scholarly journals Experimental Study on Slope Deformation Monitoring Based on a Combined Optical Fiber Transducer

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Yong Zheng ◽  
Dong-Yan Liu ◽  
Zheng-Wei Zhu ◽  
Hong-Lin Liu ◽  
Bang Liu
Keyword(s):  
Optical Fiber ◽  
Empirical Formula ◽  
Large Scale ◽  
Base Material ◽  
Optical Loss ◽  
Deformation Monitoring ◽  
Landslide Monitoring ◽  
Sandy Clay ◽  
Measured Displacement ◽  
Clay Slopes

Landslide monitoring is very important in predicting the behavior of landslides, thereby ensuring environment, life, and property safety. On the basis of our previous studies, a novel combined optic fiber transducer (COFT) for landslides monitoring and the related analysis methods are presented. Based on the principles of optical fiber microbending loss, the empirical formula of the shearing displacement of sliding body versus optical loss was established through a stretching test of optical fiber bowknot. Then the COFT grouting direct shearing tests, a large-scale landslide model test, and numerical modeling verification with FLAC3D are carried out. According to the results, the initial measurement precision of the designed COFT in sandy clay is 1 mm; its monitoring sliding distance is larger than 26.5 mm. The calculated values based on empirical formula are in good agreement with the laboratory tests and numerical simulation results. When the ratio of cement and sand in mortar is 1 : 5, the error between the calculated displacement and the measured displacement of sliding surface is the smallest. The COFT with expandable polystyrene (EPS) as its base material performs better in monitoring sandy clay slopes because both the error and the mean square deviation of the empirical formula are smaller.

scholarly journals New improvement of the combined optical fiber transducer for landslide monitoring

2014 ◽  
Vol 14 (8) ◽  
pp. 2079-2088 ◽  
Author(s):  
Z.-W. Zhu ◽  
Q.-Y. Yuan ◽  
D.-Y. Liu ◽  
B. Liu ◽  
J.-C. Liu ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Shear Test ◽  
Base Material ◽  
Time Domain Reflectometry ◽  
Fourth Generation ◽  
Movement Direction ◽  
Landslide Monitoring ◽  
Third Generation ◽  
The Third ◽  
Sliding Distance

Abstract. Landslide monitoring is important in predicting the behavior of landslides, thereby ensuring environmental, life, and property safety. On the basis of our previous studies, we conducted the double shear test by using a third-generation optical fiber transducer that uses expandable polystyrene (EPS) as base material. However, the third-generation transducer has poor performance when cohesive force is present between the grout and capillary stainless steel pipe of the transducer. Thus, the fourth-generation optical fiber transducer was invented. Similar to the third-generation transducer, the fourth-generation transducer also used EPS as its base material. Single shear test was conducted on the fourth-generation transducer after being grouted with cement mortar (1 : 1 mix ratio). The micro-bend loss mechanism of the optical fiber was considered, and the optical time domain reflectometry instrument was used. The fact that the loss sequence of optical fibers subjected to loading is different at various locations is found. The relationship of the loading-point displacement vs. optical fiber sliding distance and optical loss were measured. Results show that the maximum initial measurement precision of the newly proposed device is 1 mm, the corresponding sliding distance is 21 mm, and the dynamic range is 0–20 mm. The fourth-generation transducer can measure the movement direction of loadings, thus making this transducer applicable for landslide monitoring.

scholarly journals Early Identifying and Monitoring Landslides in Guizhou Province with InSAR and Optical Remote Sensing

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Genger Li ◽  
Bo Hu ◽  
Hui Li ◽  
Feng Lu
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Large Scale ◽  
Surface Deformation ◽  
Satellite Image ◽  
Deformation Monitoring ◽  
Guizhou Province ◽  
Landslide Monitoring ◽  
Optical Remote Sensing ◽  
Monitoring Method

The topography and landforms of Guizhou Province in China are complicated, and the climatic conditions of heavy precipitation make landslide disasters in Guizhou Province occur frequently. To avoid damage to people’s lives and economic property caused by disasters, a reliable early landslide identification method and landslide monitoring method are urgently needed. Traditional landslide identification and monitoring methods have limitations. InSAR technology has unique advantages in large-scale landslide identification and monitoring, but landslide identification results based on a single deformation value are one-sided. Therefore, this paper uses Sentinel-1A radar satellite image data and uses InSAR technology and optical remote sensing technology to carry out large-scale surface deformation monitoring and identification of dangerous deformation areas in Liupanshui City, Tongren City, Guiyang City and other regions in Guizhou Province. The potential landslide identification methods based on the time series normalized difference vegetation index and landslide development environment elements are combined to investigate hidden landslide hazards in the study area. In this paper, time series InSAR technology is used to monitor three key landslides in Jichang Town, Yujiaying and Fana, to grasp the movement status of the landslide in time. The method of landslide identification and monitoring in this paper is of great significance for disaster prevention and management in Guizhou Province.

scholarly journals PPP-BOTDA Distributed Optical Fiber Sensing Technology and Its Application to the Baishuihe Landslide

2021 ◽  
Vol 9 ◽  
Author(s):  
Meng Zhao ◽  
Xianlong Yi ◽  
Junrong Zhang ◽  
Chengyuan Lin
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Surface Deformation ◽  
Deformation Monitoring ◽  
Landslide Monitoring ◽  
Fiber Sensing ◽  
Sensing Technology ◽  
Optical Fiber Sensing ◽  
Distributed Optical Fiber ◽  
Area Difference

Serious landslide hazards are prevalent along the Yangtze River in China, particularly in the Three Gorges Reservoir area. Thus, landslide monitoring and forecasting technology research is critical if landslide geological hazards are to be prevented and controlled. Pulse-prepump brillouin optical time domain analysis (PPP-BOTDA) distributed optical fiber sensing technology is a recently developed monitoring method with evident advantages in precision and spatial resolution. Herein, fixed-point immobilization and direct burying methods were adopted to arrange parallel distribution of the strain and temperature-compensated optical fibers along the Baishuihe landslide’s front edge, in order to carry out ground surface deformation monitoring. The strain data acquired from both optical fibers were processed with temperature compensation to obtain the actual optical fiber strain produced by deformation. Butterworth low-pass filter denoising method was employed to determine the filter order (n) and cut-off frequency (Wn). The area differences between the two optical fiber monitoring curves and the fixed horizontal axis were selected as evaluation indexes to obtain the area difference along the optical fiber. This data were then leveraged to determine the positive correlation between the area difference and the optical fiber strain variation degree. Finally, these results were compared with the GPS and field measured data. This study shows that when PPP-BOTDA technology is used for landslide surface deformation monitoring in conjunction with Butterworth filter denoising and strain area difference, the optical fiber strain variation degree analysis results are consistent with the GPS monitoring data and the actual landslide deformation. As such, this methodology is highly relevant for reducing the workload and improving the monitoring precision in landslide monitoring, which in turn will protect lives and property.

scholarly journals A Novel Strategy for landslide displacement and its direction monitoring

2013 ◽  
Vol 1 (6) ◽  
pp. 6849-6875
Author(s):  
Z.-W. Zhu ◽  
Q.-Y. Yuan ◽  
D.-Y. Liu ◽  
B. Liu ◽  
J.-C. Liu ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Shear Test ◽  
Base Material ◽  
Time Domain Reflectometry ◽  
Fourth Generation ◽  
Movement Direction ◽  
Landslide Monitoring ◽  
Third Generation ◽  
The Third ◽  
Sliding Distance

Abstract. Landslide monitoring is important in predicting the behavior of landslides, thereby ensuring environmental, life, and property safety. On the basis of our previous studies, we conducted the double shear test by using a third-generation optical fiber transducer that uses expandable polystyrene (EPS) as base material. However, the third-generation transducer has poor performance when cohesive force is present between the grout and capillary stainless steel pipe of the transducer. Thus, the fourth-generation optical fiber transducer was invented. Similar to the third-generation transducer, the fourth-generation transducer also used EPS as its base material. Single shear test was conducted on the fourth-generation transducer after being grouted with cement mortar (1:1 mix ratio). The micro-bend loss mechanism of the optical fiber was considered, and the optical time domain reflectometry instrument was used. The fact that the loss sequence of optical fibers subjected to loading is different at various locations is found. The relationship of the loading-point displacement VS. optical fiber sliding distance and optical loss were measured. Results show that the maximum initial measurement precision of the newly proposed device is 1mm, the corresponding sliding distance is 21 mm, and the dynamic range is 0–20 mm. The fourth-generation transducer can measure the movement direction of loadings, thus making this transducer applicable for landslide monitoring.

scholarly journals Subsidence Monitoring of Fill Area in Yan’an New District Based on Sentinel-1A Time Series Imagery

2021 ◽  
Vol 13 (15) ◽  
pp. 3044
Author(s):  
Mingjie Liao ◽  
Rui Zhang ◽  
Jichao Lv ◽  
Bin Yu ◽  
Jiatai Pang ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Ground Deformation ◽  
Dynamic Change ◽  
Deformation Monitoring ◽  
Chinese Loess Plateau ◽  
Ground Subsidence ◽  
Shanxi Province ◽  
Environment Change ◽  
Loess Area

In recent years, many cities in the Chinese loess plateau (especially in Shanxi province) have encountered ground subsidence problems due to the construction of underground projects and the exploitation of underground resources. With the completion of the world’s largest geotechnical project, called “mountain excavation and city construction,” in a collapsible loess area, the Yan’an city also appeared to have uneven ground subsidence. To obtain the spatial distribution characteristics and the time-series evolution trend of the subsidence, we selected Yan’an New District (YAND) as the specific study area and presented an improved time-series InSAR (TS-InSAR) method for experimental research. Based on 89 Sentinel-1A images collected between December 2017 to December 2020, we conducted comprehensive research and analysis on the spatial and temporal evolution of surface subsidence in YAND. The monitoring results showed that the YAND is relatively stable in general, with deformation rates mainly in the range of −10 to 10 mm/yr. However, three significant subsidence funnels existed in the fill area, with a maximum subsidence rate of 100 mm/yr. From 2017 to 2020, the subsidence funnels enlarged, and their subsidence rates accelerated. Further analysis proved that the main factors induced the severe ground subsidence in the study area, including the compressibility and collapsibility of loess, rapid urban construction, geological environment change, traffic circulation load, and dynamic change of groundwater. The experimental results indicated that the improved TS-InSAR method is adaptive to monitoring uneven subsidence of deep loess area. Moreover, related data and information would provide reference to the large-scale ground deformation monitoring and in similar loess areas.

A landscape-ontology scale MTInSAR deformation monitoring solution for the sustainable conservation of architectural heritage sites

2021 ◽  
Author(s):  
Hang Xu ◽  
FuLong Chen
Keyword(s):  
Large Scale ◽  
Anthropogenic Activities ◽  
Deformation Monitoring ◽  
Global Navigation Satellite Systems ◽  
Structural Defects ◽  
Spatial Density ◽  
Architectural Heritage ◽  
Heritage Sites ◽  
Sustainable Conservation ◽  
Great Wall

<p>Architectural heritage is cultural and spiritual symbol of our predecessors with immeasurable historical, artistic, and technological value. However, these heritages are exposed to long-term degradation due to the combination impacts from the natural erosion and anthropogenic activities. Consequently, it is important to establish an effective deformation monitoring system to support the sustainable conservation of those properties. In order to make complementary to conventional geodetic measurements such as global navigation satellite systems (GNSS) and leveling in terms of spatial density, we propose a landscape-ontology scale multi-temporal InSAR (MTInSAR) solution for the preventive deformation monitoring of large-scale architectural heritage sites through the adaption of current MTInSAR approaches. We apply different solutions in Shanhaiguan section of the Great Wall in China and the Angkor Wat in Cambodia based on their onsite characteristics. At the cultural landscape scale, we improve the small baseline subset (SBAS) approach by the induced pseudo-baseline strategy in order to avoid the errors caused by inaccurate external DEM, resulting in a robust deformation estimation in mountainous areas where the architecture heritage of the Great Wall located; at the ontology scale, we integrate the differential SAR tomography (DTomoSAR) with the finite element method (FEM) for the structural instability detection of the Angkor Wat Temple, pinpointing the structural defects from the 3D deformation measurements and simulation. This study demonstrates the capability of adaptive MTInSAR approaches for the preventive monitoring the deformation of large-scale architectural heritage sites.</p><p><strong>Keywords</strong>: Architectural heritage; two-scale; deformation; MTInSAR</p>

scholarly journals Distributed Fiber Optical Technology for Damage Identification of Engineering Structure

2018 ◽  
Vol 14 (06) ◽  
pp. 17
Author(s):  
Xiaoma Dong ◽  
Liqiang Zhou
Keyword(s):  
Optical Fiber ◽  
Model Test ◽  
Damage Identification ◽  
Dynamic Range ◽  
Optical Loss ◽  
Rock Foundation ◽  
Rock Slide ◽  
Fiber Sensing ◽  
Optical Fiber Sensing ◽  
Interface Slip

<p class="0abstract"><span lang="EN-US">To conduct optical fiber monitoring rock slide model test and optical fiber monitoring of steel concrete interface slip model test, the large triaxial shear test of geotechnical engineering </span><span lang="EN-US">wa</span><span lang="EN-US">s used. First, the data of sliding distance and optical loss and their dynamic range </span><span lang="EN-US">we</span><span lang="EN-US">re obtained. Second, the slide distance and fiber loss relation curve and the fitting equation </span><span lang="EN-US">we</span><span lang="EN-US">re worked out. Finally, the typical applications of optical fiber sensing technology in Rock Engineering (high slope engineering, rock foundation of Dam Engineering) slope stability and geological disaster monitoring </span><span lang="EN-US">we</span><span lang="EN-US">re put forward.</span><span lang="EN-US">The results showed that optical fiber sensing was very sensitive, and the loss value was 30 to 50dB. The dynamic range of rock slide monitoring fiber was 3 to 3.5mm, and the dynamic range of the interface slip monitoring fiber was 1.6mm. Thus, the sensing system can detect the sliding process of the interface between the concrete and the steel plate. It provides some reference for the sliding monitoring of the composite materials.</span></p>

The Optical Fiber Strain Monitoring Technology of Large-Scale Bridge

2012 ◽  
Vol 446-449 ◽  
pp. 3417-3421
Author(s):  
Shu Li Chen ◽  
Mu Biao Su
Keyword(s):  
Optical Fiber ◽  
Large Scale ◽  
Research Result ◽  
Strain Sensor ◽  
Bridge Structure ◽  
Stress Monitoring ◽  
State Monitoring ◽  
Strain Monitoring ◽  
Reliable Performance ◽  
Structure State

Application situation of optical fiber strain sensor used in bridge structure state monitoring is detailed introduced in this paper, two bridges which optical fiber strain sensor is adopted in construction stage stress monitoring and long-time stress monitoring in our country are introduced as example. According to the theoretical analysis of structures, the strain monitoring locations are selected. The composite technology between optical fiber strain sensor and concrete is researched. The installation technology and protect method between optical fiber strain sensor and steel girder are extracted, and advanced acquisition software is explored. Finally, the application foreground of optical fiber strain sensor is discussed. The research result indicates that the optical fiber strain sensor is extraordinary suitable for state monitoring of bridge structure because it has the merits of light structure and reliable performance.

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