Experimental study on distributed optical fiber sensing monitoring for ground surface deformation in extra-thick coal seam mining under ultra-thick conglomerate

Chai, Jing; Lei, Wulin; Du, Wengang; Yuan, Qiang; Zhu, Lei; Zhang, Dingding; Li, Hao

doi:10.1016/j.yofte.2019.102006

Cited by 23 publications

(13 citation statements)

References 18 publications

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“…Therefore, using DFOS technology to monitor the deformation and failure of rock strata affected by mining becomes a research hotspot nowadays. Many use DFOS in indoor similar model physical simulation experiment of coal mining process to study the movement low of overburden of a simulated working face [32][33][34][35][36]. Although many others using DOFS to monitor the movement of overlying strata or overburden caused by underground coal mining.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

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

Hou

2020

Sensors

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“…A similar test setup was used in Chai et al [ 25 ] in order to establish ground surface movement law for deep and extra-thick coal seam mining under the ultra-thick conglomerate. Similar to the previous article, the authors reported that the PPP-BOTDA DOFS technology could successfully and effectively capture the surface movements and deformations caused by mining.…”

Section: Geotechnical Applicationsmentioning

confidence: 99%

A Review of Recent Distributed Optical Fiber Sensors Applications for Civil Engineering Structural Health Monitoring

Bado

Casas

2021

Sensors

206

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The present work is a comprehensive collection of recently published research articles on Structural Health Monitoring (SHM) campaigns performed by means of Distributed Optical Fiber Sensors (DOFS). The latter are cutting-edge strain, temperature and vibration monitoring tools with a large potential pool, namely their minimal intrusiveness, accuracy, ease of deployment and more. Its most state-of-the-art feature, though, is the ability to perform measurements with very small spatial resolutions (as small as 0.63 mm). This review article intends to introduce, inform and advise the readers on various DOFS deployment methodologies for the assessment of the residual ability of a structure to continue serving its intended purpose. By collecting in a single place these recent efforts, advancements and findings, the authors intend to contribute to the goal of collective growth towards an efficient SHM. The current work is structured in a manner that allows for the single consultation of any specific DOFS application field, i.e., laboratory experimentation, the built environment (bridges, buildings, roads, etc.), geotechnical constructions, tunnels, pipelines and wind turbines. Beforehand, a brief section was constructed around the recent progress on the study of the strain transfer mechanisms occurring in the multi-layered sensing system inherent to any DOFS deployment (different kinds of fiber claddings, coatings and bonding adhesives). Finally, a section is also dedicated to ideas and concepts for those novel DOFS applications which may very well represent the future of SHM.

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“…Tian et al [4] discovered that the abutment pressure of coal pillars doubled, the roof damage intensified, and the scope of overburden structure failure increased under the condition of multiseam mining. Chai et al [5] carried out a research on the internal relationship between overburden structure and surface deformation in the mining process, controlled by the key strata of ultrathick conglomerate which was divided into three stages. Han et al [6] established the key stratum shadow based on a physical simulation test.…”

Section: Introductionmentioning

confidence: 99%

Evolution Law of Coal Seam Abutment Pressure under the Influence of Shallow Buried Complex Strata: A Case Study

Zhang

Sun

Zheng³

2021

Shock and Vibration

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The evolution law of lateral abutment pressure under the condition of fully mechanized mining in shallow coal seam is studied using the change process of coal pillar stress in disturbed section as the research object. The results of physical simulation experiment show that, after coal mining, due to the collapse of coal seam roof, the overlying strata of key layer will disturb the section coal pillar to different degrees, and the sudden change of degrees of abutment pressure near the coal wall reaches the maximum. Affected by the energy released by the fracture of key stratum, the stress mutation area shifts to the coal wall at a deeper level and the range of plastic zone increases. From the perspective of the numerical simulation, according to the change characteristics of coal pillar abutment pressure in the mining process, the dynamic load process of complex roof strata is divided into three stages: the stage not affected by mining, the stage of dynamic load action, and the stage of static load. In the first stage, the lateral abutment pressure is only affected by the roadway mining, causing stress concentration in the coal body. The stress concentration coefficient is small, and the supporting stress is stable. In the second stage, with the advance of the working face, the coal seam load changes continuously owing to the movement of overlying rock in the goaf, and the lateral abutment pressure changes evidently under the influence of dynamic load. In the third stage, the overlying load forms stress concentration in the coal seam and continuously transfers to the coal wall at a deeper level, which increases the limit equilibrium area of coal body. During this period, the range of plastic zone still increases at a certain rate for a period of time and finally tends to be stable.

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Experimental study on distributed optical fiber sensing monitoring for ground surface deformation in extra-thick coal seam mining under ultra-thick conglomerate

Cited by 23 publications

References 18 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

A Review of Recent Distributed Optical Fiber Sensors Applications for Civil Engineering Structural Health Monitoring

Evolution Law of Coal Seam Abutment Pressure under the Influence of Shallow Buried Complex Strata: A Case Study

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