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Innovation point
(1) It clarifies the internal relationship between the annual coal output and the number of impact ground pressure mines in the mainland since the founding of the People's Republic of China, and points out that with the improvement of the level of coal mining equipment and the improvement of mine operator management and technical level, the mining capacity of coal resources has increased significantly, which has directly led to the increase in mining intensity, which has resulted in more impact ground pressure mines. Under the same mining intensity, the dynamic disaster area generated by the superposition of deep proto rock stress and mining stress is significantly greater than that produced by the superposition of shallow parts, indicating that deep mining is more likely to induce dynamic disasters such as impact pressure.
(2) From the realistic perspective of impacting ground pressure mine in order to achieve production, three different mining intensity mining schemes are designed under the constraint of production capacity, and numerical simulation and theoretical analysis are used to analyze the characteristics of coal rock mining stress, energy release and overburden collapse structure under different mining intensity, and the results show that the top and bottom plate stress, advanced support pressure and impact hazard of the whole layer mining are greater than those of stratified mining, and there is obvious strain energy peak forward shift phenomenon in the former. It is also pointed out that the increase in the thickness of the working surface will cause the rotation angle and fracture degree of the key block to increase, improve the possibility of slippage instability and rotation instability, and the acceleration of the propulsion speed will increase the possibility of rotation instability, and it is easier to induce the overlying rock layer to break and release a large amount of energy, thereby improving the impact risk.
(3) On the basis of analyzing the current coal mine production capacity determination method and deficiency, the mining disturbance characteristics of the working surface of the deep buried coal seam under different mining intensity are revealed, and the reasonable mining intensity of the mine is determined in reverse according to the mining disturbance characteristics under different mining intensity, and then the method of determining the mine production capacity is mainly included, mainly including reducing the production capacity and implementing the mechanical modification of coal and rock, and the mining method of Mengcun Coal Mine is optimized, which provides a scientific basis for guiding the prevention and control of mine impact pressure disaster.
Characteristics of mining disturbances and their production capacity under different mining intensities of impact ground pressure mines
Authors: Cui Feng1,2,3, Zhang Tinghui1,2, Lai Xingping1,2, Wang Sujian4, Chen Jianqiang5, Qian Deyu6
Units: 1. School of Energy, Xi'an University of Science and Technology, 2. Key Laboratory of Mine Mining and Disaster Prevention in Western China, Ministry of Education, Xi'an University of Science and Technology, 3. Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, 4. Shaanxi Coal Industry Chemical Technology Research Institute Co., Ltd., 5. Xinjiang Energy Co., Ltd. of State Energy Group; 6. School of Mining Engineering, China University of Mining and Technology
Background
After long-term large-scale development, the shallow coal resources of the mainland are increasingly depleted, the center of gravity of coal production has gradually shifted to the deep, and the coal resources of the mainland have entered the deep mining on a large scale, but due to the complex rock overburden structure, high-intensity mining, insufficient experience in impact pressure prevention and control in the deep mining process, etc., which have led to frequent impact ground pressure accidents in the deep mining process. For the definition of deep, Academician Xie Heping pointed out that deep is not depth, but a mechanical state, and the concept of deep should comprehensively reflect the stress level, stress state and surrounding rock properties of deep. According to incomplete statistics, there are 47 wells with a depth of more than 1,000 m in the mainland, with a total output of 94.56 million t and an average burial depth of 1,100 m. In addition to the above-mentioned ultra-1,000-meter deep wells, in the past 5a, 16 pairs of new deep mines have been added to the mainland, including 12 mines in The Binchang and Yonglong Mining Areas of Shaanxi Province, the Hujirt Mining Area, and the Shanghai Temple Mining Area, etc., and these deep mining areas will undertake the main coal production tasks of the mainland in the future. After entering the deep mining, the deep rock is in the complex mechanical environment of "three highs and one disturbance", resulting in disasters such as impact pressure in the exploitation of deep resources. In view of the prevention and control of impact pressure disasters, Jiang Yaodong and others pointed out that the main prevention and control technologies include: optimizing the mining layout, modifying the coal rock in situ in the areas with impact risk, increasing the strength of support and improving the support method. For specific mines, the mining layout of the mine has been basically determined, and the prevention and control measures of impact ground pressure mainly include regulating the mining intensity and active pressure relief modification, but on the whole, the reasons for high stress concentration and elastic energy accumulation are mainly high-intensity mining, such as too fast mining speed, too large mining height, too large working surface size, etc. As for the definition of high-intensity mining, mainland scholars have carried out a lot of research.
In the past, scholars have enriched the definition of high strength from multiple dimensions such as geological conditions, coal seam storage conditions, mining technology, development level of coal mining equipment, and rock mechanics experiments. However, the relationship between mine production capacity and mining intensity is not considered, for example, in order to deeply learn the lessons of impact ground pressure accidents such as "10·20" in Shandong Energy Longyun Coal Industry, the State Coal Regulatory Administration issued the "Notice of the State Coal Mine Safety Supervision Bureau on Strengthening the Prevention and Control of Coal Mine Impact Ground Pressure" in May 2019, stipulating that the production scale of impact ground pressure mines shall not exceed 8 million tons/a, further limiting the mining intensity of the working surface from the perspective of impact ground pressure coal mine production capacity. Tan Yunliang et al. analyzed the relationship between different depths, different plastic zone widths, different degrees of propulsion and the kinetic energy generated, and pointed out that the larger the mining scale, the higher the kinetic energy generated, and reducing the mining speed and reducing the advance is conducive to reducing the kinetic energy generated. Wang Bo et al. pointed out that the faster the mining speed under the same mining time, the longer the basic top suspension distance, the more elastic energy accumulated before the break, the closer the peak of the advanced support pressure is to the coal wall, the larger the peak, the easier to exceed the critical value of the impact ground pressure, and the energy release promotes the impact of the coal wall on the working surface. Comprehensive analysis shows that the greater the mining strength of the mining working surface, the higher the probability of inducing the emergence of impact pressure. However, in order to complete the annual production index task, most coal mines only design the mining intensity level according to historical experience and the level of on-site equipment, and do not consider the characteristics of mining disturbance under different mining intensities, which is easy to induce dynamic disasters such as impact ground pressure, so it is urgent to carry out research on mining disturbance characteristics under different mining intensities.
Excerpt
Mining disturbance is the root cause of deformation, impact and instability of deep coal rock mass, and the characteristics of mining disturbance are closely related to mining intensity. After entering the deep mining, the number of impact pressure mines continues to increase with the increase of mining intensity, and it is of great significance to study the mining disturbance characteristics under different mining intensities of impact pressure mines, and then determine the reasonable mining intensity according to the mechanical response characteristics of mining coal rock.
Taking the Binchang Mining Area of a typical impact ground pressure mining area as an example, numerical simulation and theoretical analysis are used to analyze the mining disturbance characteristics of coal rock mining stress, energy release and overburden collapse structure under different mining intensity, analyze the mining disturbance characteristics at different thrust speeds and mining thicknesses, evaluate the impact hazard of mining coal bodies at different mining intensities, and discuss the application of mining disturbance characteristics in mine capacity regulation and mining method optimization. The findings suggest:
(1) The annual coal production is proportional to the number of impact ground pressure mines, and the possibility of impact ground pressure in deep mines is significantly higher than that of shallow mines.
(2) The top and bottom plate stress, advanced support pressure and impact hazard of the whole layer mining are greater than those of the stratified mining, and there is a significant phenomenon of peak strain energy forward in the former.
(3) The increase in the thickness of the working surface will cause the rotation angle and fracture degree of the key block to increase, improve the possibility of slipping instability and rotation instability, and the acceleration of the propulsion speed will increase the possibility of rotation instability, and it is easier to induce the overlying rock layer to break and release a large amount of energy, thereby improving the impact risk.
(4) The mining disturbance characteristics of the working surface of the deep buried coal seam under different mining intensities are revealed, the reasonable mining intensity of the mine is determined in reverse according to the mining disturbance characteristics under different mining intensity, and the mine production capacity is determined, and the mining method of Mengcun Coal Mine is optimized based on the mining disturbance characteristics, which provides a scientific basis for guiding the prevention and control of mine impact pressure disaster.
Image
Mainland coal production and number of impact ground pressure mines
Illustration of dynamic disaster areas with different stress levels
Overburden columnar
The working surface is fully mobilized and the two belts develop at height
Characteristics of base plate stress changes in different mining schemes
The evolution of advanced support pressure of different mining schemes
Partial enlargement after the end of the layered recovery of No. 4 coal
Evolution trend of strain energy density at different thrust distances
Impact risk index for different mining schemes
2 key block structure movement force
Variation curves of fracture and rotation angle under different mining thicknesses
Effect of propulsion speed on 2 key block rotations
Reasonable capacity determination method for mines
About the Author
Cui Feng, male, born on December 3, 1986, from Xinxiang, Henan, Ph.D., professor, doctoral supervisor. Shaanxi Provincial Young Science and Technology Rising Star, Shaanxi Province "High-level Talents Special Support Program" young top-notch talents, won the 10th National Colleges and Universities Mining and Petroleum Safety Engineering Field Outstanding Young Scientific and Technological Talents Nomination Award, served as a member of the Fourth Coal Industry Technology Committee Power Disaster Early Warning and Prevention Expert Committee, Chinese Society of Rock Mechanics and Engineering Soft Rock Engineering and Deep Disaster Control Branch Director, Chinese Rock Mechanics and Engineering Society Rock Crushing Engineering Professional Committee Member, etc. His research achievements have won 4 first prizes and 3 second prizes at the provincial and ministerial levels. He has published more than 30 academic papers, including more than 20 SCI/EI searches, 1 paper selected as the top academic paper of China's high-quality scientific and technological journals, 4 books published, and 9 authorized invention patents.
Research Directions
Comprehensive discharge mining of extra-thick coal seams, dynamic disaster control, multi-source disaster monitoring and intelligent analysis of mines
Key results
It is committed to the research on the mechanical response law and control of mining coal rock in the western region, exploring the common scientific problems of "three sudden and one impact" of coal mine power disasters, and establishing a dynamic disaster control technology system that integrates engineering design/mining disturbance control/coal rock modification three-dimensional linkage。 The research reveals the occurrence mechanism of dynamic disasters in sharply inclined extra-thick coal seams, develops the coupling cracking technology of sharply inclined extra-thick coal seams, proposes the scientific production capacity determination method of impact pressure mines, and develops the early warning and regulation technology of dynamic disasters based on the response ratio of mining and unloading, and the research results are applied in coal mines in Shaanxi, Xinjiang and other places, and good application results are achieved, which promotes the safe mining and stable supply of coal resources in the western region.
source:
Cui Feng,Zhang Tinghui,Lai Xingping,et al. Characteristics of mining disturbance and its production capacity under different mining intensities of impact ground pressure mines[J]. Journal of China Coal Society,2021,46(12):3781-3793.]
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