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Gas drainage is an important method to prevent and control gas disasters. Sealing materials have an important impact on the gas drainage effect. To improve the extraction rate, the configuration and related characteristics of sealing materials were studied in this study. It was found that the fluidity increased gradually with the increase of the dosage of the suspension concentrate (SC). The water–cement ratio was directly proportional to the setting time of the slurry. Also, the mixing amount of the special cement was inversely proportional to the setting time of the slurry. The influence of the amount of foaming agent, special cement, and suspending agent on the expansion rate of the slurry was positive, and the influence gradually weakened. When the water–cement ratio of cement-based materials was 0.6, the special cement content percentage was 6, the suspension agent content percentage was 3, the plasticizer content percentage was 0.7, the early strength agent content percentage was 1.2, and the foaming agent content percentage was 0.2, the sealing effect was the best. The research results suggest that the porosity and pore length of the cement-based material are smaller than those of polyurethane, and its sealing property was better. This could further increase the sealing effect of the gas borehole, thereby facilitating gas extraction.
Jianhua Fu; Dengke Wang; Xuelong Li; Zhiming Wang; ZhengJie Shang; Zhigang Jiang; Xiaobing Wang; Xin Gao. Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing. ACS Omega 2021, 6, 21094 -21103.
AMA StyleJianhua Fu, Dengke Wang, Xuelong Li, Zhiming Wang, ZhengJie Shang, Zhigang Jiang, Xiaobing Wang, Xin Gao. Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing. ACS Omega. 2021; 6 (32):21094-21103.
Chicago/Turabian StyleJianhua Fu; Dengke Wang; Xuelong Li; Zhiming Wang; ZhengJie Shang; Zhigang Jiang; Xiaobing Wang; Xin Gao. 2021. "Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing." ACS Omega 6, no. 32: 21094-21103.
Aiming at the problem that the coal seam temperature is high and the gas desorption rate is fast, the gas content loss is estimated to be biased, resulting in inaccurate measurement of coal seam gas content. This paper proposes a method for taking the coal samples at low temperature (below 0 °C) in order to improve the accuracy of gas content measurement by suppressing the release of gas. Based on the importance of gas adsorption desorption in the prediction of gas diffusion law in coal, this paper analyzes the gas adsorption/desorption characteristics of standard size raw coal in low-temperature environment with self-designed low-temperature environment gas adsorption/desorption test platform. Experimental study has been conducted on the gas adsorption promotion and desorption restrain of environmental coal. The results show that (1) the temperature increase promotes the adsorption of coal to gas. The lower the temperature is, the more obvious the adsorption effect will be; and the lower the temperature inhibits the gas desorption; likewise the lower the temperature is, the more obvious the restrain of desorption will be. (2) The gas desorption rate of coal can be divided into three significant stages. Among them, stage I has the shortest time, the desorption rate is the largest, and the gas desorption amount is the most; stage III is the longest, the gas desorption rate is the second, and the gas desorption amount is the middle; stage II desorption rate is the smallest, and the desorption amount is the least. (3) Lowering the temperature has different effects on the gas desorption rate of coal in three stages. The gas desorption rate of the coal in the first stage is mainly suppressed, and the gas desorption rate data has a quadratic function increasing with the increase of the adsorption equilibrium temperature. However, the gas desorption in the second and third stages of coal is a promoting effect, and the gas desorption rate data decreases with the increase of the adsorption equilibrium temperature. (4) The research on the gas desorption restrain effect of low temperature environment coal will provide theoretical basis for the development and application of underground cryo-coring technology.
Fakai Wang; Xuelong Li; Bo Cui; Jian Hao; Xin Gao; Kun Long; Peng Chen; Sheng Wang. Experimental study on adsorption promotion and desorption restrain of gas-containing coal in low-temperature environment. Arabian Journal of Geosciences 2021, 14, 1 -12.
AMA StyleFakai Wang, Xuelong Li, Bo Cui, Jian Hao, Xin Gao, Kun Long, Peng Chen, Sheng Wang. Experimental study on adsorption promotion and desorption restrain of gas-containing coal in low-temperature environment. Arabian Journal of Geosciences. 2021; 14 (12):1-12.
Chicago/Turabian StyleFakai Wang; Xuelong Li; Bo Cui; Jian Hao; Xin Gao; Kun Long; Peng Chen; Sheng Wang. 2021. "Experimental study on adsorption promotion and desorption restrain of gas-containing coal in low-temperature environment." Arabian Journal of Geosciences 14, no. 12: 1-12.
The variation of the in situ stress state is closely related to various factors. In situ stress state is also an important indicator to guide mining production. The study of in situ stress measurement and its distribution characteristics has always been a basic and very important work in mine production. In this study, the deep mines of Linyi Mining Area were considered as the research object. In this regard, the stress distribution law of each mine was studied. We found that the relationship between principal stresses was σH > σ v > σh, which belongs to the strike-slip stress regime. In this stress regime, the lateral Earth pressure coefficient was greater than one, and the magnitude of the three principal stresses all showed an increasing trend with the increase of depth. The maximum horizontal stress direction of the Gucheng Coal Mine, Guotun Coal Mine, and Pengzhuang Coal Mine was NW-SE under the influence of regional geological structure, while the maximum horizontal stress direction of Wanglou Coal Mine was NE-SW under the influence of local geological structure. Besides, the relationship between mine in situ stress and mine geological structure, the impact of original rock stress on stope stability, and the effect of original rock stress on floor water inrushing were also investigated. We believe that the research results are beneficial to mine disaster prevention and safety production.
Xuelong Li; Shaojie Chen; Sheng Wang; Meng Zhao; Hui Liu. Study on In Situ Stress Distribution Law of the Deep Mine: Taking Linyi Mining Area as an Example. Advances in Materials Science and Engineering 2021, 2021, 1 -11.
AMA StyleXuelong Li, Shaojie Chen, Sheng Wang, Meng Zhao, Hui Liu. Study on In Situ Stress Distribution Law of the Deep Mine: Taking Linyi Mining Area as an Example. Advances in Materials Science and Engineering. 2021; 2021 ():1-11.
Chicago/Turabian StyleXuelong Li; Shaojie Chen; Sheng Wang; Meng Zhao; Hui Liu. 2021. "Study on In Situ Stress Distribution Law of the Deep Mine: Taking Linyi Mining Area as an Example." Advances in Materials Science and Engineering 2021, no. : 1-11.
Using the self-developed three-axis servo fluid-solid coupling system with gas-solid coupling of gas-bearing coal, the variation law of the permeability of gas coal under the stress cycle loading and unloading path was studied. The qualitative and quantitative relationships between permeability, axial force, and radial stress of gas-bearing coals were established, and the variation law of permeability of gas-bearing coals was discussed. The results show that (1) different cyclic loading and unloading stress paths correspond to the permeability characteristics of different gas-bearing coals. (2) Permeability of gas-bearing coal decreases with the increase of axial stress and radial stress, and it has a logarithmic function with axial stress and radial stress. This shows that axial stress and radial stress are important factors affecting the permeability characteristics of gas-bearing coal. (3) Under the same stress loading and unloading conditions, the axial stress is less than radial stress on the permeability of gas-bearing coal. In the cyclic loading and unloading axial stress process, the permeability of the gas-bearing coal varies by a smaller extent than the cyclically unloaded confining force. (4) The cumulative damage rate of gas-bearing coal under axial stress gradually increases with the increase of the number of cycles of loading and unloading, and the rate of the cumulative damage rate of permeability is less than the corresponding rate of radial stress.
Fakai Wang; Xuelong Li; Bo Cui; Jian Hao; Peng Chen. Study on the Permeability Change Characteristic of Gas-Bearing Coal under Cyclic Loading and Unloading Path. Geofluids 2021, 2021, 1 -12.
AMA StyleFakai Wang, Xuelong Li, Bo Cui, Jian Hao, Peng Chen. Study on the Permeability Change Characteristic of Gas-Bearing Coal under Cyclic Loading and Unloading Path. Geofluids. 2021; 2021 ():1-12.
Chicago/Turabian StyleFakai Wang; Xuelong Li; Bo Cui; Jian Hao; Peng Chen. 2021. "Study on the Permeability Change Characteristic of Gas-Bearing Coal under Cyclic Loading and Unloading Path." Geofluids 2021, no. : 1-12.
The rapid construction of a shaft is very important for shortening the shaft construction period and improving the mine economic benefits. In addition to the effects of hydrogeological conditions, the shaft construction speed also affects the selection of operation mode and the rationality of mechanical equipment. Considering the specific geological conditions of thick alluvium and large aquifers on the surface of auxiliary shaft in Fucheng mine, the main factors which affect the construction speed of the large-section vertical shaft in the thick alluvium are analyzed in this study. Based on the field investigations and hydrogeological conditions of the auxiliary shaft, the freezing method is determined as a rapid construction scheme for the auxiliary shaft as well as designing the arrangement of freezing holes and optimization of freezing parameters. The dynamic adjustment of freezing parameters is identified by studying the information provided by freezing construction technology. After shaft excavation, the deformation of the shaft lining in the alluvium section of topsoil is analyzed. It is concluded that the deformation of the shaft lining increases with the depth of the topsoil layer, however, the maximum deformation is within the allowable range of design. The short section excavation and masonry mixed operation mode is selected, and “five major and one deep” rapid mechanized operation lines are matched. The scientific operation cycle chart is compiled. And operation results fulfilled the actual needs. These results will provide guidance and reference significance for mine construction under similar geological conditions.
Jiankun Xu; Xuelong Li; Xinzeng Xu; Zan Li; Baolin Li; Danyang Xi; Shumin Liu. Study on the rapid construction method of large section vertical well in thick alluvium. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 2020, 1 -14.
AMA StyleJiankun Xu, Xuelong Li, Xinzeng Xu, Zan Li, Baolin Li, Danyang Xi, Shumin Liu. Study on the rapid construction method of large section vertical well in thick alluvium. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. 2020; ():1-14.
Chicago/Turabian StyleJiankun Xu; Xuelong Li; Xinzeng Xu; Zan Li; Baolin Li; Danyang Xi; Shumin Liu. 2020. "Study on the rapid construction method of large section vertical well in thick alluvium." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects , no. : 1-14.
Liquid nitrogen fracturing technology is largely based on the characteristics of coal and rock destruction caused by its low temperature to achieve the purpose of increasing permeability. The temperature field study is very important in liquid nitrogen cold soaking. In order to study the spatiotemporal characteristics of the internal temperature field inside coal under the liquid nitrogen cold soaking, the overall heat transfer law of coal is discussed. Based on the theory of heat transfer, this paper discusses the heat transfer equation of coal under the liquid nitrogen cold soaking. A cold shock simulation experiment is performed on the coal specimens during the liquid nitrogen cold soaking by the COMSOL software, and the temperature field change of the coal specimens during the liquid nitrogen cold soaking are obtained. In addition, the simulation results are compared with the experimental results of coal specimens under the liquid nitrogen cold soaking to verify the rationality of the theory and simulation analysis. The results show that the temperature field of coal specimens propagates in the form of waves under the liquid nitrogen cold soaking, which gradually decrease with increasing distance. The closer the dried coal specimens are to the liquid nitrogen boundary surface, the greater the temperature impact speed and the shorter the time required to reach a steady state. Both the surface of the coal specimen and its internal temperature change curve can be divided into three typical phases: the accelerated cooling phase, the decelerated cooling phase, and the low-temperature maintenance phase. The laboratory test results have a good correspondence with the numerical simulation results, which show that it is feasible to use numerical simulation to study the temperature field change law of coal and rock under liquid nitrogen cold soaking.
Shumin Liu; Xuelong Li; Dengke Wang. Numerical simulation of the coal temperature field evolution under the liquid nitrogen cold soaking. Arabian Journal of Geosciences 2020, 13, 1 -10.
AMA StyleShumin Liu, Xuelong Li, Dengke Wang. Numerical simulation of the coal temperature field evolution under the liquid nitrogen cold soaking. Arabian Journal of Geosciences. 2020; 13 (22):1-10.
Chicago/Turabian StyleShumin Liu; Xuelong Li; Dengke Wang. 2020. "Numerical simulation of the coal temperature field evolution under the liquid nitrogen cold soaking." Arabian Journal of Geosciences 13, no. 22: 1-10.
The deformation and fracture of surrounding rock in deep underground engineering have the characteristics of time mutation and space continuity. In order to monitor and provide early warning of the dynamic deformation and fracture characteristics of deep surrounding rock, a real‐time digital displacement measuring instrument was developed in this paper. The proposed device represented a kind of surrounding rock deformation and fracture monitoring method, which had the continuous and real‐time advantages. Based upon the simulation experiments, the dynamic deformation and fracture of deep roadway surrounding rock were measured synchronously using the digital displacement measuring instrument testing system (DDMITS) and the V‐STARS measurement system. Comparative measurement results indicated that the DDMITS had a higher reliability. The deformation of roadway surrounding rock gradually increased with the increase of loading. The roof deformation and caving changing patterns in coal seam mining were studied using similar simulation experiments based on the DDMITS. The vertical displacement response of rock strata was more obvious than the horizontal displacement. There was a sharp increase in the vertical displacement during the collapse of the rock strata. Additionally, the vertical displacement velocity showed fluctuations. Meanwhile, the fluctuations in the vertical displacement acceleration increased significantly. The DDMITS could achieve full‐field measurement and the noncontact measurement of three‐dimensional deformation.
Rui Zhou; Jiankun Xu; Chao Wang; Xuelong Li. Dynamic deformation and fracture characteristics of a deep roadway surrounding rock based on the machine vision monitoring method. Energy Science & Engineering 2020, 9, 343 -356.
AMA StyleRui Zhou, Jiankun Xu, Chao Wang, Xuelong Li. Dynamic deformation and fracture characteristics of a deep roadway surrounding rock based on the machine vision monitoring method. Energy Science & Engineering. 2020; 9 (3):343-356.
Chicago/Turabian StyleRui Zhou; Jiankun Xu; Chao Wang; Xuelong Li. 2020. "Dynamic deformation and fracture characteristics of a deep roadway surrounding rock based on the machine vision monitoring method." Energy Science & Engineering 9, no. 3: 343-356.
Liquid nitrogen freeze–thaw has been used in oil, shale gas and coalbed methane exploitation as an efficient fracturing technology. This paper aimed to study the effect of different coal ranks and liquid nitrogen soaking times on the temperature distribution of coal samples, and to explore the temperature evolution mechanism of different coal ranks during liquid nitrogen soaking. For these objectives, the temperature change process, thermophysical parameters and infrared spectrum of different coal ranks under liquid nitrogen soaking were tested using, respectively, (a) liquid nitrogen soaking temperature measurement, (b) laser thermal instrument and (c) Fourier transform infrared spectrometer. The results showed that the temperature curves of coal samples under liquid nitrogen soaking were divided into an accelerated cooling stage I, a decelerated cooling stage II, and a maintained low-temperature stage III. As the number of liquid nitrogen soaking increased, the time required to reach low-temperature Stage III gradually shortened. During the rise in coal sample temperature, it increased with time in accordance with a logarithmic function. The order of absolute values of maximum heating/cooling speed was lignite > bituminite > anthracite. The higher coal rank is, more oxygen-containing functional groups were removed by coalification. The less content of oxygen-containing functional groups led to closer molecular structure, which resulted in smaller thermal conductivity and ultimately caused slower temperature transfer. The study results are of important guides to understand further the action process and mechanism of liquid nitrogen soaking on coal.
Shumin Liu; Xuelong Li; Dengke Wang; Dongming Zhang. Experimental Study on Temperature Response of Different Ranks of Coal to Liquid Nitrogen Soaking. Natural Resources Research 2020, 30, 1467 -1480.
AMA StyleShumin Liu, Xuelong Li, Dengke Wang, Dongming Zhang. Experimental Study on Temperature Response of Different Ranks of Coal to Liquid Nitrogen Soaking. Natural Resources Research. 2020; 30 (2):1467-1480.
Chicago/Turabian StyleShumin Liu; Xuelong Li; Dengke Wang; Dongming Zhang. 2020. "Experimental Study on Temperature Response of Different Ranks of Coal to Liquid Nitrogen Soaking." Natural Resources Research 30, no. 2: 1467-1480.
Gas occurrence in coal seams shows zonation, and the outburst risk prediction index is significantly affected by coal seam gas. For different coal mine, the sensitivity of prediction index of outburst risk is inconsistent, and the different area of the same coal mine can present different sensitivities to the same index. In this study, we measured the industrial analysis of coals and determined the degree of outburst risk of each coal seam using coal samples with the particle size of 1 ∼ 3 mm. The relationships between the equilibrium gas pressure and gas desorption index of drill cuttings, between the desorption index of drill cuttings and the adsorption pressure, and between the critical values of the indexes of drill cuttings were also analyzed using the fuzzy clustering method. Based on the analysis of the particle size distribution of coal samples, the influence of grain size on the critical value of the drill cuttings desorption index was studied. The results showed that the critical values of the desorption index of drill cuttings were different under different adsorption equilibrium gas pressures, and those critical values increased with increasing adsorption equilibrium gas pressure. The desorption index of drill cuttings and adsorption equilibrium gas pressure had a linear relationship, and the higher the degree of outburst risk was, the greater the slope of the fitting function and the smaller the intercept; under the same gas pressure of adsorption equilibrium, there was a linear relationship between Δh2 and K1, and the higher the outburst risk of coal seam was, the smaller the slope of the fitting function and the greater the intercept. The drill cuttings desorption index Δh2 was more sensitive than the index K1. Under the same test pressure, the smaller the particle size of the coal samples was, the greater the value of desorption index of drill cuttings and the higher the outburst risk of coal seam. The research results have significant theoretical importance and practical value for the prediction and prevention of coal and gas outbursts in coal mines with similar occurrence conditions of coal seams.
Fakai Wang; Yunpei Liang; Zhongguang Sun; Lei Li; Xuelong Li. Determination of the sensitivity index and its critical value for outburst risk prediction: A case study in Fuxiang mine, China. Adsorption Science & Technology 2020, 38, 502 -527.
AMA StyleFakai Wang, Yunpei Liang, Zhongguang Sun, Lei Li, Xuelong Li. Determination of the sensitivity index and its critical value for outburst risk prediction: A case study in Fuxiang mine, China. Adsorption Science & Technology. 2020; 38 (9-10):502-527.
Chicago/Turabian StyleFakai Wang; Yunpei Liang; Zhongguang Sun; Lei Li; Xuelong Li. 2020. "Determination of the sensitivity index and its critical value for outburst risk prediction: A case study in Fuxiang mine, China." Adsorption Science & Technology 38, no. 9-10: 502-527.
The consistent coefficient f of coal is a comprehensive index of the ability to resist the damage of external forces determined by various properties of coal. In the Chinese coal industry, it is listed as one important basic index of the four single indexes to judge the risk of coal and gas outburst. At present, the consistent coefficient f can only be determined by the dropping hammer method in the laboratory after the coal sample is collected on the working surface, and cannot be directly determined under coal mines. But the dropping hammer method is relatively cumbersome to operate, and the determination process is easily affected by the operation of the experimenters, so it cannot achieve the purpose of rapid prediction of coal and gas outburst danger. Therefore, a new method for rapidly determining the consistent coefficient f of coal based on the pulverization method is proposed, the principle of this method and the specific determination steps are given. And the optimal combination scheme of the key parameters of coal sample pulverization is established by the orthogonal test, which are given as follows: the initial particle size of the coal sample is 6 ~ 7 mm, the pulverization speed is 8000 rpm, the coal sample mass is 150 g, and the pulverization time is 10 s. Based on the analysis of pulverization data of the original coal samples collected from more than sixty coal mines in eleven major coal-producing areas with different geographical distribution in China, the experimental results show that the logarithmic fitting relationship is shown between the ƒ value and the mass ratios of the coal particles under different particle size after coal samples pulverized. With the coal particle size increasing, the fitting correlation degree gradually decreases. Among them, the fitting correlation degree between the mass ratio of coal particles below 0.5 mm particle size and the f value is the highest, and the correlation coefficient R2 is 91.7%. Based on the findings, the model for rapidly determining the consistent coefficient f of coal based on the pulverization method is established. And the consistent coefficient ƒ determined by this new method is very close to the ƒ value determined by the dropping hammer method. The absolute value of the error is within the range of 0 ~ 0.06, and the absolute value of the relative error is controlled within 10%, about 7.9%. This new method realizes rapid determination of f value of coal, overcomes the factors affecting the accuracy of determination by the dropping hammer method widely used at present, has the characteristics of simple and convenient operation, fast and accurate determination, and can meet the actual determination requirements under various conditions. The research results lay a strong research foundation for directly and rapidly determining the consistent coefficient ƒ of coal under coal mines.
Jiangong Li; Xuelong Li; Jie Hu. Research on the rapid determination technology of the consistent coefficient f of coal based on the crushing method. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 2020, 1 -18.
AMA StyleJiangong Li, Xuelong Li, Jie Hu. Research on the rapid determination technology of the consistent coefficient f of coal based on the crushing method. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. 2020; ():1-18.
Chicago/Turabian StyleJiangong Li; Xuelong Li; Jie Hu. 2020. "Research on the rapid determination technology of the consistent coefficient f of coal based on the crushing method." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects , no. : 1-18.
Low‐concentration gas is one of the most realistic and reliable supplementary or alternative energy sources of conventional natural gas, which has a wide range of applications. However, this gas is flammable and explosive during pipeline transportation and easily causes an explosion. In order to achieve safe transmission, the explosion characteristics and propagation law of low‐concentration gas are systematically studied through a large‐scale pipeline experimental system. We found that the peak pressure of low‐concentration gas explosion in pipeline has a quadratic function relationship with the propagation distance. Moreover, the peak pressure of gas explosion initially decreases from the explosion source, and then a turning point appears after a certain distance of propagation, which is followed by a sharp increase of peak pressure of gas explosion. The explosion pressure becomes maximum at the outlets of a pipeline. The arrival time of explosion flame is logarithmically relevant to propagation distance, while the speed of flame propagation gradually increases along with the increase of propagation distance. The flame propagation is faster at the exit point. In addition, the diameter of pipeline has also an important influence on the explosion propagation process of low‐concentration gas. So, the larger the diameter, the higher the explosion pressure. The explosion pressure of DN700 pipeline is obviously higher than that of DN500, and the explosion pressure rises faster; the speed of flame propagation of gas explosion in DN700 pipeline is also higher than that in DN500 pipeline. This study provides a theoretical reference for the prevention and control of explosion accidents in low‐concentration gas pipelines.
Lei Li; Zhigang Zhang; Peng Liu; KeQuan Wang; Jun Zhang; Xuelong Li. Experimental study of low‐concentration gas explosion in large‐scale pipeline. Energy Science & Engineering 2020, 8, 2129 -2140.
AMA StyleLei Li, Zhigang Zhang, Peng Liu, KeQuan Wang, Jun Zhang, Xuelong Li. Experimental study of low‐concentration gas explosion in large‐scale pipeline. Energy Science & Engineering. 2020; 8 (6):2129-2140.
Chicago/Turabian StyleLei Li; Zhigang Zhang; Peng Liu; KeQuan Wang; Jun Zhang; Xuelong Li. 2020. "Experimental study of low‐concentration gas explosion in large‐scale pipeline." Energy Science & Engineering 8, no. 6: 2129-2140.
Mine fires are becoming a serious issue as the intensity of mining increases, especially in deep mines. Loose coal gob has a hidden ignition location and a high possibility of spontaneous combustion, which makes fire prevention difficult. Therefore, based on the theory of gas seepage and the characteristics of loose coal, a model of air leakage and spontaneous combustion in gob is established in this paper. Using working face #10414 in the Yangliu coal mine as an example, the relationship between the three spontaneous coal combustion (CSC) zones and the three stress zones is analyzed and verified by combining a FLAC3D simulation with field monitoring. In addition, the influence of advancing speed on the CSC is discussed, and suggestions for fire prevention are presented. The results show that the variation in the calorific value of the CSC with increasing degree of looseness of the residual coal in the gob forms an arch‐shape. There is a one‐to‐one relationship between the distribution of the three stress zones and the three CSC zones. In addition, as the advancing speed increases, the contact time between the loose coal body and the air decreases and the possibility of CSC decreases. This study provides a scientific basis for fire prevention and control in mines.
Nan Li; Xuelong Li; Cai Shu; Wenlong Shen; Miao He; Jingjing Meng. Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob. Energy Science & Engineering 2019, 8, 689 -701.
AMA StyleNan Li, Xuelong Li, Cai Shu, Wenlong Shen, Miao He, Jingjing Meng. Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob. Energy Science & Engineering. 2019; 8 (3):689-701.
Chicago/Turabian StyleNan Li; Xuelong Li; Cai Shu; Wenlong Shen; Miao He; Jingjing Meng. 2019. "Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob." Energy Science & Engineering 8, no. 3: 689-701.
Nowadays, the water jet technique has been more frequently used for coal bed methane stimulation. As the ultimate component of the water jet system, the nozzle has important influence on the rock breaking ability of water jet. To optimize the nozzle, a simplified model for impinging water jet was established. The effects of geometric structure (cylindrical, conical, and conical‐straight) and parameters (outlet diameter d, conical angle α, and length L) on the flow field of the impinging water jet are simulated through computational fluid dynamics software Fluent14.0. Besides, the effects of inlet pressure (Pin) and target distances (S) on the jet dynamics are also discussed based on the simulation results. The results show that the jet dynamic parameters including dynamic pressure, velocity, and impinging pressure vary with different nozzles. The jet dynamic parameters linearly increase with the inlet pressure, while they first increase then decrease with the increase in target distance. Additionally, the optimal nozzle designed based on the numerical simulation was used in the field test, and the results indicate that this technique can effectively improve the gas drainage efficiency.
Xuelin Yang; Lipeng He; Tingkan Lu; Yanbao Liu; Xuelong Li; Jie Cao; Guang Luo; Huiming Yang. Optimization and field application of water jet for coal bed methane stimulation. Energy Science & Engineering 2019, 7, 3186 -3203.
AMA StyleXuelin Yang, Lipeng He, Tingkan Lu, Yanbao Liu, Xuelong Li, Jie Cao, Guang Luo, Huiming Yang. Optimization and field application of water jet for coal bed methane stimulation. Energy Science & Engineering. 2019; 7 (6):3186-3203.
Chicago/Turabian StyleXuelin Yang; Lipeng He; Tingkan Lu; Yanbao Liu; Xuelong Li; Jie Cao; Guang Luo; Huiming Yang. 2019. "Optimization and field application of water jet for coal bed methane stimulation." Energy Science & Engineering 7, no. 6: 3186-3203.
Since most coalfields in China are commonly characterized by high gas content and low permeability, there is an urgent need to improve coal seam permeability and further enhance coal bed methane (CBM) extraction efficiency. As an emerging fracturing technology, the CO2 gas fracturing (CGF) technology has been widely used because of its advantages of low cost, environmental protection and high fragmentation efficiency. In order to improve the fracturing ability of CGF technique and optimize the release orifices of discharge head, computational fluid dynamics model was used in this paper to simulate the flow fields of dynamic pressure of gas jet released from the orifices with different structures and other geometrical parameters. The results show that the orifice structure has a great influence on the flow field of gas jet, but little influence on the magnitude of the dynamic pressure. Besides, the maximum dynamic pressure of gas jet linearly decreases with the increase in the number of release orifices. Based on a series of simulation results, the discharge head which has single group of orifices with structure c, diameter of 24 mm can be identified as the best choice for fieldwork. Then, two field experiments were conducted in Pingdingshan and Changping coal mines to evaluate the enhanced CBM extraction efficiency by CGF. The results indicate that the CGF can effectively create a large number of cracks in a large range around the fracturing borehole in the coal seam and further significantly improve the permeability. And the CBM extraction efficiency can be improved to a higher level from a lower level and maintained for a long time. Besides, the effective influence radii caused by CGF in Pingdingshan and Changping coal mines are 15.19 m and 12.5 m, respectively. Compared with other fracturing techniques, the CGF technique has a promising application prospect.
Xuelin Yang; Guangcai Wen; Tingkan Lu; Bo Wang; Xuelong Li; Jie Cao; Genshuai Lv; Guanghua Yuan. Optimization and Field Application of CO2 Gas Fracturing Technique for Enhancing CBM Extraction. Natural Resources Research 2019, 29, 1875 -1896.
AMA StyleXuelin Yang, Guangcai Wen, Tingkan Lu, Bo Wang, Xuelong Li, Jie Cao, Genshuai Lv, Guanghua Yuan. Optimization and Field Application of CO2 Gas Fracturing Technique for Enhancing CBM Extraction. Natural Resources Research. 2019; 29 (3):1875-1896.
Chicago/Turabian StyleXuelin Yang; Guangcai Wen; Tingkan Lu; Bo Wang; Xuelong Li; Jie Cao; Genshuai Lv; Guanghua Yuan. 2019. "Optimization and Field Application of CO2 Gas Fracturing Technique for Enhancing CBM Extraction." Natural Resources Research 29, no. 3: 1875-1896.
Coal and rock mass constitute a type of porous medium. This study investigated the influence of temperature impact on the mechanical properties and acoustic emission (AE) characteristics of coal. A mechanism analysis was performed from the perspective of microstructure. The results show that the temperature impact causes the development of pores and cracks in the coal, which reduces the strength of coal. The elastic modulus of coal generally decreases with increasing temperature gradient. AE parameters increase with the increase in the load and reach the maximum value at the peak stress. AE parameters and cumulative parameters decrease with increasing temperature gradient. Not only does temperature impact change the fracture structure of the coal surface, but also the internal fracture structure of the coal is significantly affected. After temperature impact, the cracks expand and new cracks are initiated, and the fracture volume of the coal increases. Temperature impact causes the volume and specific surface area of small pores and meso-pores in coal to increase, and promotes the opening of the necking pores within the coal. The impact causes macro-pores to penetrate through to form cracks, which increases the transport of coal gas and significantly improves the permeability of coal. The thermal stress generated by coal under temperature impact is greater than its tensile strength, which promotes the cracking of coal, along with the initiation, widening, extension, and expansion of crack networks, which significantly change the fracture structure of coal. The research results lay a certain theoretical and experimental foundation for further study of mechanical properties of coal affected by liquid nitrogen.
Shumin Liu; Xuelong Li; Dengke Wang; Mingyang Wu; Guangzhi Yin; Minghui Li. Mechanical and Acoustic Emission Characteristics of Coal at Temperature Impact. Natural Resources Research 2019, 29, 1755 -1772.
AMA StyleShumin Liu, Xuelong Li, Dengke Wang, Mingyang Wu, Guangzhi Yin, Minghui Li. Mechanical and Acoustic Emission Characteristics of Coal at Temperature Impact. Natural Resources Research. 2019; 29 (3):1755-1772.
Chicago/Turabian StyleShumin Liu; Xuelong Li; Dengke Wang; Mingyang Wu; Guangzhi Yin; Minghui Li. 2019. "Mechanical and Acoustic Emission Characteristics of Coal at Temperature Impact." Natural Resources Research 29, no. 3: 1755-1772.
Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts—the lower key structure, the middle soft interlayer, and the upper key structure—are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 105 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.
Wenlong Shen; Meng Wang; ZhengZheng Cao; Faqiang Su; Hua Nan; Xuelong Li; Shen; Wang; Cao; Su; Nan; Li. Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study. Energies 2019, 12, 3016 .
AMA StyleWenlong Shen, Meng Wang, ZhengZheng Cao, Faqiang Su, Hua Nan, Xuelong Li, Shen, Wang, Cao, Su, Nan, Li. Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study. Energies. 2019; 12 (15):3016.
Chicago/Turabian StyleWenlong Shen; Meng Wang; ZhengZheng Cao; Faqiang Su; Hua Nan; Xuelong Li; Shen; Wang; Cao; Su; Nan; Li. 2019. "Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study." Energies 12, no. 15: 3016.
In this study, a stress-oriented experiment of gas-containing coal extrusion was performed by establishing an experimental system integrating gas injection, loading, and electrical testing. Then, the apparent resistivity images in different stages of gassy coal extrusion evolution were obtained. Finally, multi-parameter electrical characteristic parameters were extracted, and the variation and characterization significance of characteristic parameters were analyzed. The results show that the overall values of apparent resistivity images decrease in the gas adsorption equilibrium and stress loading stages. After the extrusion occurs, the values grow remarkably; in addition, there exist abnormal resistance values in some areas, which is consistent with the distribution of coal fractures. The fundamental reason for this phenomenon lies in the changed conductive channel within gassy coal. Moreover, average and maximum values of apparent resistivity both decrease first before they increase, whereas the current and spontaneous potential both rise first and then fall, of which the current changes more obviously. These changes, which characterize the evolution process of gassy coal extrusion, can provide theoretical guidance and experimental basis for geophysical exploration of gas dynamic disasters in coal and rock.
Peng Chen; Tao Yang; Xuexi Chen; Yongjie Liu; Xuelong Li; Kexue Zhang. Experimental study on electrical characteristics of gassy coal during extrusion process in different stage. Arabian Journal of Geosciences 2019, 12, 430 .
AMA StylePeng Chen, Tao Yang, Xuexi Chen, Yongjie Liu, Xuelong Li, Kexue Zhang. Experimental study on electrical characteristics of gassy coal during extrusion process in different stage. Arabian Journal of Geosciences. 2019; 12 (14):430.
Chicago/Turabian StylePeng Chen; Tao Yang; Xuexi Chen; Yongjie Liu; Xuelong Li; Kexue Zhang. 2019. "Experimental study on electrical characteristics of gassy coal during extrusion process in different stage." Arabian Journal of Geosciences 12, no. 14: 430.
In this study, we designed an experimental system of surface potential during coal adsorption of gas to examine the characteristics of surface potential in this process. The results suggested that surface potential was generated in this process and that it was enhanced with the passage of time. In adsorption cycles, the higher the pressure, the greater the surface potential signals, and they increase exponentially. Thereby, research on surface potential during gas adsorption on coal holds great theoretical significance for understanding the physical properties of coal.
Yongjie Liu; Xuelong Li; Jiangong Li; Peng Chen; Tao Yang. Experimental study on variation laws of coal surface potential during gas adsorption. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 2019, 43, 634 -643.
AMA StyleYongjie Liu, Xuelong Li, Jiangong Li, Peng Chen, Tao Yang. Experimental study on variation laws of coal surface potential during gas adsorption. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. 2019; 43 (5):634-643.
Chicago/Turabian StyleYongjie Liu; Xuelong Li; Jiangong Li; Peng Chen; Tao Yang. 2019. "Experimental study on variation laws of coal surface potential during gas adsorption." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 43, no. 5: 634-643.
Understanding the stress‐cracks‐permeability evolution law inside coal body under cyclic loading is significant to optimize the gas extraction technology and gas disasters prevention technology. In order to explore the influence of mining cyclic stress on the mechanical behavior and permeability variation of gas‐bearing seams, the experiments on permeability evolution, deformation law, and acoustic emission (AE) characteristics of coal samples under cyclic loading with different loading stress level and different loading frequency were carried out. These results indicate that the higher loading stress level, the shorter the fatigue life of coal sample. With the increase of the loading stress level, the change rate of permeability became higher and the relation curves between permeability and loading cycles developed from “U” to “V,” which can be defined and divided into three stages, for example, decrease stage, stable stage, and increase stage. And the permeability in the decrease stage can be modeled as a power function of the loading cycles, while the permeability in the increase stage can be modeled as an exponential function of the loading cycles. Besides, the loading stress level has a significant on the permeability, while the loading frequency has little impact on the permeability evolution. In the process of coal deformation under cyclic loading, the strain development of strain coal samples was in the shape of inverted “S,” while the variation of the peak values of corresponding AE ring counts presented “U” type. In addition, there was a good correlation between the permeability and the AE parameters of coal samples, which provide a new sight into the dynamic variation process of the stress‐cracks‐permeability evolution inside coal body under cyclic loading.
Xuelin Yang; Jie Cao; Xiaoyang Cheng; Yanbao Liu; Xuelong Li; Zhongguang Sun; Junjie Guo. Mechanical response characteristics and permeability evolution of coal samples under cyclic loading. Energy Science & Engineering 2019, 7, 1588 -1604.
AMA StyleXuelin Yang, Jie Cao, Xiaoyang Cheng, Yanbao Liu, Xuelong Li, Zhongguang Sun, Junjie Guo. Mechanical response characteristics and permeability evolution of coal samples under cyclic loading. Energy Science & Engineering. 2019; 7 (5):1588-1604.
Chicago/Turabian StyleXuelin Yang; Jie Cao; Xiaoyang Cheng; Yanbao Liu; Xuelong Li; Zhongguang Sun; Junjie Guo. 2019. "Mechanical response characteristics and permeability evolution of coal samples under cyclic loading." Energy Science & Engineering 7, no. 5: 1588-1604.
With mining technology and mechanization degree being improving, fully mechanized caving mining technology (FCM) has become a main method for thick coal seam extraction in China. However, roof-coal caving characteristics in turn restrict its recovery efficiency, especially for the coal seam with complicated structure (CCS), that is, the coal seam comprises hard or soft coal and gangue. In order to explore the key factors influencing the roof-coal caving and recovery characteristics, related research work has been conducted as follows: firstly, a mechanical model of CCS has been established, which indicates the strength of the coal and gangue will directly affect the roof-coal recovery. Meanwhile, based on the geological settings of Qinyuan coal mine, numerical simulation on roof-coal caving law under different thicknesses of hard or soft coal and gangue has been performed using UDEC software. The results show that the maximum principal stress will increase with the increase of mining depth, making the roof-coal to break easily. Furthermore, the range of the plastic zone of the top coal and the damage degree of the top coal increase with the increase of mining depth. Physical modeling results show that when an extraction-caving ratio is 1, the number of times the coal arch forms is 0.43 at every caving, up to a maximum of 3; the number of times coal arch forms with an extraction-caving ratio of 2 is 4.65 times larger than that with an extraction-caving ratio of 1. The probability of coal arch formation with an extraction-caving ratio of 3 is minimal, about 0.4, which is due to that the arch span is large and the curvature is small, so it is difficult to form a stable arch structure. According to the mechanical characteristics of roof-coal in Qinyuan coal mine, deep-hole blasting technique has been used to reduce the fragments of roof-coal crushed. The results show that this technique can effectively improve the recovery of roof-coal.
Yunpei Liang; Lei Li; Xuelong Li; KeQuan Wang; Jinhua Chen; Zhongguang Sun; Xuelin Yang. Study on Roof-Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining. Shock and Vibration 2019, 2019, 1 -20.
AMA StyleYunpei Liang, Lei Li, Xuelong Li, KeQuan Wang, Jinhua Chen, Zhongguang Sun, Xuelin Yang. Study on Roof-Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining. Shock and Vibration. 2019; 2019 ():1-20.
Chicago/Turabian StyleYunpei Liang; Lei Li; Xuelong Li; KeQuan Wang; Jinhua Chen; Zhongguang Sun; Xuelin Yang. 2019. "Study on Roof-Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining." Shock and Vibration 2019, no. : 1-20.