Quantifying progressive failure of micro-anchored fiber optic cable–sand interface via high-resolution distributed strain sensing

2020 ◽  
Vol 57 (6) ◽  
pp. 871-881 ◽  
Author(s):  
Cheng-Cheng Zhang ◽  
Hong-Hu Zhu ◽  
Su-Ping Liu ◽  
Bin Shi ◽  
Gang Cheng
Keyword(s):  
High Resolution ◽  
Fiber Optic ◽  
Progressive Failure ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Deformation Monitoring ◽  
Shear Stresses ◽  
Fiber Optic Cable ◽  
Geotechnical Monitoring ◽  
Inclusion Interaction

Distributed fiber optic sensing (DFOS) is gaining increasing interest in geotechnical monitoring. By using soil-embedded fiber optic cables, strain profiles as well as deformation patterns of geotechnical infrastructures can be captured. Probing the fiber optic cable–soil interfacial behavior is vital to the advancement of DFOS-based geotechnical monitoring and our understanding of the soil–inclusion interaction mechanism. To this aim, laboratory pullout tests were performed to investigate the progressive failure of the interface between micro-anchored cables and the surrounding sand. High-resolution strain profiles recorded using Brillouin optical time-domain analysis (BOTDA) not only elucidated the influence of anchorage on strain measurements, but also allowed the classical soil–inclusion interaction problem to be studied in detail. Interfacial shear stresses calculated from step-like strain profiles provided clear evidence of the contribution of each micro-anchor to the pullout resistance. The cable–soil contact is a combination of overall bonding and point fixation depending on the level of mobilized interfacial shear stress, and therefore the validity of measured strains is correlated to a three-stage process of interface failure. This study also shows that installing heat-shrink tubes on the fiber optic cable is a rapid, low-cost, effective approach to make an anchored DFOS system for deformation monitoring of earth structures.

Photoelastic Determination of Interfacial Shear Stresses in Model Composites

2007 ◽  
Vol 334-335 ◽  
pp. 289-292 ◽  
Author(s):  
F.M. Zhao ◽  
Z. Liu ◽  
F.R. Jones
Keyword(s):  
Glass Fibre ◽  
Mechanical Response ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Interfacial Shear ◽  
Shear Stresses ◽  
Contour Maps ◽  
Phase Stepping ◽  
Fibre Matrix

Phase-stepping photoelasticity has been used to study the fragmentation of an E-glass fibre in epoxy resin and examine quantitatively the effect of a transverse matrix crack on the stress transfer at an interphase. Unsized glass fibre was coated by plasma polymerisation with a crosslinked conformal film of 90% acrylic acid and 10% 1,7-octadiene. The micro-mechanical response at the fibre-matrix interphase and in the adjacent matrix has been described in detail using contour maps of fringe order. From these, the interfacial shear stress profiles at fibre-break have been calculated.

Experimental analysis of interfacial shear stress and electrical resistance of indium tin oxide-coated polyethylene terephthalate films for a whole folding test

2019 ◽  
Vol 36 (2) ◽  
pp. 130-150 ◽  
Author(s):  
Bor-Jiunn Wen ◽  
Shih-An Huang ◽  
Ting-Yu Tseng
Keyword(s):  
Shear Stress ◽  
Polyethylene Terephthalate ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Electrical Resistance ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Shear Stresses ◽  
Interface Shear ◽  
Conductive Substrate

The purpose of this study is to analyze the performance of the flexible conductive substrate by interfacial shear stress. This study performed automatic liquid-crystal modulating common-path interferometry (LMCI) optical inspections on 125-µm polyethylene terephthalate (PET) substrates having indium tin oxide (ITO) coating thicknesses of 80 nm, 160 nm, and 230 nm. The nonlinear characteristic of the stress-optical coefficient of the ITO material is obtained using LMCI. To validate the performance of the flexible conductive substrate, this study has utilized an automatic sliding-folding testing platform (ASTP) for a whole-folding test. Eventually, this study successfully has utilized interface shear stresses to validate the performance of the flexible conductive substrate depended on the different thicknesses of the conductive layers for whole-folding test by using LMCI and ASTP. According to the measurement results, as the folding radii decrease and the ITO thicknesses of ITO-coated PET substrates increase, the changes of interfacial shear stresses increase in compressive direction and the change-rates of electrical resistance of ITO-coated PET substrate also increase. Therefore, the interfacial shear stress measurement and analysis results depicted on flexible conductive substrates provide a validation for improving the manufacturing process and for reducing process residual stresses.

Protection of Pipelines Uncovered in Crossing River: A Case Study

2013 ◽  
Author(s):  
Priscila Pereira Teixeira ◽  
Wanderley Camargo Russo ◽  
João Luiz Torralbo Quintana ◽  
Ricardo Hoff
Keyword(s):  
Fiber Optic ◽  
Fiber Optic Cable ◽  
Bathymetric Survey ◽  
Critical Situation ◽  
Geotechnical Monitoring ◽  
Low Visibility ◽  
Anthropic Influence ◽  
One Year ◽  
Flooded Areas

To ensure the integrity of pipelines in failure mode Geotechnical, TRANSPETRO and the TBG perform underwater inspections of pipelines in the main crossings of rivers, lakes, dams, canals and permanently flooded areas. The inspections are designed to locate guideline and measure the covering the pipelines from the margins and underwater depth, identify any exposure of the pipelines, map the occurrences of blocks of rock or debris on the channel and evaluate the anthropic influence on stability of the sections inspected. Among the crossings rivers inspected, in the Atibaia V, with approximately 27.3 m in length, was observed a high erosive potential, which resulted in the loss cover of 3 (three) pipelines of crossing river, besides the fiber optic cable. The lengths uncovered resulted in approximately 33.0 m, with suspended pipes, damage in the concrete jacket and presence of blocks of rocks in the channel. The pipeline in the most critical situation went vain of 6.0 m, with gap up to 0,2 m in relation the background. The crossing river was studied with bathymetric survey and designed cover the pipelines with mechanical protection and anti-erosive. The pipes were supported with sacks of granular material, sequentially, the margins and pipelines were protected with geotextile filled with concrete, installed with the help of divers. The working conditions of 4.0 m depth, currents of up to 0.8 m/s, temperature and low visibility waters were challenges overcome during execution, in which the divers took turns in short periods. Due to the characteristics of the bedrock, the blankets went stylized and stitched on the field by the team, with dimensions taken on site. After positioning the blankets in the background began the underwater concreting, which occurred in stages monitored by the volume pumped and divers strategically placed. The crossing river was re-inspected approximately 1 (one) year after their stabilization and was found in good conditions. The occurrence improved the procedures for geotechnical monitoring and treatment of pipelines uncovered in crossings rivers, being who the efficiency and safety of the work performed currently serve as a reference for the design of similar works.

Pipeline Monitoring With Geotechnical Optical Fiber

2017 ◽  
Author(s):  
Christian Silva ◽  
Fabien Ravet
Keyword(s):  
Optical Fiber ◽  
Fiber Optic ◽  
Large River ◽  
Temperature Sensing ◽  
Fiber Optic Cable ◽  
Right Of Way ◽  
Geotechnical Monitoring ◽  
Pipeline Monitoring ◽  
Operating Company ◽  
Abnormal Temperature

The 408 km × 34" PERULNG pipeline (operated by Hunt LNG Operating Company) is monitored in its first 62 km by a geotechnical fiber optic cable, since these first 62 km are exposed to major geohazard threats such as landslides, large river crossings, high slopes, bofedales, etc. The fiber optic cable geotechnical monitoring relies on the measurement of strain and temperature in the pipeline right-of-way. Due to the continuous and real-time monitoring of the duct, it was possible to detect a tension cracking near KP 25 + 600 as an abnormal temperature change was captured by the temperature sensing cable; also near KP 27 + 900 and KP 34 + 750 unusual cable stresses were detected which announced landslides of the rotational type in both locations. In these three cases, protection decisions could be taken to secure pipeline’s integrity.

Role of Fiber-Matrix Interfacial Shear Stress on the Toughness of Reinforced Oxide Matrix Composites

1988 ◽  
Vol 120 ◽  
Author(s):  
Raj N. Singh
Keyword(s):  
Shear Stress ◽  
Interfacial Shear Stress ◽  
Ceramic Matrix Composites ◽  
Interfacial Shear ◽  
Matrix Cracking ◽  
Shear Stresses ◽  
Matrix Composites ◽  
Zircon Ceramic ◽  
Strength And Toughness

AbstractMullite and zircon ceramic matrix composites uniaxially reinforced with as-supplied and BN-coated silicon carbide filaments were fabricated. The filament-matrix interfacial shear stresses were measured by a modified indentation technique and mechanical properties were determined in flexure mode. Significant improvements in strength and toughness were observed for the composites in comparison to monolithic mullite and zircon ceramics. Lower filament-matrix interfacial shear stresses were measured in composites with BN-coated filaments than in composites containing as-supplied filaments. The influence of filament-matrix interfacial shear stress on the critical stress for first matrix cracking, maximum composite strength, and toughness of the composites were studied.

Fiber optic cable-based high-resolution, long-distance VGA extenders

2013 ◽  
Author(s):  
Jin-Geun Rhee ◽  
Iksoo Lee ◽  
Heejoon Kim ◽  
Sungjoon Kim ◽  
Yeon-Wan Koh ◽  
...  
Keyword(s):  
High Resolution ◽  
Fiber Optic ◽  
Fiber Optic Cable ◽  
Long Distance

Carcass Tearing in Flexible Pipes

2015 ◽  
Author(s):  
Rasmus Hansen ◽  
Anders Lyckegaard ◽  
Christian Cappeln ◽  
Dag Mcgeorge ◽  
Nils Sødahl ◽  
...  
Keyword(s):  
Shear Stress ◽  
Thermal Loading ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Design Parameters ◽  
Engineering Practice ◽  
Shear Stresses ◽  
Interfacial Slip ◽  
Analytical Expression ◽  
Flexible Pipes

This paper presents a novel model of carcass tearing in flexible pipes. The model is based on a simple parameterization of the pipe design in terms of isotropic layers, together forming the composite pipe structure. The model allows evaluations of interfacial shear stresses between the inner pipe layers, as well as axial normal stress and strain levels in response to gravitational and thermal loading. Interfacial slip of a given interface, i.e. axial sliding of adjacent layers relative to each other, is accounted for by introducing a maximal possible value of the interfacial shear stress for a given interface, amounting to a static friction capacity. The model shows how a cut-off of the shear stress at the shear stress capacity implies an interfacial slip, which is followed by a significant increase in axial strain of the carcass layer. Detailed quantitative results of the model are presented for a particular 11.5 inch K-carcass riser design. In order to improve engineering practice, an analytical expression of the governing shear stress is derived in terms of the gravitational and thermal loads. This analytical expression is easily applied for particular design evaluations. The model directs attention to critical design parameters related to the carcass tearing failure mode and thereby supports continued safety in the design and operation of flexible pipes from a carcass tearing perspective.

The ROLE OF CHINA-PAK ECONOMIC CORRIDOR (CPEC) IN LOGISTIC SYSTEM OF PAKISTAN’S AND CHINA’S

2019 ◽  
Vol 6 (1) ◽  
pp. 48-50
Author(s):  
Ikram Uddin
Keyword(s):  
Persian Gulf ◽  
Lead Time ◽  
Fiber Optic ◽  
Delivery Time ◽  
Fiber Optic Cable ◽  
Total Cost ◽  
Economic Complexity ◽  
Shipping Cost ◽  
The Impact

This study will explain the impact of China-Pak Economic Corridor (CPEC) on logistic system of China and Pakistan. This project is estimated investment of US $90 billion, CPEC project is consists of various sub-projects including energy, road, railway and fiber optic cable but major portion will be spent on energy. This project will start from Kashgar port of china to Gwadar port of Pakistan. Transportation is sub-function of logistic that consists of 44% total cost of logistic system and 20% total cost of production of manufacturing and mainly shipping cost and transit/delivery time are critical for logistic system. According to OEC (The Observing Economic Complexity) currently, china is importing crude oil which 13.4% from Persian Gulf. CPEC will china for lead time that will be reduced from 45 days to 10 days and distance from 2500km to 1300km. This new route will help to china for less transit/deliver time and shipping cost in terms of logistic of china. Pakistan’s transportation will also improve through road, railway and fiber optic cabal projects from Karachi-Peshawar it will have speed 160km per hour and with help of pipeline between Gwadar to Nawabshah gas will be transported from Iran. According to (www.cpec.inf.com) Pakistan logistic industry will grow by US $30.77 billion in the end of 2020.

Optical data signals in fiber optic communication links with fading

2019 ◽  
pp. 94-104
Author(s):  
I. Juwiler ◽  
I. Bronfman ◽  
N. Blaunstein
Keyword(s):  
Spectral Efficiency ◽  
Fiber Optic ◽  
Fiber Optic Cable ◽  
Optical Signals ◽  
Dispersion Properties ◽  
Optical Cable ◽  
Time Dispersion ◽  
Communication Links ◽  
Fiber Optic Communication ◽  
Optic Communication

Introduction: This article is based on the recent research work in the field of two subjects: signal data parameters in fiber optic communication links, and dispersive properties of optical signals caused by non-homogeneous material phenomena and multimode propagation of optical signals in such kinds of wired links.Purpose: Studying multimode dispersion by analyzing the propagation of guiding optical waves along a fiber optic cable with various refractive index profiles of the inner optical cable (core) relative to the outer cladding, as well as dispersion properties of a fiber optic cable due to inhomogeneous nature of the cladding along the cable, for two types of signal code sequences transmitted via the cable: return-to-zero and non-return-to-zero ones.Methods: Dispersion properties of multimode propagation inside a fiber optic cable are analyzed with an advanced 3D model of optical wave propagation in a given guiding structure. The effects of multimodal dispersion and material dispersion causing the optical signal delay spread along the cable were investigated analytically and numerically.Results: Time dispersion properties were obtained and graphically illustrated for two kinds of fiber optic structures with different refractive index profiles. The dispersion was caused by multimode (e.g. multi-ray) propagation and by the inhomogeneous nature of the material along the cable. Their effect on the capacity and spectral efficiency of a data signal stream passing through such a guiding optical structure is illustrated for arbitrary refractive indices of the inner (core) and outer (cladding) elements of the optical cable. A new methodology is introduced for finding and evaluating the effects of time dispersion of optical signals propagating in fiber optic structures of various kinds. An algorithm is proposed for estimating the spectral efficiency loss measured in bits per second per Hertz per each kilometer along the cable, for arbitrary presentation of the code signals in the data stream, non-return-to zero or return-to-zero ones. All practical tests are illustrated by MATLAB utility.

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