Journal articles on the topic 'Deep coal seam'
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1
Wierzchowski, Krzysztof, Jarosław Chećko, and Ireneusz Pyka. "Variability of Mercury Content in Coal Matter From Coal Seams of The Upper Silesia Coal Basin." Archives of Mining Sciences 62, no. 4 (December 20, 2017): 843–56. http://dx.doi.org/10.1515/amsc-2017-0058.
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Abstract The process of identifying and documenting the quality parameters of coal, as well as the conditions of coal deposition in the seam, is multi-stage and extremely expensive. The taking and analyzing of seam samples is the method of assessment of the quality and quantity parameters of coals in deep mines. Depending on the method of sampling, it offers quite precise assessment of the quality parameters of potential commercial coals. The main kind of seam samples under consideration are so-called “documentary seam samples”, which exclude dirt bands and other seam contaminants. Mercury content in coal matter from the currently accessible and exploited coal seams of the Upper Silesian Coal Basin (USCB) was assessed. It was noted that the mercury content in coal seams decreases with the age of the seam and, to a lesser extent, seam deposition depth. Maps of the variation of mercury content in selected lithostratigraphic units (layers) of the Upper Silesian Coal Basin have been created.
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Wang, Feng, Zeqi Jie, Bo Ma, Weihao Zhu, and Tong Chen. "Influence of Upper Seam Extraction on Abutment Pressure Distribution during Lower Seam Extraction in Deep Mining." Advances in Civil Engineering 2021 (October 13, 2021): 1–9. http://dx.doi.org/10.1155/2021/8331293.
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Pressure-relief coal mining provides an effective way to decrease stress concentration in deep mining and ensures mining safety. However, there is currently a lack of research and field verification on the pressure-relief efficiency and influencing factors during upper seam extraction on the lower seam. In order to make up for this deficiency, in this study, field measurements were conducted in panel Y485, which has a maximum depth of 1030 m and is partially under the goaf of the upper 5# seam in the Tangshan coal mine, China, and evolution of advanced abutment pressure was analyzed. Numerical simulations were conducted to study of influence of key strata on advanced abutment pressure. Influence mechanisms of the upper seam extraction on the advanced abutment pressure distribution during lower seam extraction were revealed. The results indicate that the distribution of advanced abutment stress is influenced by the key strata in the overlying strata. The key strata above the upper coal seam were fractured due to the upper coal seam mining, and the advanced abutment stress was only influenced by the key strata between the two seams during lower coal seam mining. When key strata were present between two seams, the extraction of the lower seam still faces potential dynamic disasters after the extraction of the upper seam. In this case, it would be necessary to fracture the key strata between the two seams in advance for the purpose of mining safety. Key strata in the overlying strata of the 5# seam were fractured during extraction, and advanced abutment pressure was only influenced by the key strata located between the two mined seams. The influence distance of advanced abutment pressure in panel Y485 decreased from 73 m to 38 m, and the distance between the peak advanced abutment pressure and the panel decreased from 29 m to 20.5 m, achieving a pronounced pressure-relief effect.
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Zhang, Jianguo, Man Wang, and Yingwei Wang. "Fracture evolution and gas transport laws of coal and rock in one kilometer deep coal mine with complicated conditions." Thermal Science 23, Suppl. 3 (2019): 907–15. http://dx.doi.org/10.2298/tsci180526126z.
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As coal mining gradually extends deeper, coal seams in China generally show high stress, high gas pressure and low permeability, bringing more difficulty to coal mining. Therefore, in order to strengthen gas extraction, it is necessary to carry out reservoir reconstruction after deep coal seams reached. In this paper, the distribution and evolution laws of fracture zone overlaying strata of J15 seam in Pingdingshan No. 10 coal mine after excavation were studied by combining similar simulation and numerical simulation, meanwhile, the gas transport law within fracture zone was numerically simulated. The results show that the fracture zone reaches a maximum of 350 mm in the vertical direction and is 75 mm away from W9,10 coal seams in vertical distance. Since W9,10 coal seams are in an area greatly affected by the bending zone of J15 coal seam under the influence of mining, the mining of J15 coal seam will exert a strong permeability enhancement effect on W9,10 coal seams. The J15 coal seam can act as a long-distance protective layer of W9,10 coal seams to eliminate the outburst danger of the long-distance coal seams in bending zone with coal and gas outburst danger, thereby achiev?ing safe, productive and efficient integrated mining of coal and gas resources. The gas flux of mining-induced fractures in the trapezoidal stage of mining-induced fracture field is far greater than that in the overlaying stratum matrix. The horizontal separation fractures and vertical broken fractures within the mining-induced fracture field act as passages for gas-flow. Compared with gas transport in the overlaying stratum matrix, the horizontal separation fractures and vertical broken fractures within the mining-induced fracture field play a role in guiding gas-flow. The research results can provide theoretical support for the arrangement of high-level gas extraction boreholes in roof fracture zones.
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Han, Feng Shan, and Xin Li Wu. "Numerical Simulation of Compressive Experiment of Coal Seam in Deep Underground for Geological Storage of Carbon Dioxide." Applied Mechanics and Materials 387 (August 2013): 189–92. http://dx.doi.org/10.4028/www.scientific.net/amm.387.189.
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The geological storage of has been recognized as an important strategy to reduce emission in the atmosphere. Coal seam has strong absorption capacity for , hence the coal seam can be used as geological storage reservoirs, simple and easy to use modeling tools would be valuable in assessing the performance of deep underground geological storage. In this paper failure process of coal seam in deep underground under triaxial compressive experiment is presented by numerical simulation. That is of significance and valuable to those subjects of investigation of strength of coal seam in deep underground and mechanism of propagation and coalescence and evolvement of crack for coal seam in deep underground, it is shown by numerical simulation that failure shape of coal seam in deep underground under triaxial compressive experiment of lateral pressure of 25Mpa is typically shear failure, and characteristic of deformation is obviously elastic-brittle, which is significance to understand the performance of the coal seam in deep underground
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Gu, Beifang, Longkang Wang, and Minbo Zhang. "Assessment of Risk Tendency of Coal Bursting Pressure in Deep Outburst Seam." Geofluids 2022 (May 29, 2022): 1–9. http://dx.doi.org/10.1155/2022/9150738.
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In order to analysis the mechanism of coal bursting pressures of deep coal seams and take effective methods to identify, monitor, and control coal bursting pressure, this paper takes 21101 working face of No. 2 coal seam in Dongpang Coal Mine as an example. Risk identification is carried out for the hazardous and harmful factors of coal bursting pressure in coal seam 21101 in Dongpang Coal Mine, and each influencing factor is classified. The hierarchical structure model of the influencing factors of coal bursting pressure in coal seam protruding deep in Dongpang Coal Mine is established in combination with expert opinions, and the weight of each level index is calculated by MATLAB software. The results show that the 21101 working face of No. 2 coal seam in Dongpang Coal Mine has strong impact risk, and the main risk factors include geological structure, impact resistance of coal and rock, mining stress, inducing factors, and emphasis degree of impact risk. According to the results, the corresponding safety measures are put forward to prevent the damage caused by coal bursting pressure in advance and ensure the high quality and safe production in the mine. The qualitative and quantitative methods are used to make the evaluation process more reasonable and scientific. The method could effectively analyze the main factors affecting coal bursting pressure and put forward corresponding safety measures for the main risk factors.
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Hao, Jianchi, Lifeng Ren, Hu Wen, and Duo Zhang. "Experimental Study of Gangue Layer Weakening with Deep-Hole Presplitting Blasting." Shock and Vibration 2021 (November 10, 2021): 1–11. http://dx.doi.org/10.1155/2021/4796500.
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Advances in coal mining technology and an increase in coal output are resulting in increasingly challenging conditions being encountered at coal seams. This is particularly so at thin coal seams, where a large number of hard rock layers known as gangue are often present, which seriously affect the normal operation of the shearer and reduce coal output. Therefore, the effective weakening of hard gangue layers in a coal seam is crucial to ensure that the shearer operates effectively and that coal output is maximized. In this paper, the weakening effect of deep-hole presplitting blasting technology on the hard gangue layer in a coal seam is studied via a similar simulation. Four test schemes are designed: (1) A blasting hole spacing of 200 mm with the holes offset vertically. (2) A blast hole spacing of 300 mm with the holes offset vertically. (3) A blast hole spacing of 200 mm with the holes parallel to the gangue layer. (4) A blasting hole spacing of 200 mm with the holes offset vertically and initiation of interval blasting. The effect of the different blasting hole spacings and arrangements and different detonation methods on the weakening of coal seam clamping by gangue is studied, and the best configuration is identified. This improves the effect of weakening the coal gangue layer by deep-hole presplitting blasting.
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Zheng, Gui Qiang, Biao Can Ling, and Xue Zheng Zhu. "Study on Evaluation System for Coalbed Methane from Deep Coal Seams in China." Advanced Materials Research 962-965 (June 2014): 83–87. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.83.
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In this study, data from 244 CBM production wells were collected and analyzed in China. Based on the data, coalbed methane (CBM) reservoir properties and geological factors were studied. Combined with previous study results, the current situation of CBM resource evaluation, the classification of evaluation indexes and evaluation standard were analyzed. Finally, the evaluation system aiming at deep coal seam CBM was suggested. This system tries to provide important theoretical and technical support to CBM exploration and geological target selection evaluation for deep coal seams in China. This will provide important guideline and technical support to CBM exploration and geological target selection evaluation in deep coal seam CBM in China.
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Shasha, Si, Wang Zhaofeng, Zhang Wenhao, and Dai Juhua. "Study on Adsorption Model of Deep Coking Coal Based on Adsorption Potential Theory." Adsorption Science & Technology 2022 (August 8, 2022): 1–13. http://dx.doi.org/10.1155/2022/9596874.
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With the exhaustion of coal resources in shallow coal seams, many mining areas have moved to deep mining, and the coal storage environment is obviously affected by the mining depth, mainly manifested as the increase of gas pressure and temperature, which makes the adsorption characteristics of deep coal seam gas much more complicated than shallow coal seam. Based on this, this paper chooses Pingdingshan coking coal as the research object, using Hsorb-2600 high-temperature and high-pressure gas adsorption instrument to carry on isothermal adsorption experiment. According to the adsorption theory and the uniqueness of the adsorption characteristics cure, the adsorption model was analyzed and studied. The results show that the predicted curve of coal seam gas adsorption isotherm is in good agreement with the measured curve, the relative error is less than 10%, and the adsorption characteristic curve is logarithmic. At the same time, the model is used to study the variation of adsorbed gas amount with mining depth. The results show that the adsorbed gas amount increases first and then decreases with coal burial depth.
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Zhao, Zhi Gen, Jia Chen, and Jia Ping Yan. "Features of Jianshanchong Klippe and its Control to Gas Geology at Qingshan Coal Mine, Jiangxi Province." Applied Mechanics and Materials 164 (April 2012): 501–5. http://dx.doi.org/10.4028/www.scientific.net/amm.164.501.
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The coal and gas outburst is serious at Qingshan Coal Mine of Jiangxi Province, so it is of significance to research the features of Jianshanchong klippe and its control to gas geology. The research reveals that: Jianshanchong klippe is distributed from the east boundary of Qingshan Coal Mine to No. 45 Exploration Line, its transverse profile is like a funnel while its longitudinal profile is like a wedge, northwest side of the klippe is thicker and deeper while southeast side is thinner and more shallow. Because of the cover and insert of Jianshanchong klippe, the structure of coal-bearing strata is more complex, some secondary folds are formed, and also, the coal seam is changed greatly, the tectonic coal is well developed and the coal seam is suddenly thickening or thinning. Due to the effect of Jianshanchong klippe, the coal and gas outbursts occur in the area of secondary folds, thicker coal seams or tectonic coals. Concerning the prediction of gas geology in deep area, in view of the facts including simpler structure, stable coal seam and decreased thickness, the gas emission rate and the coal and gas outburst will decrease in Fifth and Sixth Mining Level than that in Second and Third Mining Level
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Simatupang, David P., and Deddy Amarullah. "COAL BED METHANE POTENCYOF TANJUNG FORMATION IN TANAH BUMBU SOUTH KALIMANTAN." Buletin Sumber Daya Geologi 5, no. 2 (August 31, 2010): 50–57. http://dx.doi.org/10.47599/bsdg.v5i2.256.
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Coal deposits distributes widely in Indonesia, mainly in Sumatera and Kalimantan. These deposits become an indication for a huge quantity of coal-bed methane (CBM) potency. As an environmentally friendly source of energy, CBM could be one of Indonesia's future energy sources. Centre for Geological Resources (CGR) started the exploration for this energy since 2005, while the study was conducted in 2008 at Tanjung Formation in Tanah Bumbu Area, South Kalimantan.CSAT-1 well was drilled to provide CBM resources and deep coal mine potency data for Tanjung Formation (Eocene) in Asem-asem Basin. This well went through 10 coal seams with three main seam, which is E seam at 212.34-213.30 m depth, I seam at 261.93-264.20 m, and J seam at 270.20-275.35 m depth. Calorific value from this three main seam categorized as high rank coal, vary from 6197-6745 cal/gram (adb), with total moisture between 4.51-7.11 %, adb.Total coal resources used for CBM resources quantification is 112,733,226 tons (between 300 to 1000 meters depth). Based on desorption test and gas chromatograph measurement from samples at various depth from three main seams, those coal gives methane resources estimation about 430 MSCF, with methane content vary between 1.2 - 6.6 cu-ft/ton of coal.
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Guo, Dong Ming, Hua Jun Xue, Li Juan Li, Jun Long Xue, and Gui He Li. "Research on Bursting Liability and its Preventive Measures of -906m Deep Coal and Rock in Zhuji Coal Mine." Applied Mechanics and Materials 170-173 (May 2012): 428–33. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.428.
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Rock burst is a common mine dynamic phenomenon in the world, and the research on bursting liability of coal and rock is the foundation of rock burst’s prevention and treatment. This paper has a research on bursting liability of coal and rock of 11-2 coal seam which is the main coal seam of Zhuji coal mine, and through the research and analysis of coal seam burst energy index(bursting energy index, elastic strain energy index, duration of dynamic fracture) and rock seam burst energy index(bending energy index), this paper given that seam and rock in deep mining section of Zhuji coal mine has bursting liability, put forward a series of countermeasures such as the previous water injection, hole-drilling method, blasting distressing to the coal seam with the impact disaster for deep mining in Zhuji coal mine.
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Wang, Wei, Yanzhao Wei, Minggong Guo, and Yanzhi Li. "Coupling Technology of Deep-Hole Presplitting Blasting and Hydraulic Fracturing Enhance Permeability Technology in Low-Permeability and Gas Outburst Coal Seam: A Case Study in the No. 8 Mine of Pingdingshan, China." Advances in Civil Engineering 2021 (March 22, 2021): 1–12. http://dx.doi.org/10.1155/2021/5569678.
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The current study aims to analyze the principles of integrated technology of explosion to tackle the problems of coal seam high gas content and pressure, developed faults, complex structure, low coal seam permeability, and high outburst risk. Based on this, we found through numerical simulation that as the inclination of the coal seam increases, the risk of coal and gas outburst increases during the tunneling process. Therefore, it is necessary to take measures to reduce the risk of coal and gas outburst. We conducted field engineering experiments. Our results show that the synergistic antireflection technology of hydraulic fracturing and deep-hole presplitting blasting has a significant antireflection effect in low-permeability coal seams. After implementing this technology, the distribution of coal moisture content was relatively uniform and improved the influence range of direction and tendency. Following 52 days of extraction, the average extraction concentration was 2.9 times that of the coal seam gas extraction concentration under the original technology. The average scalar volume of single hole gas extraction was increased by 7.7 times. Through field tests, the purpose of pressure relief and permeability enhancement in low-permeability coal seams was achieved. Moreover, the effect of gas drainage and treatment in low-permeability coal seams was improved, and the applicability, effectiveness, and safety of underground hydraulic fracturing and antireflection technology in low-permeability coal seams were verified. The new technique is promising for preventing and controlling gas hazards in the future.
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Yuan, Anying, Hao Hu, and Qiupeng Yuan. "A Study of the Laws of Abnormal Gas Emissions and the Stability Controls for Coal Mine Walls in Deeply Buried High-Gas Coal Seams." Advances in Civil Engineering 2020 (September 16, 2020): 1–12. http://dx.doi.org/10.1155/2020/8894854.
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At the present time, it is considered to be of major significance to study the gas emission law and stability controls of coal bodies in deeply buried high-gas coal seams. For this reason, in view of the specific problems of gas emissions caused by unstable rib spalling in coal mine walls, comprehensive research methods were adopted in this study, in order to conduct an in-depth examination of micropore structure parameters, gas desorption, diffusion laws, and coal stability levels. The results showed that the development degree of the pores above the micropores, as well as the small pores in soft coal seams, was better than those observed in hard coal seams. In addition, the gas outburst phenomenon was found to have more easily formed in the soft coal seams. The coal body of the No. 6 coal seam in the Xieqiao Coal Mine not only provided the conditions for gas adsorption but also provided dominant channels for gas diffusion and migration. The abnormal gas emissions of the No. 6 coal seam were jointly caused by the relatively developed pores above the small holes in the coal body, rib spalling of coal mine walls, and so on. The research results also revealed the evolution law of mechanical characteristics of the No. 6 coal seam under different water content conditions. It was found that the strength levels of the No. 6 coal seam first increased and then decreased with the increase in water content, and the water content level at the maximum strength of the coal seam was determined to be 7.09%. This study put forward a method which combined the water injection technology of long-term static pressure water injections in deep coal mining holes and real-time dynamic pressure water injections in shallower holes. Field experiments were successfully carried out.
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Zhang, Yong Jiang, Jian Jun Cao, Xian Zheng Meng, and Ben Qing Yuan. "The New Methods of Identify Deep Mine Coal or Rock Dynamic Disasters." Advanced Materials Research 726-731 (August 2013): 936–39. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.936.
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Mine into the deep mining, the power disaster occurs mechanism more complex features fuzzy disasters and hazards common. Outburst and rock burst and other disasters are common differences, the use of traditional coal seam outburst hazard identification method has limitations. According to the kilometers deep test area, the individual indicators law 13-1 coal seam the outburst hazard identification,13-1 coal seam first mining area were identified as non-prominent seam. While outburst identification test area seam burst tendency identification,13-1 coal seam has a strong burst tendentious. The test mine disaster prevention should also consider bumping prevention and control not only consider the gas control. Project research results have important reference conditions similar to mine.
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Li, Shaobo, Lei Wang, Chuanqi Zhu, and Qihan Ren. "Research on Mechanism and Control Technology of Rib Spalling in Soft Coal Seam of Deep Coal Mine." Advances in Materials Science and Engineering 2021 (October 20, 2021): 1–9. http://dx.doi.org/10.1155/2021/2833210.
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In order to solve the difficult problem of coal wall spalling of soft seam in deep mining, the occurrence mechanism of coal wall spalling in deep mining is studied based on the limit equilibrium theory of D-P criterion. Through the analysis of the formula of plastic zone, it can be concluded that the coal wall spalling of soft coal seam is related to mining depth, mining height, stress concentration factor, internal friction angle of coal, cohesion, and the compressive strength of coal body. Also, the change of uniaxial compressive strength of soft coal with different moisture content is studied through laboratory experiments. The experimental results show that the uniaxial compressive strength of soft coal reaches the maximum value when the moisture content is about 3.3%. The comprehensive research shows that the cohesion and strength of coal mass can be improved by increasing the working resistance of support, water injection in advanced deep-hole coal seam of two roadways, and pre-grouting in shallow hole of coal wall. The control measures can effectively control the coal wall spalling of soft coal seam. The research results have important guiding significance for safe and efficient mining of soft coal seam.
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Meng, Qingling, Yanling Wu, Minbo Zhang, Zichao Wang, and Kejiang Lei. "Stability Assessment of Deep Three-Soft Outburst Coal Seam Roof Based on Fuzzy Analytic Hierarchy Process." Shock and Vibration 2021 (May 19, 2021): 1–13. http://dx.doi.org/10.1155/2021/4328550.
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The stability of deep “three-soft” coal seam roof has always been a key issue in coal mining. There are a lot of factors affecting the stability of deep three-soft coal seam outburst roof. However, there is currently no definite method able to draw an accurate assessment conclusion on roof stability. In order to accurately determine the main influencing factors of the stability of deep three-soft coal seam outburst roof and reduce the loss of coal production, this paper performed three-soft coal seam risk identification on Lugou Mine based on the introduction of the fuzzy analytic hierarchy process theory. 23 main risk factors were identified. Then, it established a hierarchical structure model of coal seam roof stability in accordance with experts’ opinions. The analytic hierarchy process was used to calculate the weights of indicators at all levels. Next, the paper used the fuzzy comprehensive evaluation method and expert scoring to evaluate various risk factors in the indicator system, as well as the overall safety level. The results showed that the deep three-soft coal seam stability of Lugou Mine ranks the third hazard level. The main risk and harmful factors include safety awareness, safety monitoring system, roof weakness, ventilation system, fire-fighting system, and rock bolt quality. In response to the evaluation results, this paper formulated corresponding control measure in terms of ventilation risk, safety monitoring risks, construction personnel risks, and fire protection risk to reduce losses in the mining process, providing a new evaluation method for the stability assessment of deep outburst coal seam roof.
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Zhao, Dan, Mingyu Wang, and Xinhao Gao. "Study on the Technology of Enhancing Permeability by Millisecond Blasting in Sanyuan Coal Mine." Mathematical Problems in Engineering 2021 (September 28, 2021): 1–12. http://dx.doi.org/10.1155/2021/8247382.
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To reduce gas disasters in low permeability and high-gas coal seams and improve gas predrainage efficiency, conventional deep-hole presplitting blasting permeability increasing technology was refined and perfected. The numerical calculation model of presplitting blasting was established by using ANSYS/LS-DYNA numerical simulation software. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81–1.0 was the coal rock crushing area, Dlim = 0.19–0.81 was the coal rock crack area, and Dlim = 0–0.19 was the coal rock disturbance area. By comparing and analysing the damage distribution nephogram of coal and rock mass under the influence of different millisecond blasting time interval and the blasting effect of simulation model, the optimal layout parameters of multilayer through cracks were obtained theoretically. And, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The permeability effect was compared and analysed through the analysis of the gas concentration, gas purity, and mixing volume before and after the implementation of deep-hole presplitting blasting antireflection technology, as well as the change of gas pressure, attenuation coefficient, permeability coefficient, and other parameters between blasting coal seams. The positive role of millisecond blasting in reducing pressure and increasing permeability in low permeability and high-gas coal seam were determined.
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Tian, Gan, and Weiyue Hu. "Experimental study on the control effect of ground stress on the damage of coal seam mining floor." E3S Web of Conferences 79 (2019): 02012. http://dx.doi.org/10.1051/e3sconf/20197902012.
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In order to study on mechanism of in-situ stress control on the coal floor damage during deep coal seam mining, the internal relationship among ground stress, mine pressure and floor water inrush was analyzed base on the increasing distribution rule of ground stress with the increasing depth of stratum. It is shown that the stress on the deep coal seam has obvious control effect on the depth of the floor damage and failure through the experimental study and the statistical analysis of the measured data of the mining damage depth of the coal seam floor. And the calculation formula for the depth of the floor failure in the deep seam mining was put forward.
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Cao, Jie, Qianting Hu, Yanan Gao, Minghui Li, and Dongling Sun. "Gas Expansion Energy Model and Numerical Simulation of Outburst Coal Seam under Multifield Coupling." Geofluids 2021 (April 20, 2021): 1–10. http://dx.doi.org/10.1155/2021/5552108.
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Due to the insufficient understanding of the outburst mechanism, the coal and gas outburst disasters in China are more serious. Gas expansion energy is the main source of energy that causes outburst. In order to explore the distribution law of gas expansion energy in outburst coal seams, a gas-solid coupling equation of outburst coal seams was established. The distribution law of coal stress field, deformation field, gas flow field, and gas expansion energy were simulated and analyzed by using COMSOL Multiphysics. The results showed that from the excavation face to the deep part of coal seam, the stress presented unloading zone, stress concentration zone, and original stress zone. The volumetric strain and permeability reached the minimum, while the gas pressure reached the maximum at the peak value of vertical stress. As time goes on, the gas pressure in the fracture near the working face gradually decreased and was less than the pressure in coal matrix. The total gas expansion energy consists of free gas and desorption gas expansion energy. Affected by the excavation, free gas expansion energy maintained a constant value in the original coal seam and gradually decreased in the area close to the working face. The expansion energy provided by desorption gas was zero in the original coal seam. And it first increased and then decreased rapidly near the working face. Compared with stress and coal seam thickness, gas pressure and initial diffusion coefficient had significant influence on gas expansion energy of coal seam. When the diffusion coefficient was greater than 1e-9 m2/s, the gas expansion energy of the coal seam near the working face was significantly higher than that of the original coal seam, which had the risk of inducing outburst.
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Yuan, Benqing, Min Tu, Jianjun Cao, and Xiang Cheng. "Pressure Relief and Permeability Enhancement Mechanism of Short-Distance Floor Roadway in Deep Coal Roadway Strip." Geofluids 2022 (March 24, 2022): 1–12. http://dx.doi.org/10.1155/2022/7430025.
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A pressure relief and permeability enhancement method through short-distance floor roadway was proposed to solve the difficult outburst prevention during the gas extraction at the coal roadway strips in deep outburst coal seams with high ground stress and low gas permeability. On the basis of an equivalent model of the surrounding rock in a deep roadway, the analytical solutions of deep roadway excavation to the stress and deformation of pressure relief at overlying short-distance coal roadway strips were obtained using the unified strength theory and nonassociated flow rules. Next, the criteria for determining the reasonable position of floor roadway were established, and a mechanical model of short-distance floor roadway for the pressure relief and permeability enhancement zone at the overlying coal seam was constructed. Finally, the scope of the zonal disintegration at the coal roadway strips in the elastic and elastic–plastic zones of the surrounding rock in the roadway, as well as the expression of gas permeability change, was given. The engineering trial calculation and practice showed that the stress and strain of the surrounding rock in the roadway were evidently influenced by the intermediate principal stress coefficient. Moreover, the vertical stress and vertical displacement of overlying coal seam were gradually reduced with the increase in the intermediate principal stress coefficient and vertical distance of the floor roadway. The minimum reasonable distance arranged for the 213 floor roadway in Qujiang Coal Mine was 6.21 m, and the effective pressure relief should be conducted within 10.6 m from the coal seam floor. When the pressure relief was located at 9.0 m from the coal seam floor, the investigation results were basically consistent with the theoretical analysis results, exerting obvious pressure relief and permeability enhancement effects on the overlying short-distance coal roadway strips.
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Zhang, Chunlei, Lei Yu, Ruimin Feng, Yong Zhang, and Guojun Zhang. "A Numerical Study of Stress Distribution and Fracture Development above a Protective Coal Seam in Longwall Mining." Processes 6, no. 9 (September 1, 2018): 146. http://dx.doi.org/10.3390/pr6090146.
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Coal and gas outbursts are serious safety concerns in the Chinese coal industry. Mining of the upper or lower protective coal seams has been widely used to minimize this problem. This paper presents new findings from longwall mining-induced fractures, stress distribution changes in roof strata, strata movement and gas flow dynamics after the lower protective coal seam is extracted in a deep underground coal mine in Jincheng, China. Two Flac3D models with varying gob loading characteristics as a function of face advance were analyzed to assess the effect of gob behavior on stress relief in the protected coal seam. The gob behavior in the models is incorporated by applying variable force to the floor and roof behind the longwall face to simulate gob loading characteristics in the field. The influence of mining height on the stress-relief in protected coal seam is also incorporated. The stress relief coefficient and relief angle were introduced as two essential parameters to evaluate the stress relief effect in different regions of protected coal seam. The results showed that the rock mass above the protective coal seam can be divided into five zones in the horizontal direction, i.e. pre-mining zone, compression zone, expansion zone, recovery zone and re-compacted zone. The volume expansion or the dilation zone with high gas concentration is the best location to drill boreholes for gas drainage in both the protected coal seam and the protective coal seam. The research results are helpful to understand the gas flow mechanism around the coal seam and guide industry people to optimize borehole layouts in order to eliminate the coal and gas outburst hazard. The gas drainage programs are provided in the final section.
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Fan, Long, Jiang Cheng Zhong, Bin Han, and Meng Dong. "Sensitivity Analysis of Factors Affecting Asymmetric Deformation of Roadways in Steep Inclined Coal Seam." Advanced Materials Research 717 (July 2013): 255–60. http://dx.doi.org/10.4028/www.scientific.net/amr.717.255.
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There isn`t clear definition of steep inclined coal seam at home or abroad at present. Generally,the inclined coal seam with 35°~55° inclination is called steep inclined coal seam in mining field [. During the mine program in steep inclined coal seam,due to its special formation of roof and floor,not only perpendicular pressure to coal seam is distinct,but also the component of gravity along the direction parallel to coal seam is significantly increased and the parallel pressure which causes slippage of roof and floor is the main factor resulting in the distinct roadway transformation. Uncertainty and asymmetry transformation or destroy of roadways brings great difficulties to the mine of steep inclined coal seam,especially for the asymmetry transformation which is a huge challenge to the support of roadways,so it`s necessary to summary and analyse the factors affecting asymmetry transformation of roadways in steep inclined coal seal. Through classifying these factors by the main and secondary,this paper will provide reference for reasonable arrangement of roadways and effective support scheme in steep inclined coal seam. Many scholars did some research in laws of roadway deformation in steep inclined coal seam,but few of them compared or did sensitivity analyse of these factors. Zhang Bei etc. built the numerical simulation models of roadways with different inclination and found the key position of the deformed surrounding rocks [;Sun Xiaoming etc. aimed at the asymmetric deformation of surrounding rock around deep roadways and investigated its failure mechanism and coupling control countermeasure [;Cao Shugang etc. analysed the stress distribution rules of roadways in steep inclined and medium coal seam by ADINA program and put forward some control measures [. In different inclination conditions, this paper simulates asymmetry deformation of roadways with different section form in steep inclined coal seam through FLAC3D program and analyses the sensitivity of these factors affecting asymmetric deformation.
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Liu, Jian, and Qian Le. "Experimental Study on Deep Borehole Pre-Cracking Blasting of Drilling through Strata at Low Permeability Seam." Advanced Materials Research 868 (December 2013): 339–42. http://dx.doi.org/10.4028/www.scientific.net/amr.868.339.
Full textAbstract:
In the process of roadway excavation in the low permeability outburst coal seam, with drilling through strata in the bottom drainage roadway extracting coal seam gas of control area. In order to improve extraction effect, the method that deep borehole pre-cracking blasting is used to increase the permeability of coal in the drilling through strata seam segment is proposed. The calculation formula on crushing circle and crack circle radius of deep borehole pre-cracking blasting are derived, and the effective loosening radius of blasting is calculated in theory, the research achievements are applied to field test, the test results show that deep borehole pre-cracking blasting permeability improvement technology is carried out in the drilling through strata of the low permeability outburst coal seam, the permeability of coal seam is improved by 180 times, the gas extraction scalar is raised by 8-10 tomes, during the process of roadway excavation, gas concentration of the working face is 0.2%-0.3%, and tunneling footage is increased by 2 times.
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Han, Hao, Shun Liang, Yaowu Liang, Xuehai Fu, Junqiang Kang, Liqiang Yu, and Chuanjin Tang. "The Role of Coal Mechanical Characteristics on Reservoir Permeability Evolution and Its Effects on CO2 Sequestration and Enhanced Coalbed Methane Recovery." Geofluids 2020 (December 3, 2020): 1–28. http://dx.doi.org/10.1155/2020/8842309.
Full textAbstract:
Elastic modulus is an important parameter affecting the permeability change in the process of coalbed methane (CBM)/enhanced coalbed methane (ECBM) production, which will change with the variable gas content. Much research focuses on the constant value of elastic modulus; however, variable stiffness of coal during CO2 injection has been considered in this work. The coupled thermo-hydro-mechanical (THM) model is established and then validated by primary production data, as well as being applied in the prediction of CO2/N2-ECBM recovery. The results show that the harder coal seam is beneficial to primary production, while the softer coal seam results in greater CO2/N2-ECBM recovery and CO2 sequestration. N2 and CO2 mixture injection could be applied to balance early N2 breakthrough and pronounced matrix swelling induced by CO2 adsorption, and to prolong the process of effective CH4 recovery. Besides, reduction in stiffness of coal seam during CO2 injection would moderate the significant permeability loss induced by matrix swelling. With the increase of the weakening degree of coal seam stiffness, CO2 cumulative storage also shows an increasing trend. Neglecting the weakening effect of CO2 adsorption on coal seam stiffness could underestimate the injection capacity of CO2. Injection of hot CO2 could improve the permeability around injection well and then enhance CO2 cumulative storage and CBM recovery. Furthermore, compared with ECBM production, injection temperature is more favorable for CO2 storage, especially within hard coal seams. Care should be considered that significant permeability change is induced by mechanical characteristics alterations in deep burial coal seams in further study, especially for CO2-ECBM projects.
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Jiang, Guo Ping. "The Studies on Gas-Bearing Characteristics of Deep Coal Seams in Yanchang Oil and Gas Province, China." Advanced Materials Research 962-965 (June 2014): 213–16. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.213.
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In this paper, four general directions are described to make evaluations and their resource potential; those are coal structure and coal level, gas content of deep coalbed, the coalbed thickness and distribution and the buried depth of coalbed. Coalfields of the study area are mainly Permian and Carboniferous coal seam of Shanxi Formation coal and Benxi group 11 # coal, coal seam depth 1370-1812m. No. 3 coal-seam average layer thickness of 1.6 m, the monolayer most 2 m thick; No. 11 coal-seam in the average layer thickness of 3 m, single-layer thickness of 4.5 m. Predict the amount of coal resources of 17.3 one hundred million t. Predict coal-bed methane resources of 27.68 billion cubic reserve abundance of 104 million square / km2 in. The exploration results show that this region has good development prospects.
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Di, Jian You, Er Xin Gao, Xian Long Sun, Chang Qing Sun, and Yu Li Chen. "Study on the Relation between the Deep and the Spontaneous Combustion of Coal Seam." Advanced Materials Research 852 (January 2014): 821–25. http://dx.doi.org/10.4028/www.scientific.net/amr.852.821.
Full textAbstract:
Based on the data and laboratory analysis of Sun-Cun Coal Mine, the relationship between the geothermal gradient and the depth of mine in Suncun Coal Mine has been developed. According to this and the laboratory experiments, the relationship between spontaneous combustion period of coal seam and the depth of the mine has been obtained in this article. The results show that the law of coal seam spontaneous combustion period and the mine depth in accordance with the relationship of the gauss curve expression and when the coal mine depth is around 1000 m, the coal seam spontaneous combustion period shortened dramatically. This law should be pay more attention to.
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Xu, Peng, Han-qiao Xiong, Xiao-lin Pu, Ju-quan Liu, and Xing Liu. "Polymer Drilling Fluid with Micron-Grade Cenosphere for Deep Coal Seam." Journal of Chemistry 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/967653.
Full textAbstract:
Traditional shallow coal seam uses clean water, solid-free system, and foam system as drilling fluid, while they are not suitable for deep coal seam drilling due to mismatching density, insufficient bearing capacity, and poor reservoir protection effect. According to the existing problems of drilling fluid, micron-grade cenosphere with high bearing capacity and ultralow true density is selected as density regulator; it, together with polymer “XC + CMC” and some other auxiliary agents, is jointly used to build micron-grade polymer drilling fluid with cenosphere which is suitable for deep coal seam. Basic performance test shows that the drilling fluid has good rheological property, low filtration loss, good density adjustability, shear thinning, and thixotropy; besides, drilling fluid flow is in line with the power law rheological model. Compared with traditional drilling fluid, dispersion stability basically does not change within 26 h; settlement stability evaluated with two methods only shows a small amount of change; permeability recovery rate evaluated with Qinshui Basin deep coal seam core exceeds 80%. Polymer drilling fluid with cenosphere provides a new thought to solve the problem of drilling fluid density and pressure for deep coal seam drilling and also effectively improves the performance of reservoir protection ability.
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Hu, Yanbo, Wenping Li, Qiqing Wang, Xinmin Chen, and Gang Zheng. "Evaluation Method of Water Hazard Control Effect of Coal Seam Floor in Deep Mining: Sequence Verification Evaluation." Geofluids 2022 (October 29, 2022): 1–16. http://dx.doi.org/10.1155/2022/6728045.
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Deep, highly pressurized aquifers seriously threaten the exploitation of resources of North China coalfield. At present, there is no particular guidance system to evaluate the prevention and control effect of water inrush disaster in deep coal seam mining. Therefore, this research focuses on the evaluation of the method for confined water disaster prevention and control effect of deep coal seam mining. Based upon various methods, such as effective thickness and water resistance capacity of aquifuge, water inrush coefficient, GIS (Geographic Information System) analysis of grouting data, dense drilling verification, and professional analysis system based on integrated sequence evaluation, the evaluation of the method for confined water disaster prevention and control effect of deep coal seam mining was put forward for the first time. The proposed method was called the “sequence verification evaluation (SVE)” method. The prevention and control of the effects of Ordovician water inrush disaster in deep mining of Huanghebei coalfield was evaluated using the proposed SVE method. The results show that the SVE method can effectively reflect the prevention and control of the effects of water inrush from confined water and provide scientific basis for the safe production of deep coal seam mining.
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Feng, Cai. "Big Diameter and Long Drilling-Holes Technology and its Application in Drainage Gas in Dingji Coal Mine." Advanced Materials Research 354-355 (October 2011): 104–8. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.104.
Full textAbstract:
Taking advantage of the method of big diameter and long drilling-holes in coal seam’ roof instead of roadway method to drainage gas from coal seam, aimed at the condition of deep coal seam and high risk of outburst in Dingji Coal Mine. The amount and rate of drainage gas was increased, and decreased the time and engineering amount of drainage gas, and effectively diminished the risk of outburst of coal and gas. And a new approach adapt to Dingji Coal Mine to drainage gas is acquired.
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Li, Gang, and Jiafei Teng. "Research and Optimization of Gas Extraction by Crossing-Seam Boreholes from Floor Roadway." Geofluids 2021 (August 9, 2021): 1–10. http://dx.doi.org/10.1155/2021/7499012.
Full textAbstract:
Deep coal seams are characterized by large stress, high gas pressure, and low permeability. The gas disaster threatens the safe production of coal mine seriously. Gas extraction by crossing-seam boreholes from floor roadway (GECMBFR) can reduce the pressure and content of coal seam gas, which is the main measure to prevent gas disaster. Considering the Klinkenberg effect, governing equations of gas adsorption/desorption-diffusion, gas seepage, and stress fields within the coal seam are established to form the seepage-stress coupling model. The governing equations are embodied into a finite element driven software to numerically simulate gas migration and fluid-solid coupling law in coal seam. On this basis, the process of gas extraction under different borehole spacings and diameters is simulated. The effects of these two key parameters on coal seam gas pressure, gas content, and gas permeability were analyzed. The borehole spacing and diameter were determined to be 5 m and 0.09 m, respectively. Combined with the actual situation of a mine, the process of gas extraction from floor roadway with different cross-sectional schemes, ordinary drilling boreholes and punching combined drilling boreholes, is comparatively analyzed. The results show that the gas extraction effect by ordinary drilling boreholes is lower than that of the punching combined drilling boreholes, and the extraction is uneven and makes it difficult to meet the standard. Hydraulic punching was carried out, and coal was washed out of the borehole, which expanded the contact area between the borehole wall and coal seam. The coal seam around the punching borehole is unloaded, which improves coal permeability and accelerates gas migration towards the borehole, thus promoting the efficiency of gas extraction. It is more reasonable to use punching combined drilling borehole scheme when implementing the GECMBFR technology.
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Sun, Yingfeng, Yixin Zhao, Yulin Li, Nima Noraei Danesh, and Zetian Zhang. "Characteristics Evolution of Multiscale Structures in Deep Coal under Liquid Nitrogen Freeze-Thaw Cycles." Geofluids 2021 (October 13, 2021): 1–9. http://dx.doi.org/10.1155/2021/8921533.
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Liquid nitrogen freeze-thaw fracturing has attracted more and more attention in improving the coal reservoir permeability. In order to reveal the impact of liquid nitrogen freeze-thaw on the multiscale structure of deep coal, the multiscale structure evolution law of deep and shallow coal samples from the same seam in the Qinshui coalfield during the liquid nitrogen freeze-thaw cycling was investigated using NMR T 2 spectrum, NMRI, and SEM. The connectivity between mesopores and macropores in deep and shallow coal is improved after liquid nitrogen freeze-thaw cycles. The influence of liquid nitrogen freeze-thaw cycles on the structure evolution of deep and shallow coal is the formation and expansion of microscopic fractures. The initial NMR porosity of deep coal is lower than that of shallow coal from the same coalfield and coal seam. The NMR porosity of both the deep and shallow coal samples increases with the increase of the number of freeze-thaw cycles, and the NMR porosity growth rate of the deep sample is lower than that of the shallow sample.
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Zhang, Lei, Chen Jing, Shugang Li, Ruoyu Bao, and Tianjun Zhang. "Seepage Law of Nearly Flat Coal Seam Based on Three-Dimensional Structure of Borehole and the Deep Soft Rock Roadway Intersection." Energies 15, no. 14 (July 8, 2022): 5012. http://dx.doi.org/10.3390/en15145012.
Full textAbstract:
Exploring the evolution characteristics of gas seepage between boreholes during the drainage process is critical for the borehole’s layout and high-efficiency gas drainage. Based on the dual-porous medium assumption and considering the effect of stress redistribution on coal seam gas seepage characteristics, a coal seam gas seepage model with a three-dimensional roadway and borehole crossing structure has been established and numerically calculated, concluding that the coal seam is between the drainage boreholes. The temporal and spatial evolution characteristics of gas pressure and permeability help elucidate the gas seepage law of the nearly flat coal seam associated with the deep soft rock roadway and borehole intersection model. The results indicate that: (1) The roadway excavation results in localized stress in some areas of the surrounding rock, reducing the strength of the coal body, increasing the expansion stress, and increasing the adsorption of gas by the coal body. (2) Along the direction of the coal seam, the permeability decreases initially and then increases. The gas pressure in the coal seam area in the middle of the borehole is higher than the pressure in the coal seam around the borehole, and the expansion stress and deformation increase, reducing the permeability of the coal body; when near the next borehole, the greater the negative pressure, the faster the desorption of the gas attracts the matrix shrinkage effect and causes the coal seam permeability rate to keep increasing. (3) The improvement of gas drainage with the overlapping arrangement of two boreholes firstly increases and then decreases as time goes on. (4) When the field test results and numerical simulation of the effective area of gas extraction are compared, the effectiveness of the model is verified. Taking the change of the porosity and the permeability into the model, it is able to calculate the radius of gas drainage more accurately.
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Cai, Feng, and Ze Gong Liu. "Research on Similar Materials Simulation Test for Protective Coal-Seams of Group B Coal-Seams of Panyi Coal Mine of China." Applied Mechanics and Materials 204-208 (October 2012): 1389–94. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1389.
Full textAbstract:
Protective technology is one of most effective technologies for regional gas control technology. Huainan Coal Field is a typical coal field with deep and low permeability multi coal-seams, and it is one of most serious coal field in gas disasters. Currently, Huainan Coal Field has completely entered the stage of extracting Group B coal-seams (average mining depth is about 650m). In order to research and obtain the results of stress relief of adjacent coal-seams after extracted protective coal-seam, taking advantage of the method of similar materials simulation test and taking 11415 longwall panel of Group B coal-seams of Panyi Coal Mine of Huainan Coal Field, the changing trends of abutment pressure, displacement as well as permeability of adjacent coal-seams are systematically studied. The researching results can provide safeguard for high-effective gas drainage, eliminate the risk of coal and gas outburst as well as high effective production.
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Wang, Cheng, Zuqiang Xiong, Chun Wang, Yuli Wang, and Yaohui Zhang. "Study on Rib Sloughage Prevention Based on Geological Structure Exploration and Deep Borehole Grouting in Front Abutment Zones." Geofluids 2020 (September 22, 2020): 1–12. http://dx.doi.org/10.1155/2020/7961032.
Full textAbstract:
This research presents the grouting method of preventing rib sloughage which severely impacts mine safety and longwall retreat speed in thick coal seam with numerical simulation and laboratory tests. Based on the analysis of the plastic failure mode of five types of coal seam, roof strata ahead of the longwall face, and fractures developed in the coal seam, the following results are drawn, the range and degree of plastic failure generated in the coal seam and roof strata ahead of the longwall face gradually decreased as the coal mass strength increased; the grouting boreholes are essentially laid out within the coal rib instead of the roof. For a particular case of a coal mine in Shanxi province, a novel cement-based material was grouted, which fulfilled the reinforcement requirements under the tectonic stress regions and front abutment zones. Besides, the grouting borehole construction requested predrilled boreholes, full borehole intubation, lengthened hole sealing, and multiple-step drilling and grouting. This study can provide a theoretical framework of a design overview and practical basis for similar mining conditions in other coalfields.
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Fan, Chaojun, Haiou Wen, Sheng Li, Gang Bai, and Lijun Zhou. "Coal Seam Gas Extraction by Integrated Drillings and Punchings from the Floor Roadway considering Hydraulic-Mechanical Coupling Effect." Geofluids 2022 (January 7, 2022): 1–10. http://dx.doi.org/10.1155/2022/5198227.
Full textAbstract:
Owing to the exhaustion of shallow coal resources, deep mining has been occupied in coal mines. Deep buried coal seams are featured by the great ground stress, high gas pressure, and low permeability, which boost the risk of gas disasters and thus dramatically threaten the security about coal mines. Coal seam gas pressure and gas content can be decreased by gas extraction, which is the primary measure to prevent and control mine gas disasters. The coal mass is simplified into a continuous medium with dual structure of pores and fractures and single permeability. In consideration of the combined effects of gas slippage and two-phase flow, a hydraulic-mechanical coupling model for gas migration in coals is proposed. This model involves the equations of gas sorption and diffusion, gas and water seepage, coal deformation, and evolution of porosity and permeability. Based on these, the procedure of gas extraction through the floor roadway combined with hydraulic punching and ordinary drainage holes was simulated, and the gas extraction results were used to evaluate the outburst danger of roadway excavation and to verify the engineering practice. Results show that gas extraction can reduce coal seam gas pressure and slow down the rate of gas release, and the established hydraulic-mechanical coupling model can accurately reveal the law of gas extraction by drilling and punching boreholes. After adopting the gas extraction technology of drilling and hydraulic punching from the floor roadway, the remaining gas pressure and gas content are reduced to lower than 0.5 MPa and 5.68 m3/t, respectively. The achievements set a theoretical foundation to the application of drilling and punching integrated technology to enhance gas extraction.
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Zhang, Junfei, Fuxing Jiang, Jianbo Yang, Wushuai Bai, and Lei Zhang. "Rockburst mechanism in soft coal seam within deep coal mines." International Journal of Mining Science and Technology 27, no. 3 (May 2017): 551–56. http://dx.doi.org/10.1016/j.ijmst.2017.03.011.
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Cao, Jianjun, Benqing Yuan, Siqian Li, Zunyu Xu, Qihan Ren, and Zhonghua Wang. "Research on Pressure Relief Method of Close Floor Roadway in Coal Seam Based on Deformation and Failure Characteristics of Surrounding Rock in Deep Roadway." Geofluids 2022 (March 30, 2022): 1–16. http://dx.doi.org/10.1155/2022/5820228.
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To solve the high-stress hazard faced in the process of deep mining process, the pressure relief characteristics of gas bearing coal and the deformation characteristics of surrounding rock in deep roadway are studied by means of laboratory test, similar simulation analysis, and field investigation. The investigation results and engineering application showed that the specimens could more easily reach the failure point due to the axial pressure relief under high confining pressure. In addition, the deformation and failure degree of the surrounding rock was higher due to the disturbance from the deep high-stress roadway. The scope of the height affected by the pressure relief of the overlying strata reached above 10 m. Moreover, the initial gas emission could reach 4.41–14.39 times that of the original coal seam by drilling a hole in the coal seam at 10 m from the roof. Thus, the short-distance floor roadway exerted an obvious pressure relief effect on the overlying coal seam.
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Ren, Qihan. "Study on strata behavior law of weak cohesive roof in deep buried fully mechanized top coal caving face." E3S Web of Conferences 267 (2021): 02032. http://dx.doi.org/10.1051/e3sconf/202126702032.
Full textAbstract:
In view of the severe ground pressure behavior and spontaneous combustion risk of goaf in fully mechanized top coal caving face with deep buried weak cohesive roof and thick coal seam prone to spontaneous combustion, combined with theoretical analysis of mining overburden structure and field engineering practice, the structural characteristics of overburden rock and strata pressure behavior law are studied. The results show that: the deep buried thick coal seam fully mechanized top coal caving stope also has the phenomenon of surface step subsidence. Compared with the shallow coal seam, the surface subsidence is relatively slow, and the weak adhesion of the roof leads to the short periodic weighting step distance of the stope, and the average step distance is 9.9m. The measured peak value of advance abutment pressure is 7~10.5m in front of coal wall. According to the mine pressure control and fire prevention demand of goaf, the reasonable advancing speed is 4~5m/d.
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Xiang, Zhe, Nong Zhang, Zhengzheng Xie, Feng Guo, and Chenghao Zhang. "Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study." Applied Sciences 11, no. 9 (April 30, 2021): 4125. http://dx.doi.org/10.3390/app11094125.
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The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.
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Liu, YingJie, Qingjie Qi, and Anhu Wang. "Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams." Shock and Vibration 2021 (January 7, 2021): 1–11. http://dx.doi.org/10.1155/2021/8880041.
Full textAbstract:
The absence of a key stratum during overburden rock movement is crucial to the mining pressure of fully mechanized coal mining faces. Using physical and numerical simulations, the 21304 mechanized mining in Daliuta and Huojitu coal mining faces 1−2 appeared twice during a pressure frame accident analysis. The results indicate that a lack of key overlying strata is crucial to the mining of lower coal seams, particularly for the upper sections of a single key stratum of coal. When the key stratum of the upper coal seam is absent, a stable masonry structure is formed after mining. It is easy to form stable stacked strata at the bottom of a coal seam. When developing gullies in deep terrains, the formation of the key stratum will be an upper rock fracture affected by the impact, resulting in a partial absence of the key stratum. When the key stratum is absent, the mining of upslope working faces and the probability of dynamic strata pressure increase with the overburden on the working face and mining of downslope faces. The face mine pressure development laws on the upper and lower coal seam mining were similar, mainly manifesting as “slope section >valley bottom section >back slope section.”
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Liu, YingJie, Qingjie Qi, and Anhu Wang. "Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams." Shock and Vibration 2021 (January 7, 2021): 1–11. http://dx.doi.org/10.1155/2021/8880041.
Full textAbstract:
The absence of a key stratum during overburden rock movement is crucial to the mining pressure of fully mechanized coal mining faces. Using physical and numerical simulations, the 21304 mechanized mining in Daliuta and Huojitu coal mining faces 1−2 appeared twice during a pressure frame accident analysis. The results indicate that a lack of key overlying strata is crucial to the mining of lower coal seams, particularly for the upper sections of a single key stratum of coal. When the key stratum of the upper coal seam is absent, a stable masonry structure is formed after mining. It is easy to form stable stacked strata at the bottom of a coal seam. When developing gullies in deep terrains, the formation of the key stratum will be an upper rock fracture affected by the impact, resulting in a partial absence of the key stratum. When the key stratum is absent, the mining of upslope working faces and the probability of dynamic strata pressure increase with the overburden on the working face and mining of downslope faces. The face mine pressure development laws on the upper and lower coal seam mining were similar, mainly manifesting as “slope section >valley bottom section >back slope section.”
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Yu, Bin, and Jun Zhao. "Study on Transport Rules and Fully Mechanized Mining with Top Coal Caving Technology of Coal Seam with Huge Thickness in Tashan Mine." Applied Mechanics and Materials 71-78 (July 2011): 3366–69. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.3366.
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For the conditions of coal seam with huge thickness, structural complexity and intrusion by pyrolith in Datong carboniferous period, using laboratory similar simulation, on-site deep basis points observation and working face coal caving measurement, it is found out the migration and release laws of top coal, developed a practical caving technology. It has a good economic efficiency, and it is great significance for similar mining area to mining coal seam with huge thickness.
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Yang, Zhi Hao, Zhi Ping Li, Feng Peng Lai, and Jun Jie Yi. "The Capture, Utilization, Storage of CO2 in Methane Recovery." Advanced Materials Research 1092-1093 (March 2015): 1620–24. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.1620.
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According to the problems that the coalbed methane resource was rich in deep seam in China, but the economic and technology conditions were limited, it would be hard to mine with a conventional method. The CO2 capture, utilization and storage technology was provided (CO2-ECBM). The application of the technology would not only improve the methane recovery ratio from deep and unminable layer, but also put CO2 effectively in the deep layer for storage to reach a target of reducing emission. The study showed that a coal rank, coal seam pressure, coal seam permeability, injection time, injected gas types and others would affect to the recovery ratio of methane in a production mine. Therefore, before we use this technology, a rational evaluation should be conducted on the place location. So the capture and storage technology of CO2 has an important significance in protecting the natural environment.
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Zheng, Guiqiang, Bin Sun, Dawei Lv, Zhejun Pan, and Huiqing Lian. "Study on Reservoir Properties and Critical Depth in Deep Coal Seams in Qinshui Basin, China." Advances in Civil Engineering 2019 (June 2, 2019): 1–7. http://dx.doi.org/10.1155/2019/1683413.
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Coalbed methane (CBM) reservoir properties and relationship of properties with burial depth were studied based on the data derived from 204 deep CBM production wells in Qinshui Basin, China. Through the study, it is found that permeability and porosity decrease with the increase of burial depth and the decreasing trend shows step-change characteristics at a critical burial depth. They also show divisional characteristics at certain burial depth. Gas content, geostress, and geotemperature increase with the increase of burial depth, and the increasing trend shows step-change characteristics and also have divisional characteristics at certain burial depth. Based on the previous study on the reservoir property changes with burial depth, three series of critical depth using different parameters are obtained through simulating the critical depth using the BP neural network method. It is found that the critical depth is different when using different parameters. Combined the previous study with the normalization of three different parameter types, the critical depth in Qinshui Basin was defined as shallow coal seam is lower than 650 m and transition band is 650–1000 m, while deep coal seam is deeper than 1000 m. In deep coal seams, the geological conditions and recovery becomes poor, so it can be defined as unfavorable zones. Therefore, other development means, for example, CO2 injection, need to be used to accelerate the deep coal methane development.
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Salmachi, Alireza, Erik Dunlop, and Mojtaba Rajabi. "Drilling data of deep coal seams of the Cooper Basin: analysis and lessons learned." APPEA Journal 58, no. 1 (2018): 381. http://dx.doi.org/10.1071/aj17055.
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Deep (>4920 ft; >1500 m) coal seams of the Cooper Basin accommodate large amounts of natural gas; however, permeability of this unconventional resource is low and reservoir stimulation in prospective coal intervals is essential to achieve commercial production. This paper aims to analyse drilling data of deep coal seams of the Cooper Basin in South Australia. Drilling data obtained from mud logs are utilised to construct a drillability index (DI), in which rate of penetration is normalised by drilling factors, making DI more sensitive to coal rock strength. Analysis of DI and gas show information provides a preliminary screening tool for studying prospective deep coal seams, before performing in-depth reservoir characterisation and production tests. The decline in DI with depth is attributed to a compaction effect that makes deeper coal seams more difficult to drill through compared with shallow seams. The existence of a fracture network can reduce coal rock strength and consequently DI may increase. The increase in DI may be indirectly related to fluid flow characteristics of the coal seam helping in identifying prospective coal intervals. The DI is also affected by other factors and, hence, should be used in combination with reservoir information to yield conclusive indications. Gas show information and DI results were utilised to indicate the effectiveness of dewatering operation and hydraulic fracture confinement in the wells drilled in the Klebb area located in the Weena Trough.
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Wu, Haojun, Min Gong, Xiaodong Wu, and Yang Guo. "Effect and Response of Coal and Rock Media Conditions on Deep-Hole Pre-Splitting Blasting Techniques for Gas Drainage." Energies 15, no. 22 (November 20, 2022): 8733. http://dx.doi.org/10.3390/en15228733.
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Different types of deep-hole blasting techniques are needed to solve gas drainage problems in complex and variable cases. Blasting parameters suitable for mines are selected based on the relationship between blast stress field changes and gas flow combined with field application and numerical simulation. The Datong Mine was a background to study the blast crush zone and drainage influence range following deep-hole blasting with holes laid in coal seams, which resulted in a 24% increase in gas flow in the drainage hole 6 m from the blast hole. In response to the difficulty of forming blast holes in the soft coal seam of the Yuyang Mine, drilling and blasting in the floor rock stratum adjacent to the coal seam increased the gas flow in the drainage holes by 125%. When applying the deep-hole technique with holes crossing multi-seams for gas drainage in Shiping Mine, the volume of gas drainage increases significantly with increased effective stress in the drainage hole. For example, when the spacing at the hole’s bottom between the blast hole and the drainage hole is 4.6 m, the volume of gas drainage increases by 3.3 times, compared with 8.8 m. Twenty-six protruding mines in southern China have applied the above deep-hole pre-splitting blasting technology, all of which have achieved good results and are of great significance to future applications in multiple fields, such as gas control.
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Chen, Yun, Xinyi Wang, Yanqi Zhao, Haolin Shi, Xiaoman Liu, and Zhigang Niu. "Quantitative Evaluation for the Threat Degree of a Thermal Reservoir to Deep Coal Mining." Geofluids 2020 (November 7, 2020): 1–15. http://dx.doi.org/10.1155/2020/8885633.
Full textAbstract:
Taking the Suiqi coalfield located in North China as the object, where the coal seam burial depth is more than 1100 m, the water abundance of the roof pore thermal storage aquifer is better than average, the ground temperature is abnormally high, and hydrogeological data are relatively lacking, this paper selects and determines eight index factors that influence the mining of the coalfield. Based on the analytic hierarchy process (AHP), the index factor weight is defined, and then, the threat degree of the roof thermal storage aquifer to the coal mining is quantitatively evaluated and divided by using the fuzzy variable set theory. The evaluation results show that the threat degree of the roof in the eastern region is generally greater than that in the western region and that the closer it is to the coal seam outcrop line, the higher the threat degree is; near the boreholes, in the areas Qs1,Qs5, Qs8, Sx1, Tk5, Zc4, and Zc7, which are close to the hidden outcrop line of the coal seam, the classification characteristic value of the threat degree is greater than 3.5, which is in the high-threat zone for disasters caused by roof thermal storage aquifers during coal seam mining. The area above the medium-threat zone accounts for 71.82% of the total study area, indicating that deep coal mining is affected by multiple factors and that roof water and heat disasters are more likely to occur.
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Geng, Mei Hua, Xiu Jiang Lv, and Xiao Gang Zhang. "The Structural Analysis of Deep Gas Occurrence and Prevention of Gas Disaster in Fengfeng Coalfield." Advanced Materials Research 734-737 (August 2013): 484–87. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.484.
Full textAbstract:
The geological structure is an important factor of gas occurrence in coal seam, and the gas occurrence in deep coal seam should be paid attention to enough because the occurrence was more controlled by geological structure and influence. Taken Fengfeng coalfield as target in this paper, the geological structure of this coalfield was described. The deep coal mining district which is monoclinic structure in Fengfeng is located in the east of Gushan anticlinoria, which the junior small anticlines and synclines of the sub-echelon are well developed. And regional fault structures are intensive, the pressure structure is the major structure among this region. The characteristics of geological structure in Fengfeng coalfield were analyzed. The tensional structure planes and pressure structure are the major effect factors, and the latter is the main form of gas occurrence in deep. Some suggestions on safe of deep mining in high gas environment is also put forward, in order to provide theoretical support for the deep coal mining and gas disaster prevention.
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Dou, Litong, Ke Yang, Wenjie Liu, Xiaolou Chi, and Zhijie Wen. "Mining-Induced Stress-Fissure Field Evolution and the Disaster-Causing Mechanism in the High Gas Working Face of the Deep Hard Strata." Geofluids 2020 (September 25, 2020): 1–14. http://dx.doi.org/10.1155/2020/8849666.
Full textAbstract:
The compound dynamic disaster of coal and gas outbursts and rockburst is a typical hazard jeopardizing the mining of the high gas content coal seam under a hard roof condition. In this study, the hard roof’s mechanism inducing this hazard is analyzed. Physical analog modeling experiments and in situ monitoring of mining-induced stress were performed during coal seam mining under a hard roof condition. The pattern of hard roof breakage effect on the stress-fissure field evolution was revealed. The elastic energy was released and propagated on both sides immediately after the hard roof breaking, leading to energy accumulation. Meanwhile, expansive roof collapse resulted in the intense weighting of the working face and rockburst. Thus, the coal and gas outburst occurred under the joint action of the impact energy generated by breaking the hard roof and gas expansion energy. In other words, the compound dynamic disaster happened. Synergistic stereoextraction integrating cross-seam drilling and along-seam drilling was combined with deep hole advanced presplitting blasting technology to cope with the compound dynamic disaster in the high gas coal seam under a hard roof condition.
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He, Fulian, Xiaobin Li, Wenrui He, Yongqiang Zhao, Zhuhe Xu, and Quansheng Li. "The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra-Thick Coal Seams: A Typical Case Study." Advances in Civil Engineering 2020 (August 28, 2020): 1–13. http://dx.doi.org/10.1155/2020/7916729.
Full textAbstract:
Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.