Load-Independent Characterization of Plate Foundation Support Using High-Resolution Distributed Fiber-Optic Sensing

Asmus Skar; Assaf Klar; Eyal Levenberg

doi:10.3390/s19163518

Load-Independent Characterization of Plate Foundation Support Using High-Resolution Distributed Fiber-Optic Sensing

Sensors ◽

10.3390/s19163518 ◽

2019 ◽

Vol 19 (16) ◽

pp. 3518 ◽

Cited By ~ 3

Author(s):

Asmus Skar ◽

Assaf Klar ◽

Eyal Levenberg

Keyword(s):

High Resolution ◽

Mechanical Model ◽

Fiber Optic ◽

Soil Parameters ◽

Soil Reaction ◽

Model Parameters ◽

Strain Sensing ◽

Soil Response ◽

Monitoring Strategies

The evaluation of soil reaction in geotechnical foundation systems such as concrete pavements, mat- and raft foundations is a challenging task, as the process involves both the selection of a representative mechanical model (e.g., Winkler, Continuum, Pasternak, etc.) and identify its prevailing parameters. Moreover, the support characteristics may change with time and environmental situation. This paper presents a new method for the characterization of plate foundation support using high-resolution fiber-optic distributed strain sensing. The approach involves tracking the location of distinct points of zero and maximum strains, and relating the shift in their location to the changes in soil reaction. The approach may allow the determination of the most suited mechanical model of soil representation as well as model parameters. Routine monitoring using this approach may help to asses the degradation of the subsoil with time as part of structural health monitoring strategies. In this paper, fundamental expressions that relate between the location of distinct strain points and the variation of soil parameters were developed based on various analytical foundation support models. Finally, as an initial validation step and to underpin the idea basics, the proposed method was successfully demonstrated on a simple mechanical setup. It is shown that the approach allows for load-independent characterization of the soil response and, in that sense, it is superior to common identification methods.

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High-resolution absolute frequency referenced fiber optic sensor for quasi-static strain sensing

Applied Optics ◽

10.1364/ao.49.004029 ◽

2010 ◽

Vol 49 (21) ◽

pp. 4029 ◽

Cited By ~ 44

Author(s):

Timothy T.-Y. Lam ◽

Jong H. Chow ◽

Daniel A. Shaddock ◽

Ian C. M. Littler ◽

Gianluca Gagliardi ◽

...

Keyword(s):

High Resolution ◽

Fiber Optic ◽

Fiber Optic Sensor ◽

Strain Sensing ◽

Absolute Frequency ◽

Static Strain ◽

Optic Sensor

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A mechanical model to interpret distributed fiber optic strain measurement at displacement discontinuities

Structural Health Monitoring ◽

10.1177/1475921720964183 ◽

2020 ◽

pp. 147592172096418

Author(s):

Shenghan Zhang ◽

Han Liu ◽

Jeffrey Cheng ◽

Matthew J DeJong

Keyword(s):

Strain Measurement ◽

Mechanical Model ◽

Fiber Optic ◽

A Priori ◽

Shear Stiffness ◽

Displacement Discontinuity ◽

Multiple Cracks ◽

Strain Sensing ◽

Cable Properties ◽

Discontinuous Displacement

Distributed fiber optic (strain) sensing, which provides the unique advantage of sensing damage (e.g. cracking) at locations that are not known a priori, has been increasingly used in civil engineering. Quantitative crack measurement requires the translation of a discontinuous displacement field at the crack to a continuous strain deformation in the fiber. The main purpose of this article is to develop a mechanical model to explain the fiber deformation in the presence of a displacement discontinuity. The proposed mechanical model is validated with experimental results from cable calibration tests and concrete cracking tests. The model is extended to simulate the effects of multiple closely spaced cracks on fiber optic strain measurement, and this model is used to create an algorithm to automatically distinguish multiple cracks in distributed fiber optic (strain) sensing strain distributions. Using the model and two shape parameters, kurtosis and standard variation, the effects of cable properties (i.e. shear stiffness between cable and fiber, cable radius, elastic modulus, and interface cohesion) on the shape of fiber optic strain distributions across cracks are also quantified. The results provide an indication of beneficial cable properties for various measurement objectives.

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Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074768 ◽

1983 ◽

Vol 41 ◽

pp. 194-195

Author(s):

D. F. Blake ◽

L. F. Allard ◽

D. R. Peacor

Keyword(s):

High Resolution ◽

Marine Invertebrates ◽

Sea Urchins ◽

Structural Features ◽

Sea Stars ◽

High Resolution Tem ◽

Relationship Of ◽

The Relationship ◽

Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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High-resolution electron microscopy of nanostructured materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137239 ◽

1995 ◽

Vol 53 ◽

pp. 172-173

Author(s):

M. José-Yacamán

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Grain Boundaries ◽

Nanostructured Materials ◽

High Resolution Electron Microscopy ◽

Hrem Image ◽

Small Particles ◽

Resolution Electron ◽

Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

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High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155438 ◽

1989 ◽

Vol 47 ◽

pp. 692-693

Author(s):

H. Takaoka ◽

M. Tomita ◽

T. Hayashi

Keyword(s):

High Resolution ◽

Oxygen Concentration ◽

Silicon Layer ◽

Detailed Structure ◽

Electron Microscopic ◽

Cross Sectional ◽

Transmission Electron ◽

Doped Silicon ◽

Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

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HRTEM simulation of interfacial structure in amorphous multilayers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154305 ◽

1989 ◽

Vol 47 ◽

pp. 466-467

Author(s):

Margaret L. Sattler ◽

Michael A. O'Keefe

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Cross Section ◽

High Resolution Electron Microscopy ◽

Interfacial Structure ◽

Multilayer Sample ◽

Resolution Electron ◽

Multilayered Materials ◽

Simulated Images

Multilayered materials have been fabricated with such high perfection that individual layers having two atoms deep are possible. Characterization of the interfaces between these multilayers is achieved by high resolution electron microscopy and Figure 1a shows the cross-section of one type of multilayer. The production of such an image with atomically smooth interfaces depends upon certain factors which are not always reliable. For example, diffusion at the interface may produce complex interlayers which are important to the properties of the multilayers but which are difficult to observe. Similarly, anomalous conditions of imaging or of fabrication may occur which produce images having similar traits as the diffusion case above, e.g., imaging on a tilted/bent multilayer sample (Figure 1b) or deposition upon an unaligned substrate (Figure 1c). It is the purpose of this study to simulate the image of the perfect multilayer interface and to compare with simulated images having these anomalies.

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