Study of a progressive failure in soil using BEDS

Iten, Michael; Puzrin, Alexander M.; Hauswirth, Dominik; Foaleng-Mafang, Stella; Beugnot, Jean‐Charles; Thévenaz, Luc

doi:10.1117/12.835115

Cited by 12 publications

(9 citation statements)

References 3 publications

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“…The authors have developed a geomechanical model, that can describe progressive failure of long uniaxial structures embedded in sand at the lab scale [17] . With the data of this paper, it will be possible to apply this model to full scale field tests.…”

Section: Discussionmentioning

confidence: 99%

Monitoring of stress distribution along a ground anchor using BOTDA

Iten

Puzrin

2010

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010

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For the understanding of the bearing behavior of a loaded ground anchor, the measuring and monitoring of the stress distribution in the anchor tendon is essential. This paper proposes a novel monitoring ground anchor using embedded optical fibers for the continuous strain assessment along the anchor tendon. In a first step, optical sensors have been integrated into short tendons using different methods and laboratory strain testing was performed on these instrumented tendons. The evaluation of the laboratory testing enabled the design and development of an 8m long monitoring ground anchor for field application. In 2009, this anchor has been placed into a wall supporting an excavation pit and subsequently, anchor pullout test was carried out. The anchor was loaded stepwise up to 470kN, almost reaching its ultimate bearing capacity. Optical measurements were taken successfully at each load step. Comparison of the optical data with data acquired using conventional methods indicated good consistency of the results. To a geotechnical engineer, this proposed monitoring anchor provides a powerful tool for the measuring of the pullout load, the anchor head displacement and the load distribution in the anchor tendon.

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Section: Discussionmentioning

confidence: 99%

Monitoring of stress distribution along a ground anchor using BOTDA

Iten

Puzrin

2010

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010

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“…In the present study, the evolution of strain distribution captured by the BOTDA demodulator further confirmed this phenomenon. Compared with a previous study reported by Iten et al 31,. our focus was on examining the validity of measured data during the course of progressive interface failure, which enabled us to identify and propose three working states of a soil-embedded strain sensing fibre (Fig.…”

Section: Discussionmentioning

confidence: 53%

Role of the interface between distributed fibre optic strain sensor and soil in ground deformation measurement

Zhang

Zhu

Shi

2016

Sci Rep

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Recently the distributed fibre optic strain sensing (DFOSS) technique has been applied to monitor deformations of various earth structures. However, the reliability of soil deformation measurements remains unclear. Here we present an integrated DFOSS- and photogrammetry-based test study on the deformation behaviour of a soil foundation model to highlight the role of strain sensing fibre–soil interface in DFOSS-based geotechnical monitoring. Then we investigate how the fibre–soil interfacial behaviour is influenced by environmental changes, and how the strain distribution along the fibre evolves during progressive interface failure. We observe that the fibre–soil interfacial bond is tightened and the measurement range of the fibre is extended under high densities or low water contents of soil. The plastic zone gradually occupies the whole fibre length when the soil deformation accumulates. Consequently, we derive a theoretical model to simulate the fibre–soil interfacial behaviour throughout the progressive failure process, which accords well with the experimental results. On this basis, we further propose that the reliability of measured strain can be determined by estimating the stress state of the fibre–soil interface. These findings may have important implications for interpreting and evaluating fibre optic strain measurements, and implementing reliable DFOSS-based geotechnical instrumentation.

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“…We have proposed a theoretical method for evaluating quantitatively the mechanical coupling between a buried FO cable and its surroundings when the DSS technology is employed to record Earth materials deformation. Previous coupling studies (e.g., Iten et al, 2009; Zhang et al, 2016) have primarily focused on the ground‐cable interface shear failure criterion (ASTM F3079‐14, 2014), which does not allow to recover the actual amount of deformation from fiber optics‐measured strains. By contrast, our approach presented herein considers both the interface shear failure and the efficiency of strain transfer from ground to cable and thus allows the quantification of how much of the ground movement‐induced strain is transferred to the sensing element through interface shear.…”

Section: Discussionmentioning

confidence: 99%

“…However, the strain extracted from the demodulated signal is not fully representative of that experienced by the ground, due primarily to the interface slippage and/or the interface shear transfer within the ground‐to‐cable system (Zhang et al, 2018). Previous research has examined the ground‐cable interface shear behavior under the pullout scenario, with particular emphasis on the progressive failure of the interface (Iten et al, 2009; Zhang et al, 2016). The deformation of an FO cable is compatible with the surrounding media provided no relative slippage occurs (governed by the shear strength criterion), as suggested by a current international standard (ASTM F3079‐14, 2014).…”

Section: Introductionmentioning

confidence: 99%

Toward Distributed Fiber‐Optic Sensing of Subsurface Deformation: A Theoretical Quantification of Ground‐Borehole‐Cable Interaction

et al. 2020

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Fiber‐optic sensing is emerging as a superior means for distributed strain sensing of the subsurface. The ability of an embedded fiber‐optic cable to capture accurate strain profiles depends on the degree of rigid mechanical coupling between the ground and the cable. However, a current challenge in this field is to determine the actual level of ground deformation from strain signatures sensed by the cable deployed in the subsurface; addressing this issue has been hampered by the lack of suitable theoretical methods. Here we propose a two‐step ground‐cable coupling evaluation procedure, whereby we develop analytical formulations to quantify the interaction and interface shear transfer of a ground‐borehole‐cable system. We constrain key model parameters using a data set acquired with a fiber optics‐instrumented borehole for monitoring groundwater‐related sediment compaction. Extensive parametric analyses reveal that increasing the backfill modulus and cable gauge length or decreasing the borehole radius and cable stiffness can improve the quality of strain transferred to the cable from the ground; the effect of ground properties is comparably insignificant. Further, we develop design charts and tables at designated transfer thresholds to facilitate the development and field deployment of fiber sensing elements. Taken together, the theoretical quantification of ground‐cable coupling should improve the state‐of‐the‐art performance of distributed fiber‐optic strain sensing for subsurface ground movements detection and monitoring.

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Study of a progressive failure in soil using BEDS

Cited by 12 publications

References 3 publications

Monitoring of stress distribution along a ground anchor using BOTDA

Monitoring of stress distribution along a ground anchor using BOTDA

Role of the interface between distributed fibre optic strain sensor and soil in ground deformation measurement

Toward Distributed Fiber‐Optic Sensing of Subsurface Deformation: A Theoretical Quantification of Ground‐Borehole‐Cable Interaction

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