Monitoring a 28.5 m High Anchored Pile Wall in Gravel Using Various Methods

Moffat, Ricardo; Parra, Pablo F.; Carrasco, Miguel

doi:10.3390/s20010080

Cited by 7 publications

(5 citation statements)

References 17 publications

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“…The main stream DFOS widely used in strain monitoring based on Brillouin Scattering technology are the BOTDR, BOTDA, and BOFDA [43]. They have been applied to the strain monitoring of various kinds of structures in many industries, such as high anchored pile wall in gravel [44], Bored Pile [45], Pile Foundation [46], Beam Bridges [47], similar material test model [48], steel rails [49], subsea Sensors 2020, 20, 1318 4 of 31 cables [50], geotechnical structures [51], River Levee Collapse, Concrete Structures and yacht [52], tunnel healthy [53], the state of underground copper mine [54], land subsidence [55], airplane structure health [56], and so on.…”

Section: Distributed Fiber Optical Sensor (Dfos) Technologymentioning

confidence: 99%

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

Hou

2020

Sensors

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Mining deformation of roof strata is the main cause of methane explosion, water inrush, and roof collapse accidents amid underground coal mining. To ensure the safety of coal mining, the distributed optical fiber sensor (DFOS) technology has been applied in the 150,313 working face by Yinying Coal Mine in Shanxi Province, north China to monitor the roof strata movement, so as to grasp the movement law of roof strata and make it serve for production. The optical fibers are laid out in the holes drilled through the overlying strata on the roadway roof and BOTDR technique is utilized to carry out the on-site monitoring. Prior to the on-site test, the coupling test of the fiber strain in the concrete anchorage, the calibration test of the fiber strain coefficient of the 5-mm steel strand (SS) fiber, and the test of the strain transfer performance of the SS fiber were carried out in the laboratory. The approaches for fiber laying-out in the holes and fiber's spatial positioning underground the coal mine have been optimized in the field. The indoor test results show that the high-strength SS optical fiber has a high strain transfer performance, which can be coupled with the concrete anchor with uniform deformation. This demonstrated the feasibility of SS fiber for monitoring strata movement theoretically and experimentally; and the law of roof strata fracturing and collapse is obtained from the field test results. This paper is a trial to study the whole process of dynamic movement of the deformation of roof strata. Eventually the study results will help Yinying Coal Mine to optimize mining design, prevent coal mine accidents, and provide detailed test basis for DFOS monitoring technique of roof strata movement.both ends along the long axis direction; when the two cracks increase to a certain length, cracks appear in the middle of the short axis and propagate to both ends; second, the cracks continue to expand in the long axis and the short axis directions, and are penetrated by the arc curve at four corners to form an "O-shaped" closed crack curve; finally, the "X-shaped" cracks are full of the "O-shaped" closed curve. At this time, the four sides of the fixed support plate will break into four geometrically movable rock blocks, the four rock blocks will rotate sink to the goaf like a cantilever beam. With the collapse of the broken roof strata, the broken rock blocks accumulate to be a loose rock body, the loose body then support the sinking roof strata, finally the Voussoir Beam Structure forms, which the Key Block is simplified into an arch with three articulations [1][2][3]. At present, Voussoir Beam hypothesis is widely used in China to design and guide coal mining. According to the hypothesis, the overlying strata movement of stope is divided into three zones in horizontal and vertical direction, as shown in Figure 1. The overburden of stope is divided into caving zone, fracture zone, and bending subsidence zone from bottom to top. In the advancing direction of the working face, Block A represents the Key Block ...

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Section: Distributed Fiber Optical Sensor (Dfos) Technologymentioning

confidence: 99%

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

Hou

2020

Sensors

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“…Figure 10 shows the calculation differences between the ICTool and the DigiPro2 software (ICT-DP2) which has a maximum value of less than 0.005 mm while the maximum value (SM-DP2) between SiteMaster 2012 and DigiPro2 is about 0.10 mm. These deviations are very tiny in comparison with bias and measuring errors (Grodecki et al, 2018;Moffat et al, 2019) or technical requirements (Liu et al, 2011;Pei et al, 2021) of basement diaphragm wall monitoring so they can be omitted.…”

Section: Resultsmentioning

confidence: 99%

“…For example, when processing GK-604D data using Geoslope's DigiPro2 software, without any notes from the manufacturers, an instrument constant of 40000 was selected to obtain the correct displacement value according to the calculation principle of Geokon manufacturer. These confusions in the inclinometer data processing have put the Vietnamese surveyors in an embarrassing situation and there is even a possibility that readings are interpreted incorrectly resulting in misleading wall deflections (Moffat et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Solution of inclinometer data processing for horizontal displacement: A case study of basement diaphragm wall monitoring in Vietnam

Trong,

Dung,

Quang

2023

Reports on Geodesy and Geoinformatics

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In the recent decade, Digitilt DataMate II and GK-604D inclinometer systems have commonly been used to evaluate horizontal displacement as well as to test the calculation models of basement diaphragm walls in Vietnam. The difference in the equipment constants as well as the calculation principle has confused the surveyors and even led to erroneous monitoring results. Furthermore, the use of commercial programs DigiPro2 and SiteMater, which are expensive, in inclinometer data processing requires a thorough understanding. Differences in calculation results between software occur due to the choice of the instrument constant, the rounding principle, or the choice of the reference point at the bottom of the monitoring pipe. In this paper, we summarize the calculation principles of Digitilt DataMate II and GK-604D inclinometer systems. To respond well to the data processing of inclinometer systems for basement diaphragm walls in Vietnam, we have developed the ICTool program that can efficiently calculate the observed data of the GK-604D system. The results of inclinometer data processing by the ICTool program are homogeneous in comparison with DigiPro2 and SiteMater software. In addition, the ICTool program was established to provide, free of charge, the communication of the monitoring of basement diaphragm wall displacement in Vietnam.

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Section: Introductionmentioning

confidence: 99%

“…In this case, a reinforced 5 mm optical fiber cable fixed along steel bars was used. Moffat et al [14] showed a comparison between BOTDR, strain gauges, inclinometers, and topographic survey methods to monitor a multiple-anchor pile wall in 28.5 m deep excavation. Nowadays, steel-based sheet piles are very often replaced by hybrid composite materials like a polyvinyl chloride matrix locally reinforced with glass fibers [15].…”

Section: Introductionmentioning

confidence: 99%

Optical Fiber Sensor for PVC Sheet Piles Monitoring

2021

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This paper examined the impact of optical fiber sensor design, and its integration to PVC (polyvinyl chloride) sheet piles, on deflection and strain monitoring. Optical fiber sensors based on Brillouin light backscattering (BLS) were prepared, as they can provide accurate strain and deflection measurement results. However, depending on the application of sheet piles systems, high deformation of PVC elements can be observed. Therefore, a fiber sensor design is not trivial. Three types of optical fiber coatings and their integration with PVC sheet piles were investigated. The effect on the value of compressive and tensile strain were analyzed. It has been experimentally proven that PVC sheet piles monitoring, based on BLS method, can be realized using optical fibers with 250 µm, 900 µm, and 3 mm coating diameter. Achieved results are in line with theory. Correction coefficient necessary for 900 µm and 3 mm coatings has been proposed and used to ensure proper strain measurement. It was found that 250 µm coating fiber based sensors can be utilized for PVC strain measurement under low deflection (>1.2 m beam length). On the other hand, sensors based on 3 mm coating fiber, due to a high level of linearity, can be applied to deflection distance measurement under high deformation.

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Monitoring a 28.5 m High Anchored Pile Wall in Gravel Using Various Methods

Cited by 7 publications

References 17 publications

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

Solution of inclinometer data processing for horizontal displacement: A case study of basement diaphragm wall monitoring in Vietnam

Optical Fiber Sensor for PVC Sheet Piles Monitoring

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