simulations of tensile cracks in geomaterials by coupling meshless and finite element method

Peng¹,

Wu²,

Zhang

2014

Num Anal Meth Geomechanics

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Failure in geotechnical engineering is often related to tension-induced cracking in geomaterials. In this paper, a coupled meshless method and FEM is developed to analyze the problem of three-dimensional cracking. The radial point interpolation method (RPIM) is used to model cracks in the smeared crack framework with an isotropic damage model. The identification of the meshless region is based on the stress state computed by FEM, and the adaptive coupling of RPIM and FEM is achieved by a direct algorithm. Mesh-bias dependency, which poses difficulties in FEM-based cracking simulations, is circumvented by a crack tracking algorithm. The performance of our scheme is demonstrated by two numerical examples, that is, the four-point bending test on concrete beam and the surface cracks caused by tunnel excavation. progress in the field of smeared crack modeling, some major issues still remain unsolved. Two of these important issues are the local remeshing and the modeling of complex three-dimensional crack topology.As crack is represented by strain localization in the crack band, the crack propagation is assumed to proceed elementwise in the smeared crack model. A conundrum in problems involving strain localization is the mesh dependence of the numerical solutions. Although the mesh size dependence can be mitigated by making use of the fracture energy conservation, the element size still has some influence on the numerical result. If a relatively large element size is used, which is more likely in three-dimensional problems, the crack initiation and propagation path cannot be properly captured. Therefore, the mesh used in crack simulation should be fine enough to obtain a satisfactory result. Because of the requirement of node connectivity, however, the three-dimensional local remeshing in FEM can be a cumbersome work. Some recently developed meshless methods need only node information for the establishment of the system of equations, thus are advantageous in adaptive analysis and crack simulation [13,14]. However, the computational efficiency of most meshless methods is rather low compared with FEM. Obviously, a coupling of these two methods may offer the optimal choice by making full use of their advantages [15,16]. Among the meshless methods, the radial point interpolation method (RPIM) possesses the property of the Kronecker delta function, which makes the enforcement of essential boundary condition and the coupling with FEM feasible [17,18]. Wang et al. [19] proposed a direct coupling approach for the simulation of crack propagation in rock and compacted clay, in which the crack region is treated by RPIM, while FEM is used in the rest of the area. In the coupling method, a crucial issue is the identification of the crack region in order to decide where RPIM should be used.Another problem is the modeling of cracks with complex topology. Within the smeared crack framework, the mesh-bias dependency makes it difficult to handle curved cracks properly because the crack propagation path is found to be strongly affected ...

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“…Having originated from the telecommunications technology, the BOTDR has successfully emerged to be a competent monitor of earthen structures or long structures, e.g. the deformation of a levee [4] or the displacement of a pipeline [5]. On the other hand, BOCDA is developed to detect even a tiny strain change within the range of the limited measurement length, thanks to its high spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Application of Brillouin optical correlation domain analysis for crack identification in concrete structure

Imai

Miura

2013

Photonic Sens

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This paper investigates the application of distributed optical fiber strain sensors to civil engineering structures, because no other tool can satisfactorily detect the location of the unpredictable phenomenon. In fact, the locations of cracks in the concrete structure are unknown a priori; therefore, a fully distributed sensor is necessary to detect them. The Brillouin optical correlation domain analysis (BOCDA), which offers high spatial resolution by using stimulated Brillouin scattering along the whole length of the optical fiber, is used in a wide range of civil engineering applications, and the same has undergone significant development over the last decade. In this paper, it is demonstrated how a BOCDA-based strain sensor can be employed to monitor cracks in concrete. Crack monitoring on the surface of the concrete member provides useful information for evaluating stiffness and durability of the structure, particularly for early detection of tiny cracks, which is essential for preventing crack growth and dispersion. The crack-induced strain distribution was analytically investigated, and it was proved that BOCDA can identify even a small crack before its visual recognition by a beam test. Moreover, periodical crack monitoring was successfully executed on a pedestrian deck for five years.

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The Use of Fibre Optic Sensors to Monitor Pipeline Response to Tunnelling

Cited by 29 publications

References 2 publications

Temperature and strain sensing techniques using Brillouin optical time domain reflectometry

Temperature and strain sensing techniques using Brillouin optical time domain reflectometry

Three‐dimensional simulations of tensile cracks in geomaterials by coupling meshless and finite element method

Application of Brillouin optical correlation domain analysis for crack identification in concrete structure

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