scholarly journals A Novel Approach for Predicting the Height of Water-Conducting Fracture Zone under the High Overburden Caving Strength Based on Optimized Processes

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 950
Author(s):  
Tao Hu ◽  
Gongyu Hou ◽  
Su Bu ◽  
Zhen Zhu ◽  
Yan Wang ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Field Experiment ◽  
Model Simulation ◽  
Coal Mines ◽  
Reference Value ◽  
Time Domain Reflectometry ◽  
Maximum Height ◽  
Protection Measures ◽  
Thick Coal Seam ◽  
Evolution Law

The height of water-conducting fracture zones (WCFZs) is vital for the prevention of water, gas, and roof accidents in coal mines. However, its dynamic evolution law and maximum height are difficult to be obtained by traditional prediction methods, especially for conditions in which there is high overburden caving strength and a thick coal seam. Therefore, taking the 150,313 fully mechanized caving working face in Yingying Coal Mine as a background, according to the principle of optimized processes, a new predicting approach based on the Brillouin optical time-domain reflectometry (BOTDR) is proposed. Firstly, we estimated the height through empirical formula calculation, theoretical analysis, and similar model simulation tests. Secondly, we studied the optimized layout of optical cables in the overburden in detail for predicting the maximum height of the WCFZ and keeping the cables in good performance during field prediction. Thirdly, we researched and optimized the borehole parameters, optical fiber selection, and the special protection measures. Finally, we applied the aforementioned optimized outcomes in the field experiment to dynamically predict the height of the WCFZ. As a result of the field experiment, the distribution characteristics of optical fiber strain, the maximum height, and the evolution law of the WCFZ were obtained through the regular monitoring of fiber strain using BOTDR. The experiment demonstrated that its maximum height is consistent with the results studied indoors. The validation and feasibility of the approach proposed in this paper were verified via the aforementioned studies. The research in this paper has good reference value and important significance for predicting the height of the WCFZ using BOTDR in coal mines with similar geological and productive conditions.

Application of optical fiber oxygen sensor in coal mines

2014 ◽  
pp. 1109-1111 ◽  
Author(s):  
Yanjie Zhao ◽  
Yubin Wei ◽  
Yanfang Li ◽  
Tingting Zhang ◽  
Weisong Zhao ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Oxygen Sensor ◽  
Coal Mines

Measurement of Optical Fiber Temperature Sensing Based on Coherent Optical Time Domain Reflectometry

2010 ◽  
Vol 39 (11) ◽  
pp. 1988-1992
Author(s):  
李荣伟 LI Rongwei ◽  
李永倩 LI Yongqian ◽  
杨志 YANG Zhi ◽  
李保罡 LI Baogang
Keyword(s):  
Optical Fiber ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Temperature Sensing ◽  
Optical Time Domain Reflectometry ◽  
Optical Time

scholarly journals Study on Reasonable Size of Coal and Rock Pillar in Dynamic Pressure Roadway Segment of Fully Mechanized Face in Deep Shaft

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Binyang Sun ◽  
Pingsong Zhang ◽  
Haifeng Lu
Keyword(s):  
Optical Fiber ◽  
Dynamic Pressure ◽  
Time Domain Reflectometry ◽  
Geological Condition ◽  
Good Correspondence ◽  
Stress Variation ◽  
Rock Pillar ◽  
Working Face ◽  
Strata Deformation ◽  
Rock Strata

The deformation mechanism of the protective coal and rock pillar area outside a stope is an important parameter for setting a reasonable size. In this paper, based on the geological condition of working face 1231(1) in a mine in Huainan, a method that combines the use of a borehole and Brillouin optical time domain reflectometry (BOTDR) was proposed to analyze the stress variation laws of coal and rock pillar areas, and the parameters of the monitoring borehole and installation technique of the sensing optical cables were designed. Based on the monitoring data, the strain distribution characteristics of the sensing optical cables and their relationship with the rock strata were analyzed, the development law of coal and rock strata deformation during the mining process was revealed, and the transverse influence range of the coal and rock pillar affected by mining was reasonably divided. According to the results, the sensing optical cables show an overall trend of tensile strain, with a maximum value of 1800 με, and the main areas of rock strata deformation occur near the interface of rock strata. The range of rock strata disturbance along the borehole direction was approximately 38 m, and the maximum deformation of rock strata after the disturbance, namely, the displacement, was 24.87 mm. A numerical model was constructed to acquire the strain variation characteristic within 100 m in the outer floor of the working face. The transverse range of the floor disturbance was analyzed to be 30–36 m. The field test had good correspondence with the numerical simulation results, which indicates that the optical fiber testing technology can effectively describe the stress variation in the coal and rock strata. The test results can provide technical support for the rational setting of coal and rock pillars and disaster prevention and control. The research direction of deep rock mass testing is discussed, and optical fiber testing in boreholes is considered an effective method for studying deep dynamic disaster control.

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

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 80 ◽  
Author(s):  
Ricardo Moffat ◽  
Pablo Parra ◽  
Miguel Carrasco
Keyword(s):  
Optical Fiber ◽  
Earth Pressure ◽  
Time Domain Reflectometry ◽  
Body Motion ◽  
Soil Pressure ◽  
Optical Time Domain Reflectometry ◽  
Excavation Process ◽  
Topographic Survey ◽  
Optical Time ◽  
Horizontal Displacements

Horizontal displacements of a multiple-anchor pile wall in a 28.5 m deep excavation using the top–down construction method have been monitored using optical fiber (Brillouin optical time-domain reflectometry (BOTDR)), strain gauges, inclinometers, and a topographic survey. This work presents a comparison between these different techniques to measure horizontal displacements in the pile at several stages of the soil excavation process. It was observed that displacements can be separated into two components: Rigid body motion and pile flexural deformation. Measurements using optical fiber and inclinometers are considered the most adequate and easy to install. A numerical model allows us to evaluate the influence of earth pressure on the estimated horizontal displacements. It is shown that using soil pressure on the wall given by p = 0.65Kaγh, on a simplified modeled wall, provides a close deduction of horizontal displacements compared to observed values on the field.

scholarly journals Keeping Watch on Intangible Cultural Heritage: Live Transmission and Sustainable Development of Chinese Lacquer Art

2019 ◽  
Vol 11 (14) ◽  
pp. 3868 ◽  
Author(s):  
Xiaoting Song ◽  
Yongzhong Yang ◽  
Ruo Yang ◽  
Mohsin Shafi
Keyword(s):  
Sustainable Development ◽  
Cultural Heritage ◽  
Reference Value ◽  
Final Conclusion ◽  
Chinese Government ◽  
Intangible Cultural Heritage ◽  
Protection Measures ◽  
Whole Process ◽  
Countermeasures And Suggestions ◽  
Depth Interviews

Countries all over the world have been constantly exploring ways to rescue and protect intangible cultural heritage. While learning from other countries’ protection measures, the Chinese government is also constantly exploring ways that conform to China’s national conditions. As China’s first batch of intangible cultural heritage, lacquer art boasts a brilliant history, but many people are not familiar with it today. Moreover, in the process of modernization, the lacquer art transmission is declining day by day, and it is facing unprecedented major crises such as loss and division of history into periods. Hence, it is essential to verify and reveal the challenges and dilemmas in the lacquer art transmission, and come up with corresponding protection measures around these problems. First of all, this research, through literature review, “horizontally” explores the current research status and the universal problems of lacquer art transmission from the macro level. With a view to make up for the deficiencies of the existing research and further supplement the empirical evidence, the current research, with the transmission of “Chengdu lacquer art” as an example and through in-depth interviews, tracks and investigates the whole process of transmission of Chengdu Lacquer Art Training Institute, and “vertically” analyzes the survival situation of lacquer art transmission and the core problems affecting transmission behaviors from the micro level. In the final conclusion, the research comes up with corresponding countermeasures and suggestions for the identified key problems, which is of significant reference value for facilitating the live transmission and sustainable development of Chinese lacquer art.

scholarly journals Comparative Experimental Study of a High-Temperature Raman-Based Distributed Optical Fiber Sensor with Different Special Fibers

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 574 ◽  
Author(s):  
Ismail Laarossi ◽  
María Quintela-Incera ◽  
José López-Higuera
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Optical Fiber Sensor ◽  
Time Domain Reflectometry ◽  
Fiber Sensor ◽  
Mechanical Resistance ◽  
Distributed Optical Fiber Sensor ◽  
Distributed Optical Fiber

An experimental study of a high temperature distributed optical fiber sensor based on Raman Optical-Time-Domain-Reflectometry (ROTDR) (up to 450 °C) and optical fibers with different coatings (polyimide/carbon, copper, aluminum and gold) is presented. Analysis of the distributed temperature sensor (DTS) measurements determined the most appropriate optical fiber to be used in high temperature industrial environment over long periods of time. To demonstrate the feasibility of this DTS for an industrial application, an optical cable was designed with the appropriate optical fiber and it was hermetically sealed to provide the required mechanical resistance and isolate the fiber from environmental degradations. This cable was used to measure temperature up to 360 °C of an industrial furnace during 7 days.

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