Experimental Study on Deformation Monitoring of Bored Pile Based on BOTDR

Gao, Lei; Han, Chuan; Xu, Zhongquan; Jin, Yingjie; Yan, Jianqiang

doi:10.3390/app9122435

Cited by 25 publications

(11 citation statements)

References 22 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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“…However, further increasing the cushion thickness will lead to a larger settlement. In this simulation, the optimum cushion thickness is about 30 mm [30,31]. Figure 19 presents the influence of cushion thickness on pile-soil stress ratio.…”

Section: Analysis Of Influence Of Cushion Thickness On Bearing Capacitymentioning

confidence: 99%

Study on Bearing Capacity of Tank Foundation with Alternatively Arranged Vortex-Compression Nodular Piles

et al. 2020

Energies

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Types of tapered piles are widely applied in tank foundation consolidation, but their inherent deficiencies in design and construction limit their further promotion. Vortex compression pile is a novel nodular pile. Compared with the traditional equal-section pile, vortex compression nodular pile is featured by stronger bearing capacity and slighter settlement. In this paper, the model test results showed that vortex compression nodular pile can greatly improve the bearing capacity and reduce the settlement. Through the finite element software ABAQUS analysis the bearing characteristics of equal-section pile foundation and vortex-compression nodular pile foundation were compared. The three-dimensional solid model was established by ABAQUS finite element software. The impact of cushion modulus, cushion thickness, vertical load, pile modulus, soil modulus around the pile on the bearing capacity of the vortex-compression nodular pile foundation were studied.

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“…Sensors 2020, 20,1689 15 of 20 measurement model, the measured values of mutual inductance voltage, Hall voltage and tilt measuring voltage of between two adjacent sensing units can be solved as the relative horizontal displacement, vertical displacement and tilt angle in real-time. In the verification experiment, Sensing unit II is moved to be displaced relative to Sensing unit I through the motion controller, the displacement is recorded, and the mutual inductance voltage and Hall voltage at these corresponding points are measured.…”

Section: Experiments and Analysismentioning

confidence: 99%

“…Finally, due to the scalability of the coaxial cable, the measurement range of the TDR technology is limited.BOTDR technology was originally used to measure the surface displacement of geological mass. Now it has been gradually used to measure the underground displacement of rock and soil [17][18][19][20], due to the following features: (1) high stability, good electromagnetism immunity, corrosion resistance, high temperature resistance, etc. ; (2) light weight, small size, suitable for a variety of geometric shapes.…”

mentioning

confidence: 99%

Research on Structure Optimization and Measurement Method of a Large-Range Deep Displacement 3D Measuring Sensor

Shentu

Wang

et al. 2020

Sensors

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Deep displacement monitoring of rock and soil mass is the focus of current geological hazard research. In the previous works, we proposed a geophysical deep displacement characteristic information detection method by implanting magneto-electric sensing arrays in boreholes, and preliminarily designed the sensor prototype and algorithm of deep displacement three-dimensional (3D) measurement. On this basis, we optimized the structure of the sensing unit through 3D printing and other technologies, and improved the shape and material parameters of the permanent magnet after extensive experiments. Through in-depth analysis of the experimental data, based on the data query algorithm and the polynomial least square curve fitting theory, a new mathematical model for 3D measurement of deep displacement has been proposed. By virtue of it, the output values of mutual inductance voltage, Hall voltage and tilt measuring voltage measured by the sensing units can be converted into the variations of relative horizontal displacement, vertical displacement and axial tilt angle between any two adjacent sensing units in real time, and the measuring errors of horizontal and vertical displacement are tested to be 0-1.5 mm. The combination of structural optimization and measurement method upgrading extends the measurement range of the sensing unit from 0-30 mm to 0-50 mm. It shows that our revised deep displacement 3D measuring sensor can better meet the needs of high-precision monitoring at the initial stage of rock and soil deformation and large deformation monitoring at the rapid change and imminent-sliding stage. stage is characterized by cracks in the surface layer of rock and soil mass, followed by collapse [9]. Therefore, studying the deep displacement of rock and soil mass is more in line with the needs of disaster prevention and mitigation than the study of surface displacement. The deep displacement of rock and soil mass can reflect the dynamic stability of rock and soil mass more accurately and quickly, therefore it provides accurate, powerful data and theoretical support for early warning of landslides.However, the deep displacement measuring device must be buried deep underground, requiring the instrument to be strong, anticorrosive, convenient for installation, operation, long-distance signal transmission and so on. At the same time, the deep displacement monitoring environment is harsh and complicated, and there are problems such as no light, water seepage, corrosion, geotechnical shearing and extrusion, which can easily cause damage to the buried instruments. Therefore, compared with surface displacement monitoring, the development of deep displacement monitoring technology is relatively slow, and the types of deep displacement monitoring instruments that can be practically applied are obviously less and have poorer performance. At present, the global monitoring of deep displacement of rock and soil mass mainly includes borehole inclinometer, time domain reflection technology, Brillouin Optical Time Domain Reflection (BO...

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Experimental Study on Deformation Monitoring of Bored Pile Based on BOTDR

Cited by 25 publications

References 22 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

Study on Bearing Capacity of Tank Foundation with Alternatively Arranged Vortex-Compression Nodular Piles

Research on Structure Optimization and Measurement Method of a Large-Range Deep Displacement 3D Measuring Sensor

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