scholarly journals A Method of Monitoring the Cross-Section Deformation of Tunnels Using the Strain Data from the Fully Distributed Optical Fibre Sensors

2021 ◽  
Vol 1203 (2) ◽  
pp. 022125
Author(s):  
Guohao Ma ◽  
Shaoyi Zhang ◽  
Hu Li ◽  
Panshan Li ◽  
Yang Liu
Keyword(s):  
Correlation Coefficient ◽  
Cross Section ◽  
Longitudinal Strain ◽  
High Density ◽  
Sensing Technology ◽  
Deformation Law ◽  
Strain Data ◽  
Optical Fiber Sensing ◽  
The Cross ◽  
Distributed Optical Fiber

Abstract Fully distributed optical fiber sensing technology allows the high-density strain to measure the overall curvature and cross-section deformation of tunnels. However, there are few studies on the use of longitudinal strain along the tunnel to measure the cross-section convergence deformation, and the method of obtaining the strain along the tunnel loop is costly. To address this issue, a method of monitoring the cross-section deformation of tunnels using the strain data is proposed. First, a model of the relationship between strain and deformation in tunnels is constructed to obtain the overall settlement using the longitudinal strain. Second, based on the finite element method (FEM), the deformation law about the strain measured points and non-measured points on the cross-section of the tunnel is proposed, and on this basis, the correlation coefficient is presented. Using the product of overall settlement and correlation coefficient, the cross-section deformation at non-measured points is obtained. The results of numerical examples shown that the proposed method can effectively expand the monitoring scale and realize high-density cross-section deformation measurement of tunnels.

scholarly journals Experimental Study on Deformation Monitoring of Bored Pile Based on BOTDR

2019 ◽  
Vol 9 (12) ◽  
pp. 2435 ◽  
Author(s):  
Lei Gao ◽  
Chuan Han ◽  
Zhongquan Xu ◽  
Yingjie Jin ◽  
Jianqiang Yan
Keyword(s):  
Optical Fiber ◽  
Noise Removal ◽  
Deformation Monitoring ◽  
Optical Time Domain Reflectometer ◽  
Fiber Sensing ◽  
Bored Pile ◽  
Sensing Technology ◽  
Optical Fiber Sensing ◽  
Unbiased Risk ◽  
Distributed Optical Fiber

In order to study the deformation of bored pile, it is necessary to monitor the strain of the pile. The distributed optical fiber sensing technology realizes the integration of sensing and transmission, which is incomparable with traditional point monitoring method. In this paper, the Brillouin optical time domain reflectometer (BOTDR) distributed optical fiber sensing technology is used to monitor the deformation of the bored pile. The raw data monitored by BOTDR is processed by the wavelet basis function, that can perform noise removal processing. Three different methods of noise removal are chosen. Through the processing, the db5 wavelet is used to decompose the deformation data of bored pile monitored by BOTDR into two layers. The decomposed high-frequency signal is denoised by the Stein-based unbiased risk threshold, rigrsure. The decomposed data is smoothed by the translational mean method, and the final data after denoising and smoothing processing is real and reliable. The results of this study will provide data support for the deformation characteristics of bored pile, and also show the advantages of distributed optical fiber sensing technology.

Secondary Development of DiTeSt-STA202 Based on Delphi and Access

2010 ◽  
Vol 36 ◽  
pp. 103-108
Author(s):  
Kuan Fang He ◽  
Ping Yu Zhu ◽  
Xue Jun Li ◽  
D.M. Xiao
Keyword(s):  
Optical Fiber ◽  
Data Processing ◽  
Data Storage ◽  
Secondary Development ◽  
Typical Application ◽  
Sensing Technology ◽  
Optical Fiber Sensing ◽  
Analysis System ◽  
Distributed Optical Fiber ◽  
User Friendly

Distributed optical fiber sensing technology in the dam safety monitoring has been applied. The most typical application is the Swiss distributed optical fiber DiTeSt-STA202 analyzer. The instrument can simultaneously measure the distribution of thousands of points in a fiber strian and temperature, and it is suitable for measurement of objects up to several kilometers, but it’s functions limit to the data acquisition and the most primitive conversion of the strain and temperature without the deeper data processing functions, and the interface is less of user-friendly nature and poor adaptability. In this paper, The secondary development of DiTeSt-STA202 is done by Delphi and ADO technology based on analysis of the data storage types and formats. The data processing and analysis system is achieved in an efficient and accurate way.

Study on the Bearing Mechanism of Squeezed Branch Pile Based on BOTDR

2011 ◽  
Vol 368-373 ◽  
pp. 2065-2070
Author(s):  
Chun De Piao ◽  
Yong Zhao Qu
Keyword(s):  
Soil Layer ◽  
Load Test ◽  
Static Load Test ◽  
Pile Head ◽  
Sensing Technology ◽  
Side Resistance ◽  
Load Carrying ◽  
Optical Fiber Sensing ◽  
Negative Friction ◽  
Distributed Optical Fiber

Based on BOTDR distributed optical fiber sensing technology, this paper studies the variation law of branch pile axial force under the action of pile head loads and the action characteristic of pile side resistance during static load test. The result shows that: the branch of squeezed branch pile, as the major load-carrying object, bears most of the pile head loads and its function gradually emerges with increasing pile head loads. Under the action of pile head loads, the settlement and compression value of branch pile is elevated, which gradually brings about free face between branch and its overlaying soil layer. When the load exceed certain amount, the overlaying soil body of branch cracks under pile-soil interaction, and gradually loses its structural properties, because of which its settlement emerges and negative friction subsequently generated. Thus, during the design of branch pile, one should improve the properties of the soil layer around branch pile, enhance the strength of pile shaft, and lessen pile compressing deformation and settlement, so as to elevate the bearing capacity of branch pile.

Pipeline corrosion and leakage monitoring based on the distributed optical fiber sensing technology

Measurement ◽  
2018 ◽  
Vol 122 ◽  
pp. 57-65 ◽  
Author(s):  
Liang Ren ◽  
Tao Jiang ◽  
Zi-guang Jia ◽  
Dong-sheng Li ◽  
Chao-lin Yuan ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Fiber Sensing ◽  
Sensing Technology ◽  
Optical Fiber Sensing ◽  
Leakage Monitoring ◽  
Distributed Optical Fiber ◽  
Pipeline Corrosion
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