sustainability-logo

Journal Browser

Journal Browser

Sustainable Development of Coal Based Energy: Technology, Environment, Humanities, Economy, and Education

A topical collection in Sustainability (ISSN 2071-1050). This collection belongs to the section "Resources and Sustainable Utilization".

Viewed by 68026

Editors

School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Interests: mine pressure and strata control; mine water resources utilization; coal and gas co-mining; abandoned mine reuse
Special Issues, Collections and Topics in MDPI journals
School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Interests: underground longwall mining; mining-induced strata movement control; green mining technology; mining-induced environment sustainability
Special Issues, Collections and Topics in MDPI journals
School of Energy and Mining Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Interests: mine water control; shaft failure prevention
School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China
Interests: mining engineering; surface subsidence; green or sustainable mining; mining damage and environmental protection; ground pressure and strata control

Topical Collection Information

Dear Colleagues,

Coal-based energy is a reasonable indicator of economic health in some developed economies, such as the USA, Canada, Australia, etc., and especially in developing countries, such as China, India, etc. Sustainable developments of coal mining technologies, coal mining damage control, environment protection and energy humanities are still interesting topics playing a key role in energy safety and climate change, especially intelligent and green mining technologies, the protection and utilization of mine water resources, restoration of the ecological environment in mining area, reuse of abandoned mines, coal mine solid waste backfilling, greenhouse gas emission control, etc. For these reasons, we propose a wide-ranging topic that can be summarized as “Sustainable Development of Coal Based Energy: Technology, Environment, Humanities, Economy, and Education”. This highly interdisciplinary theme can, therefore, involve a wide scientific audience, from geologists to mining, environmental and management engineers, as well as economists and educationists.

Dr. Cun Zhang
Prof. Dr. Fangtian Wang
Dr. Shiqi Liu
Dr. Erhu Bai
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • underground green mining technology
  • underground reservoir system
  • coal mine gas extraction technology
  • backfilling mining technology
  • exploitation and utilization of mine water
  • mine geothermal resource exploitation
  • natural gas hydrate exploitation
  • mining-induced strata movement control
  • mining-induced environment protection
  • ecological restoration of mining area
  • coal-based energy humanities
  • coal-based energy economy
  • coal-based energy education
  • abandoned coal mine carbon capture

Published Papers (54 papers)

2023

Jump to: 2022

20 pages, 1289 KiB  
Article
Research on the Impact of the Digital Economy on Carbon Pollution Based on the National Big Data Comprehensive Pilot Zone in China
by Mingguang Liu and Gaoyang Li
Sustainability 2023, 15(21), 15390; https://doi.org/10.3390/su152115390 - 28 Oct 2023
Viewed by 719
Abstract
The digital economy (DE) is increasingly recognized as a principal driver of high-quality economic development. With the dual carbon goals of carbon peak and carbon neutrality, it is essential to urgently discuss whether the DE can also provide an aid to restrain carbon [...] Read more.
The digital economy (DE) is increasingly recognized as a principal driver of high-quality economic development. With the dual carbon goals of carbon peak and carbon neutrality, it is essential to urgently discuss whether the DE can also provide an aid to restrain carbon pollution. For this reason, the purpose of this paper is to examine the influence of the DE on urban carbon pollution and its underlying mechanism, utilizing balance panel data for Chinese cities from 2012 to 2021. Additionally, this study adopts the quasi-natural experiment in the National Big Data Comprehensive Pilot Zone to empirically analyze this relationship using the Difference-in-Differences (DID) and mediating effect models. The findings indicate that the DE can significantly decrease carbon pollution, exhibiting a clear carbon pollution reduction effect. These conclusions remain valid even after implementing various robustness tests. This examination of the action mechanism reveals that it is effective for the DE to mitigate urban carbon pollution by enhancing energy efficiency and attracting foreign investment. Further analysis of heterogeneity reveals that it is more effective for the DE to reduce carbon pollution in the non-resource-based cities, large cities, eastern regions, and cities with high urbanization levels as compared to the resource-based cities, small or mega cities, central and western regions, and cities with a low level of urbanization. These findings not only offer robust objective evidence for the positive influence of the DE on carbon pollution reduction, but also present valuable policy implications for minimizing carbon pollution and enhancing environmental quality. Full article
Show Figures

Figure 1

25 pages, 12736 KiB  
Article
Simulation Experimental Investigations into the Mechanical Response and Failure Mechanisms of Coal–Rock Combinations
by Wenbing Guo, Yuhang Hu and Dongtao Wu
Sustainability 2023, 15(20), 15175; https://doi.org/10.3390/su152015175 - 23 Oct 2023
Viewed by 709
Abstract
The stability of the composite structures formed by coal pillar and roof rock is of great significance to safe production and sustainable development of coal mines. In order to explore the failure and instability mechanisms of coal–rock combinations (CRCs) with varying rock-to-coal height [...] Read more.
The stability of the composite structures formed by coal pillar and roof rock is of great significance to safe production and sustainable development of coal mines. In order to explore the failure and instability mechanisms of coal–rock combinations (CRCs) with varying rock-to-coal height ratios, uniaxial compression tests of CRCs with varying rock-to-coal height ratios were performed via laboratory tests and numerical simulation of particle flow tests, and the mechanical response and failure mechanisms of CRC were comprehensively investigated with regard to their strength, failure characteristics, crack and energy evolution. The results show that the stress thresholds for the crack initiation, uniaxial compressive strength, and elastic modulus of CRCs rose with the decreasing coal-to-rock height ratio, and the fragmentation degree of the coal samples increased with rock-to-coal height ratio. The instability and failure of CRCs are the result of the interaction between the strength of sandstone and coal at the interface and the strength of sandstone and coal far from the interface region; in addition, they are influenced by the distribution range of microfractures during the loading process. The point effect and slip effect formed by coal failure cause sandstone split failure and shear failure, respectively. The number of cracks, macrocrack length, total input energy, elastic strain energy, and dissipated strain energy all reduce first and then increase as the coal thickness reduces. CRCs still have a certain load-bearing capacity in the post-peak stage, mainly due to their strong load-bearing skeleton structure and the friction between particles in the fracturing area, which can resist external forces. Full article
Show Figures

Figure 1

20 pages, 10361 KiB  
Article
Research on the Influence of Backfilling Mining in an Iron Mine with Complex Mining Conditions on the Stability of Surface Buildings
by Huaibin Li, Zhenpeng Guo, Xinzhu Hua, Bibo Dai, Xuemin Zeng and Yuemao Zhao
Sustainability 2023, 15(20), 14733; https://doi.org/10.3390/su152014733 - 11 Oct 2023
Viewed by 548
Abstract
The safe and efficient extraction of ore bodies under buildings contributes to the continued exploitation and utilization of mineral resources. To effectively reduce the mining-induced disturbance caused to surface buildings, the Vertical Crater Retreat (VCR) delayed backfilling method was applied at the Wuji [...] Read more.
The safe and efficient extraction of ore bodies under buildings contributes to the continued exploitation and utilization of mineral resources. To effectively reduce the mining-induced disturbance caused to surface buildings, the Vertical Crater Retreat (VCR) delayed backfilling method was applied at the Wuji iron mine according to mining theory and engineering experience, and the surface deformation under buildings was investigated through numerical simulation and on-site monitoring. The results show that stress concentration occurs at the top of the ore body and in surrounding rocks between ore veins, and the direction of the principal stress coincides with that of the main bearing capacity of the rock mass. With the increasing distance between the surrounding rock and the ore body, the stress disturbance in the surrounding rock attenuates gradually. The surface subsidence and deformation caused by ore mining exhibits the same northwest trend as the strike of the ore body, and the surface deformation in the X direction is greater than that in the Y direction. The surface deformation of the mining area near the 1# air shaft, Wuji village, steam autoclave workshop of the brick factory, and 1# substation is relatively large, while the surface subsidence, horizontal deformation, inclination, and curvature are all smaller than the critical values allowed for buildings and structures. This research provides a theoretical basis and engineering guidance for the prevention and control of surface deformation during mining under buildings and structures. Full article
Show Figures

Figure 1

19 pages, 1026 KiB  
Article
Effects of Higher Education on Green Eco-Efficiency and Its Optimization Path: Case Study of China
by Yue Xu, Zihao Xu, Dayu Zhai and Yanyu Li
Sustainability 2023, 15(18), 13428; https://doi.org/10.3390/su151813428 - 07 Sep 2023
Viewed by 778
Abstract
Based on the annual panel data of 30 provinces in China, this paper evaluates the green eco-efficiency of each province via factor decomposition and analyzes the impact of higher education on green eco-efficiency using the two-way fixed effect model, considering economic development, urban [...] Read more.
Based on the annual panel data of 30 provinces in China, this paper evaluates the green eco-efficiency of each province via factor decomposition and analyzes the impact of higher education on green eco-efficiency using the two-way fixed effect model, considering economic development, urban scale, industrial structure, foreign investment and government regulation as control factors. The results show that the penetration of higher education has a significant positive impact on green eco-efficiency. Heterogeneity analysis suggests that the positive impact of undergraduate and postgraduate education is significant, and this impact increases with the increasing levels of education; however, the influence of junior college education is not significant. Higher education in eastern China significantly affects green eco-efficiency in a positive manner, while the relationship between the two is not significant in the central and western regions. The test of mediating effects further shows that technological innovation has a partial mediating effect, while environmental attention does not show a mediating effect in the influencing path of higher education on green eco-efficiency. Accordingly, this paper proposes certain implications regarding green-related courses, transformation from consciousness to practice, and incorporation of green education in higher education systems. Full article
Show Figures

Figure 1

18 pages, 7559 KiB  
Article
Investigation of the Time-Dependent Stability of a Coal Roadway under the Deep High-Stress Condition Based on the Cvisc Creep Model
by Zhiliang Yang, Cun Zhang and Donghui Yang
Sustainability 2023, 15(17), 12673; https://doi.org/10.3390/su151712673 - 22 Aug 2023
Viewed by 612
Abstract
Creep is a fundamental property that naturally exists in some types of rock, which is significant for the long-term stability of roadways during the mining process. In this paper, the long-term strength of coal and rock were determined via laboratory experiments, and a [...] Read more.
Creep is a fundamental property that naturally exists in some types of rock, which is significant for the long-term stability of roadways during the mining process. In this paper, the long-term strength of coal and rock were determined via laboratory experiments, and a Cvisc elasto-viscoplastic model was adopted and introduced in FLAC3D, based on the 31101 transport roadway in the Hongqinghe Coal Mine, to investigate the influence of creep on the stability of a deep high-stress roadway. The test results show that the long-term strength of 3-1 coal and sandy mudstone was 18.65 MPa and 39.95 MPa, respectively. The plastic zone, the deformation, and the damage of the roadway’s surrounding rock displayed an obvious increase after being excavated for 720 d as the creep model was chosen. The plastic zone failure was modeled with shear-p (1090.7 m3), shear-n (381.7 m3), tension-n (98.4 m3), and tension-p (30.8 m3). The damage value had an obvious increment of 21.2% (0.053), and the deformation increased in the order of the two sidewalls (1978 mm), the roof (907 mm), and the floor (101 mm). The creep of the roadway can be divided into three stages: the accelerating stage, the decaying stage, and the stable stage. The creep speed of each stage is greatly affected by the presence or absence of anchor spray support: the creep speed of the bare roadway roof, sidewalls, and floor stability was 1.01, 1.02, and 0.12 mm/d, respectively. After anchor spray support, the creep velocity, correspondingly, decreased to 0.69, 0.37, and 0.12 mm/d, and the amount of surrounding rock damage decreased from 0.302 to 0.243. This indicates that the anchor spray support can significantly reduce the creep effect of the roadway. The Cvisc creep model was verified to be reliable and can provide guidance for deep high-stress coal roadway support. Full article
Show Figures

Figure 1

18 pages, 742 KiB  
Article
Analysis of Energy Laboratory Safety Management in China Based on the System-Theoretic Accident Model and Processes/System Theoretic Process Analysis STAMP/STPA Model
by Shuheng Zhong, Jinping Du and Xidi Jiang
Sustainability 2023, 15(15), 11505; https://doi.org/10.3390/su151511505 - 25 Jul 2023
Viewed by 817
Abstract
Laboratory safety in colleges and universities has received wider attention as a critical annual inspection by the Ministry of Education. The laboratory environment is complex and diverse, with many hazard factors. To effectively prevent the occurrence of laboratory emergencies in universities, the STAMP/STPA [...] Read more.
Laboratory safety in colleges and universities has received wider attention as a critical annual inspection by the Ministry of Education. The laboratory environment is complex and diverse, with many hazard factors. To effectively prevent the occurrence of laboratory emergencies in universities, the STAMP/STPA model is used to analyze the safety of energy laboratory safety management in a resource-based university. Between 2021 and 2022, we carried out laboratory safety inspection and field observation for a mining resource university in China, and identified 16 unsafe control actions in the field of energy laboratory safety management in the university, and identified ten critical causal factors leading to unsafe control actions. Combining the actual situation of the mining resource university, the short-term countermeasures and long-term countermeasures to improve laboratory safety management are proposed to guarantee the university’s laboratory safety management. Moreover, the research results have suggestions for the construction and development of laboratory safety management at similar universities. Full article
Show Figures

Figure 1

13 pages, 3102 KiB  
Article
Numerical Simulation Study on the Evolution Law of Stress and Crack in Coal Seam Hydraulic Fracturing
by Shouguo Yang, Ning Xu and Xiaofei Zhang
Sustainability 2023, 15(14), 11351; https://doi.org/10.3390/su151411351 - 21 Jul 2023
Cited by 1 | Viewed by 701
Abstract
Hydraulic fracturing as a conventional reservoir permeability enhancement technique can effectively increase the production of coalbed methane, and it is important to study the stress and crack evolution law to evaluate the effect of coalbed fracturing and optimize the construction process. To accurately [...] Read more.
Hydraulic fracturing as a conventional reservoir permeability enhancement technique can effectively increase the production of coalbed methane, and it is important to study the stress and crack evolution law to evaluate the effect of coalbed fracturing and optimize the construction process. To accurately derive the evolution characteristics of stress and the propagation form of cracks during hydraulic fracturing of coal seams, a numerical model of hydraulic fracturing was established based on a three-point bending test of coal samples using the finite-discrete element method (FDEM). Based on a coal seam in a mining area in southwest China, a hydraulic fracturing model was established, and the reliability of the numerical model was verified by comparing the numerical simulation with the analytical expression. The model was used to study the evolution of stress and cracks with time during hydraulic fracturing, and the influence of elastic modulus and permeability on the evolution of stress and cracks was investigated. The results show that stress and cracks in the process of hydraulic fracturing belong to a mutual feeding mechanism during evolution, and the effective permeability range of fracturing is an ellipse with the crack as the long axis enclosed by the effective stress field. The greater the elastic modulus of the coal seam, the greater the crack initiation pressure and the shorter the crack initiation time, and a coal seam with a high elastic modulus is more likely to form complex cracks. The change in coal seam permeability has little effect on the initiation pressure and initiation time, but the crack propagation path is obviously different, and a coal seam with low permeability is more favorable to hydraulic fracturing. Full article
Show Figures

Figure 1

22 pages, 24805 KiB  
Article
Research on J2 Evolution Law and Control under the Condition of Internal Pressure Relief in Surrounding Rock of Deep Roadway
by Dongdong Chen, Zhiqiang Wang, Zaisheng Jiang, Shengrong Xie, Zijian Li, Qiucheng Ye and Jingkun Zhu
Sustainability 2023, 15(13), 10226; https://doi.org/10.3390/su151310226 - 28 Jun 2023
Viewed by 701
Abstract
In order to solve the support problem of deep soft crushed coal roadway, a concentrated cavern in a mining station of a mine is taken as the test object. Based on the analysis and summary of the field observation data and the law [...] Read more.
In order to solve the support problem of deep soft crushed coal roadway, a concentrated cavern in a mining station of a mine is taken as the test object. Based on the analysis and summary of the field observation data and the law of rock pressure appearance, a new technology of pressure relief anchoring with the main body of “initiative support + borehole pressure relief” is proposed. This new technology will carry out strong active support in the shallow part of the surrounding rock and excavate a row of low-density large-diameter pressure relief boreholes in the deep coal body of the roadway ribs. The numerical analysis model is established by FLAC3D, and the second invariant of deviatoric stress (J2) is used as the analysis index to elaborate the influence of different borehole parameters on the pressure relief effect of roadway surrounding rock. The results show that different borehole parameters have different effects on roadway pressure relief, that is, borehole depth > borehole length > borehole spacing. After the borehole process is used to relieve the pressure of the surrounding rock, the deformation of the mining roadway side in the subsequent observation process is always controlled within the range of 100 mm, and the shallow surrounding rock support system is effectively protected. The comprehensive control effect is very obvious. Therefore, the field practice proves that the supporting technology can effectively solve the problem of large deformation support of similar roadway surrounding rock. Full article
Show Figures

Figure 1

17 pages, 5152 KiB  
Article
Bituminous Coal Sorption Characteristics and Its Modeling of the Main Coal Seam Gas Component in the Huaibei Coalfield, China
by Gang Wu, Zhiwei Ye, Lei Zhang and Jun Tang
Sustainability 2023, 15(12), 9822; https://doi.org/10.3390/su15129822 - 20 Jun 2023
Cited by 1 | Viewed by 759
Abstract
Knowledge of the gas sorption and permeability characteristics of a coal provides an essential basis for the evaluation of coalbed methane reserves and their recoverability. Thus, the gas excess sorption capacities of the main gas component of coal seam gas (CSG) in bituminous [...] Read more.
Knowledge of the gas sorption and permeability characteristics of a coal provides an essential basis for the evaluation of coalbed methane reserves and their recoverability. Thus, the gas excess sorption capacities of the main gas component of coal seam gas (CSG) in bituminous coal samples derived from the Xutuan Coal Mine in the Huaibei Coalfield, in the Anhui Province of China, were measured using a volumetric method. The results showed that under the same equilibrium pressure, the order of excess sorption capacity was CO2 > CH4 > N2. Furthermore, the sorption capacity ratios of coal from the Xutuan Mine for CO2, CH4, and N2 were approximately 6.0:2.3:1. It was also demonstrated that the sorption capacity during depressurization was always larger than that of the adsorption process, which is indicative of desorption hysteresis. The behaviors of three adsorption models, Langmuir, BET, and D-R, all of which include two parameters, are considered in this paper. The different gas sorption measurement data were fitted by the three models. For the bituminous coal samples, the fits of the D-R equation of all three different gases are higher than 0.99, the fits of the Langmuir equation are higher than 0.985, while the fits of the BET equation for CH4 and N2 absorption are higher than 0.95. However, the fits of the BET equation for CO2 absorption are only about 0.5. Coal sorption has an apparent influence on coal permeability; the permeability of the same coal sample to N2, CH4, and CO2 gases was tested and analyzed. The result shows that the permeability of CO2 was found to be lower than that of other coal seam gas constituents, CH4 and N2, due to their different adsorption abilities. Full article
Show Figures

Figure 1

17 pages, 5257 KiB  
Article
Energy Accumulation Characteristics and Induced Rockburst Mechanism of Roadway Surrounding Rock under Multiple Mining Disturbances: A Case Study
by Zhenkai Ma, Sheng Li and Xidong Zhao
Sustainability 2023, 15(12), 9595; https://doi.org/10.3390/su15129595 - 15 Jun 2023
Cited by 1 | Viewed by 689
Abstract
The source of energy release when rockburst occurs must be determined to understand the mechanisms underlying disaster formation and achieve accurate prevention and control. Although previous research has systematically investigated the energy source underlying rockburst from different perspectives, issues such as an unclear [...] Read more.
The source of energy release when rockburst occurs must be determined to understand the mechanisms underlying disaster formation and achieve accurate prevention and control. Although previous research has systematically investigated the energy source underlying rockburst from different perspectives, issues such as an unclear understanding of the energy accumulation state and inaccurate positioning of the energy release source remain to be resolved. In this study, the “1·17” major roof accident in the Danshuigou Mine was used as the background to evaluate and analyze the stress environment and energy accumulation characteristics of roadway surrounding rock under multiple mining disturbances, and the results showed that a super energy package occurs in the surrounding rock of the mining roadway. Subsequently, the evolution process of energy in this region and the mechanism of induced rockburst were elaborated. The results showed that the degree of stress concentration in the surrounding rock of the roadway will increase several times as the number of mining disturbances increases. Under the influence of multiple mining disturbances, the maximum principal stress peak of the surrounding rock of the roadway can reach 5–10 times the maximum principal stress value outside the mining-affected area. A large amount of elastic energy was accumulated in the rock surrounding the roadway, and super-high-density energy packages were formed locally. The maximum energy density value reached 50–185 times the value observed in areas outside the mining-affected zone. Thus, rockburst may be induced when the large amount of energy accumulated in the super energy package is suddenly and violently released; moreover, the degree of energy accumulation in the super energy package is likely closely related to the magnitude of rockburst. These results have important theoretical significance and application value for clarifying the mechanism of rockburst and improving the effectiveness of rockburst prediction and prevention. Full article
Show Figures

Figure 1

20 pages, 3915 KiB  
Article
Investigation into Occurrence Mechanism of Rock Burst Induced by Water Drainage in Deep Mines
by Bo Wang, Guorui Feng, Fuxing Jiang, Junpeng Ma, Chao Wang, Zhu Li and Wenda Wu
Sustainability 2023, 15(11), 8891; https://doi.org/10.3390/su15118891 - 31 May 2023
Cited by 1 | Viewed by 823
Abstract
Confined aquifers widely exist in the strata of the Ordos mining area. Water drainage before mining is an effective measure to avoid water inrush disasters caused by the connectivity between mining-induced roof fractures and aquifers. However, rock burst disasters occur frequently in the [...] Read more.
Confined aquifers widely exist in the strata of the Ordos mining area. Water drainage before mining is an effective measure to avoid water inrush disasters caused by the connectivity between mining-induced roof fractures and aquifers. However, rock burst disasters occur frequently in the mining process of many water drainage working faces. The statistics show that the surrounding rock of nine water drainage working faces in five mines has suffered different degrees of rock burst, which seriously restricts the safe, efficient production and sustainable development of ten-million-ton modern mines in China. Based on this, taking the 22,106 longwall working face (LW22106) of the Shilawusu Mine, Ordos, as the engineering background, this paper investigates the occurrence mechanism of water drainage on rock burst in the roof water-rich area by using theoretical analysis, similar material simulation, microseismic measurement and other methods. The main conclusions are as follows: (1) After the drainage of the water-rich area, the pressure relief zone, pressurized zone and pressure stabilization zone are formed in sequence from the center to both sides. The width of the pressure relief zone is consistent with that of the water-rich area, and the width of the pressurized zone is about 35 m on one side. (2) When the mining is passing the pressurized zone, the coal rock mass is under the joint influence of gravity stress, mining disturbance stress and drainage transfer stress. The superimposed stress generally exceeds 2.5 times the uniaxial compressive strength (UCS) of the coal rock mass, and the maximum reaches 3.24 times, far exceeding the critical value of rock burst (1.5 times UCS), which is the main reason to induce rock burst. (3) The dynamic change in the rock burst risk areas before and after drainage in water-rich area no. 4 has been predicted, and the number of risk areas increases from 4 before drainage to 13 after drainage. Since the stress superposition effect differs due to different mining speeds, it is proposed that the dynamic regulation of mining speed in the front and at the back of the drainage area is an effective and efficient method for rock burst prevention and control. The research results will provide a theoretical basis and technical support for the prevention and control in the roof water-rich area of deep mines. Full article
Show Figures

Figure 1

20 pages, 3086 KiB  
Article
CO2 Flow Characteristics in Macro-Scale Coal Sample: Effect of CO2 Injection Pressure and Buried Depth
by Huping Wang, Zhao Wang, Haikui Yin, Chao Jin, Xiaogang Zhang and Langtao Liu
Sustainability 2023, 15(10), 8002; https://doi.org/10.3390/su15108002 - 14 May 2023
Viewed by 841
Abstract
Experimental studies have confirmed the permeability reduction of coal samples upon the adsorption of CO2. However, these studies were carried out under limited experimental conditions. In this study, CO2 flow behaviors in a macro-scale coal sample were numerically simulated using [...] Read more.
Experimental studies have confirmed the permeability reduction of coal samples upon the adsorption of CO2. However, these studies were carried out under limited experimental conditions. In this study, CO2 flow behaviors in a macro-scale coal sample were numerically simulated using a coupled gas flow, mechanical deformation, and sorption-induced deformation finite element model. The simulation results show that the effect of the reduction of effective stress on the enhancement of permeability is greater than the negative effect of permeability reduction due to CO2 adsorption for low injection pressures. CO2 pressure development in the sample increases with increasing injection pressure due to the enhanced advection flux for sub-critical CO2 injections, while for super-critical CO2 injections, CO2 pressure development, as well as concentrations in the sample, decreases compared to sub-critical CO2 injections because of greater density and viscosity of super-critical CO2 as well as coal matrix swelling induced by the adsorption of super-critical CO2. Increasing axial stress (buried depth) obstructs CO2 migration in the sample due to the increased effective stress, and this effect is more influential for low injection pressures, which indicates that high CO2 injection pressures are preferred for CO2 sequestration in deep coal seams. Full article
Show Figures

Figure 1

16 pages, 7567 KiB  
Article
Difference in Surface Damage between Deep and Shallow Mining of Underground Coal Resources in China
by Weitao Yan, Junting Guo and Shaoge Yan
Sustainability 2023, 15(9), 7296; https://doi.org/10.3390/su15097296 - 27 Apr 2023
Cited by 1 | Viewed by 1166
Abstract
The mining of underground coal resources often results in extensive damage to the ground surface, particularly in China, which has a large amount of coal resources. However, the laws of surface damage caused by the mining of deep and shallow underground coal resources [...] Read more.
The mining of underground coal resources often results in extensive damage to the ground surface, particularly in China, which has a large amount of coal resources. However, the laws of surface damage caused by the mining of deep and shallow underground coal resources are relatively different. This study analyzes the difference in surface damage induced by deep and shallow mining and its mechanism by field measurement and similar material simulation experiments. Surface damage is mainly manifested in the form of cracks, which can be categorized as permanent and dynamic cracks. Permanent cracks occur above the mining boundary of shallow and deep coal mines. Dynamic cracks (including dynamic stretching cracks and stepped cracks) only appear above the goaf in shallow mining. This disparity is due to the fact that strata movement in deep mining occurs in a “three zones” mode, with the failure height of strata increasing with the mining degree in an “S” shape. However, rock strata movement in shallow mining follows a “two zones” mode, with the failure height of rock strata increasing exponentially with the mining degree. Thus, the rock strata are prone to slide and become unstable in the form of benched rock beams, producing dynamic cracks, such as stepped cracks on the surface. This research improves the existing mining subsidence theory and provides technical support for relevant mines to take targeted treatment measures. Full article
Show Figures

Figure 1

22 pages, 15153 KiB  
Article
The Floor Heave Mechanism and Control Technology of Gob-Side Entry Retaining of Soft Rock Floor
by Zexin Li, Yidong Zhang, Qi Ma, Yu Zheng, Guangyuan Song, Wanzi Yan, Yu Zhang and Lei Hu
Sustainability 2023, 15(7), 6074; https://doi.org/10.3390/su15076074 - 31 Mar 2023
Cited by 4 | Viewed by 1025
Abstract
Extensive soft-rock floor heave in gob-side entry retaining considerably restricts the efficient and sustainable production of the mine. The mechanical capacities of roadway roof and floor strata are discussed through laboratory tests by taking the N2301 fully caving surface auxiliary transport gate road [...] Read more.
Extensive soft-rock floor heave in gob-side entry retaining considerably restricts the efficient and sustainable production of the mine. The mechanical capacities of roadway roof and floor strata are discussed through laboratory tests by taking the N2301 fully caving surface auxiliary transport gate road of the Ancient City Coal Mine in the Lu’an Mining Area of Shanxi Province as an engineering background. The stress distribution law of gob-side entry in mining the working surface was explored based on numerical simulation. After that, the mechanical mechanism of floor heave was studied through theoretical analysis. High lead abutment pressure and horizontal stress were superimposed in front of the working surface to cause soft-rock floor heave. The bulk weight of the high overburden was unevenly transmitted to the two sides because of the roof cantilever structure of entry retaining in the rear of the working face. The roadway floor produced an asymmetric sliding force, which caused the occurrence of floor heave. The control technology of floor heave combining the pressure relief of floor blasting and roof cutting was proposed taking account of the mechanism of floor heave. Then, the stress environment of the surrounding rock was improved by the deep hole blasting of the floor. Gob-side roof cutting was used to reduce impact of the bulk weight of the overburden on the surrounding rock deformation of the roadway. A test was conducted after verifying the control effect of blasting pressure relief on roadway floor heave through a similar simulation. Field tests indicated that the maximum floor heave was 168 mm at 250 m in the rear of the working surface, and floor heave was controlled. This study offers a more scientifically sound theoretical reference for controlling floor heave in gob-side entry retaining, which can significantly advance the sustainable development of gob-side entry retaining technology in coal mining. Full article
Show Figures

Figure 1

17 pages, 4072 KiB  
Article
Construction and Application of an Intelligent Roof Stability Evaluation System for the Roof-Cutting Non-Pillar Mining Method
by Qizhi Chen, Baoping Zou, Zhigang Tao, Manchao He and Bo Hu
Sustainability 2023, 15(3), 2670; https://doi.org/10.3390/su15032670 - 02 Feb 2023
Cited by 4 | Viewed by 1575
Abstract
In order to sustainably use coal resources and reduce coal mine accidents, the stability evaluation of roadway roofs is particularly important. The existing methods of roof stability evaluation and control application are greatly disjointed, the relationship between roof stability evaluation and early warning [...] Read more.
In order to sustainably use coal resources and reduce coal mine accidents, the stability evaluation of roadway roofs is particularly important. The existing methods of roof stability evaluation and control application are greatly disjointed, the relationship between roof stability evaluation and early warning control is ignored, and an intelligent evaluation and calculation control system is lacking. Based on the successful application of the roof-cutting non-pillar mining method in various engineering geology and mining conditions, the roof stability evaluation system, mobile intelligent computing system, and engineering application research are carried out. An evaluation index system for roof stability in the roof-cutting non-pillar mining method is established, including the roof rock integrity and the roof-surrounding rock displacement. A comprehensive evaluation method for roof stability grades is proposed based on the coupling of evaluation index grading criteria and improved analytic hierarchy process (AHP) weight assignment. A handheld mobile intelligent platform for roof stability evaluation, roof hazard zone, and control suggestion is developed. The research results have been applied in the coal mine of Hecaogou with good outcomes. This intelligent stability evaluation system will provide an economical and effective approach to achieving sustainable use of coal resources. Full article
Show Figures

Figure 1

19 pages, 5310 KiB  
Article
Research on the Distribution Characteristics of the Bulking Coefficient in the Strike Direction of the Longwall Goaf Filled with Slurry
by Wenyu Lv, Tianqi Song, Wenzhe Gu, Fengqi Qiu, Panshi Xie and Kai Guo
Sustainability 2023, 15(3), 2508; https://doi.org/10.3390/su15032508 - 31 Jan 2023
Cited by 2 | Viewed by 957
Abstract
Coal gangue slurry filling is an important technical means for harmless and large-scale disposal of gangue under low-interference conditions, and is one of the most important ways to achieve green mining, which is in line with the national concept of green development. This [...] Read more.
Coal gangue slurry filling is an important technical means for harmless and large-scale disposal of gangue under low-interference conditions, and is one of the most important ways to achieve green mining, which is in line with the national concept of green development. This paper systematically expounds the technical background and scientific connotations of the birth of slurry filling, clarifies the key technology and process principles of slurry filling, and constructs the lag distance and optimization method of slurry filling based on the bulking coefficient. In order to explore the distribution law of the bulking coefficient of the overburden broken zone in the mining process, UDEC numerical simulation and similar simulations were used to analyze the movement law of a coal seam roof and the distribution characteristics of the bulking coefficient. The results show that with the evolution of the spatial structure of the overlying strata of the goaf, the subsidence of the coal seam roof decreases from the bottom to the top, and finally becomes stable. In the advancing direction of the working face, the bulking coefficient decreases continuously, and shows certain zoning characteristics. With the mining, it moves forward periodically with dynamic changes. In the strike direction, it can be divided into three areas: the natural accumulation area, the load-affected area and the gradual compaction area. Finally, the lag distance of slurry filling is determined to be 60 m, and the effect of adjacent grouting filling is good in the field test. Full article
Show Figures

Figure 1

13 pages, 6507 KiB  
Article
Mechanical Properties and Damage Characteristics of Coal-Based Solid Waste Paste Filling Materials with Different Moisture Content
by Meng Wang, Xiang He and Ke Yang
Sustainability 2023, 15(2), 1523; https://doi.org/10.3390/su15021523 - 12 Jan 2023
Cited by 2 | Viewed by 1069
Abstract
It has been proven that it is a feasible treatment method to prepare paste filling material from coal-based solid waste to fill underground goaf. Based on the complexity of the goaf environment, especially the influence of humidity on paste filling materials, this paper [...] Read more.
It has been proven that it is a feasible treatment method to prepare paste filling material from coal-based solid waste to fill underground goaf. Based on the complexity of the goaf environment, especially the influence of humidity on paste filling materials, this paper prepared paste filling materials with a mass concentration of 80% by using coal gangue and fly ash, and carried out a uniaxial compression test of coal-based solid waste paste filling materials under four different water-bearing states. The experimental results show that: (1) The binary primary equation fits well the variation trend of paste filling strength with water content. With the increase of moisture content, the compressive strength of paste filling material gradually decreases, and the higher the moisture content, the more obvious the influence on the strength of paste filling. (2) The damage evolution equation and constitutive equation of paste filling materials with different moisture content were established. With the increase of strain, the influence of moisture content on the damage of paste filling material decreases gradually, and the moisture content can promote the damage development of paste filling material to a certain extent. (3) The influence mechanism of moisture content on coal based-solid waste paste filling material is discussed from the three aspects of physical effect, structural effect and chemical effect, which provides a direction for further research on the influence mechanism of moisture content on filling strength. The research on the failure mechanism of coal-based solid waste paste filling and the safety production of the mine can be used as a theoretical support. Full article
Show Figures

Figure 1

17 pages, 4276 KiB  
Article
Study on the Mechanism of a Hanging Roof at a Difficult Caving End in a Fully-Mechanized Top Coal Caving Face
by Hongtao Liu, Cheng Hao, Zijun Han, Qinyu Liu, Haozhu Wang, Jialu Liang and Dandan Zhang
Sustainability 2023, 15(1), 812; https://doi.org/10.3390/su15010812 - 02 Jan 2023
Viewed by 1108
Abstract
During the mining process of fully-mechanized caving faces, the roof of the roadway behind the working face easily forms an arched-shape hanging roof structure with the working face pushed forward, which results in potential hazards such as gas accumulation and large-scale roof collapse. [...] Read more.
During the mining process of fully-mechanized caving faces, the roof of the roadway behind the working face easily forms an arched-shape hanging roof structure with the working face pushed forward, which results in potential hazards such as gas accumulation and large-scale roof collapse. Based on the actual situation of a hanging roof at a difficult caving end in fully-mechanized top coal caving faces, through borehole exploration, surrounding rock displacement observation, bolt stress monitoring, theoretical formula calculation, and numerical simulation methods, the structure characteristics of the hanging roof at the end of the fully-mechanized caving face are studied. The ultimate failure depth and ultimate break distance of the hanging roof structure at the end of the working face are obtained, and its formation mechanism is analyzed. It is concluded that the hanging structure is formed by the following reasons: the lithology of sandy mudstone and fine sandstone above the top coal of the roadway is strong; the hanging roof structure is less affected by working-face mining; there is a result of insufficient rotary pressure of the upper mudstone while working together with the protective coal pillar and end support the caving step distance of the curved hanging roof structure is 10~13.55 m. Full article
Show Figures

Figure 1

2022

Jump to: 2023

16 pages, 5136 KiB  
Article
Failure Mechanism and Control Technology for Coal Roadway in Water-Rich Area
by Hao Fan, Xingang Niu and Shaobo Li
Sustainability 2023, 15(1), 410; https://doi.org/10.3390/su15010410 - 27 Dec 2022
Cited by 1 | Viewed by 1043
Abstract
Accurate analysis of failure mechanisms and scientific support for design of coal roadways in water-rich areas plays an important role in the long-term stability control of roadways. In this study, taking the water-rich 1044 return laneway in the Taoyuan Coal Mine of China [...] Read more.
Accurate analysis of failure mechanisms and scientific support for design of coal roadways in water-rich areas plays an important role in the long-term stability control of roadways. In this study, taking the water-rich 1044 return laneway in the Taoyuan Coal Mine of China as an example, laboratory experiments and field tests were performed to study the potential failure mechanisms of the roadway. It was found that the microcracks inside the coal body increase and strength of the coal decreases with the long-term influence of groundwater. The weak surrounding rock and high vertical in-situ stress were the main internal causes of roadway instabilities. Based on the potential failure mechanisms, a new optimal support design including bolt, cable, metal mesh, shotcrete, and grouting was proposed and detailed support parameters were introduced. A field experiment was performed with the new support, and surface deformations of the experimental roadway were monitored. Results show that the new support can reduce the deformation of the 1044 return laneway by nearly 90% compared with those of the original design. Support technology presented in this contribution provides a significant reference for the control of roadways in water-rich areas. Full article
Show Figures

Figure 1

15 pages, 7038 KiB  
Article
Coal Burst Prevention Technology and Engineering Practice in Ordos Deep Mining Area of China
by Weihui Pan, Yunpeng Li, Chuang Zhang, Xiaoshan Shi, Heng Cui, Bo Wang, Yang Li and Yue Wang
Sustainability 2023, 15(1), 159; https://doi.org/10.3390/su15010159 - 22 Dec 2022
Cited by 3 | Viewed by 1188
Abstract
With the coal mines in western China entering the field of deep mining, the problem of coal burst is becoming more and more serious. According to the characteristics of deep mining, it is an urgent problem that requires the development of an efficient [...] Read more.
With the coal mines in western China entering the field of deep mining, the problem of coal burst is becoming more and more serious. According to the characteristics of deep mining, it is an urgent problem that requires the development of an efficient and reasonable coal burst prevention and control plan to guide project practices. This study takes the typical deep mining area in Ordos as the research background, according to the stress state of the coal mining area and the load form of induced coal burst, which, in Ordos deep mining, is divided into the typical and atypical type. The former is caused by the superposition of high in situ stress and strong mining-induced stress, while the latter is due to the combination of high in situ stress, strong mining-induced stress, and external stress disturbances. Combined with theoretical analysis, numerical simulation, and field measurement, it is shown that the stress level of the Ordos deep mining area is higher than that of the shallow original rock, and the difference of the three-dimensional stress between coal and rock mass is greater. The concentration degree and influence range of mining-induced stress obviously increase. Coal and rock mass are more prone to instability and failure due to external disturbances. Based on the stress control theory, the prevention and control strategies of coal burst in different types of deep mining are put forward. In addition, the prevention and control technology system of coal burst in the Ordos deep mining area is established. The field engineering practice has been carried out to realize the efficient prevention and control of coal burst. Full article
Show Figures

Figure 1

14 pages, 3176 KiB  
Article
Evaluation of the Coordination Degree of Coal and Gas Co-Mining System Based on System Dynamics
by Shuheng Zhong and Dan Lin
Sustainability 2022, 14(24), 16434; https://doi.org/10.3390/su142416434 - 08 Dec 2022
Cited by 3 | Viewed by 1011
Abstract
Coal and gas co-mining is one of the green mining technologies in coal mines. Coal and gas co-mining can reduce environmental pollution and supply-side carbon emissions from the coal industry. It has an important role to play in achieving the goal of carbon [...] Read more.
Coal and gas co-mining is one of the green mining technologies in coal mines. Coal and gas co-mining can reduce environmental pollution and supply-side carbon emissions from the coal industry. It has an important role to play in achieving the goal of carbon peaking and carbon neutrality. The perfect state of safety production and economic efficiency is a “win-win” situation. Therefore, it is of great theoretical and practical importance to evaluate the safety and economic coordination of coal and gas co-mining systems. This study used a system dynamics approach to analyze and evaluate the coordination of coal and gas co-mining systems in a dynamic simulation. A case study was conducted using the Zhuxianzhuang coal mine as an example. The results showed that the coordination degree of the coal and gas co-mining system exhibited dynamic changes. The average value of the system coordination degree is 0.790, which is a good coordination degree. This demonstrates that the system dynamics method is feasible for evaluating the coordination degree of the coal and gas co-mining system. The system dynamics evaluation model can effectively simulate the dynamic changes of different variable factors in the co-mining system. Therefore, these research results can provide corresponding optimization recommendations for practical production needs. Full article
Show Figures

Figure 1

14 pages, 3922 KiB  
Article
Pumped Storage Hydropower in Abandoned Mine Shafts: Key Concerns and Research Directions
by Xin Lyu, Tong Zhang, Liang Yuan, Ke Yang, Juejing Fang, Shanshan Li and Shuai Liu
Sustainability 2022, 14(23), 16012; https://doi.org/10.3390/su142316012 - 30 Nov 2022
Cited by 4 | Viewed by 2229
Abstract
The quest for carbon neutrality raises challenges in most sectors. In coal mining, overcapacity cutting is the major concern at this time, and the increase in the number of abandoned mine shafts is a pervasive issue. Pumped storage hydropower (PSH) plants built in [...] Read more.
The quest for carbon neutrality raises challenges in most sectors. In coal mining, overcapacity cutting is the major concern at this time, and the increase in the number of abandoned mine shafts is a pervasive issue. Pumped storage hydropower (PSH) plants built in abandoned mine shafts can convert intermittent electricity into useful energy. However, studies on basic theories and key technologies are a pressing issue. Six key scientific problems have been identified in PSH development in abandoned mine shafts that are relevant to China’s national conditions, current resource structure, and relative status of energy storage technologies in China and other countries. It is proposed that the research on pumped storage should move closer to the direction of intelligence, stabilization, and greening, and the construction and development should gradually realize integration, completion, and coordination. The goal is to realize integrated, complete, and coordinated development of PSH in abandoned mine shafts, streamline national policies concerning PSH, drive the co-development of industry, education and research, and achieve the carbon neutrality targets set by China. Full article
Show Figures

Figure 1

16 pages, 4244 KiB  
Article
Characteristics and Formation Mechanism of Surface Residual Deformation above Longwall Abandoned Goaf
by Erhu Bai, Xueyi Li, Wenbing Guo, Yi Tan, Mingjie Guo, Peng Wen and Zhibao Ma
Sustainability 2022, 14(23), 15985; https://doi.org/10.3390/su142315985 - 30 Nov 2022
Cited by 2 | Viewed by 921
Abstract
With the rapid development of social economy in China, the contradiction between the wide distribution of abandoned goaf and the shortage of land for engineering construction is becoming increasingly prominent. The effective utilization of coal mining subsidence areas has become an effective measure [...] Read more.
With the rapid development of social economy in China, the contradiction between the wide distribution of abandoned goaf and the shortage of land for engineering construction is becoming increasingly prominent. The effective utilization of coal mining subsidence areas has become an effective measure to alleviate the poverty of construction land in mining areas and promote the green transformation of mining cities. The key to the scientific utilization of abandoned goaf is the prevention and control of surface residual deformation, which depends on the formation mechanism of surface residual deformation. Based on the regularity of mining-induced surface movement and deformation under different mining sizes, it is concluded that the full mining degree of working face is the primary condition for entering the surface recession period. The trapezoidal and periodic forward movement characteristics of mining-induced overburden destruction are analyzed. The regularity of upward transmission of mining-induced fissures with overburden destruction is clarified. The influencing factors of surface residual deformation are equivalent to the influencing factors of overburden structure and caved zone. The deformation characteristics of broken rock in the caved zone under different conditions (particle size, gradation, and water content) are analyzed. It is concluded that the surface residual subsidence near the boundary of the goaf is more significant than that in the middle of the goaf. It is revealed that the overburden structure at the boundary of the goaf and the re-compaction of the caved zone is the mechanism of surface residual deformation. The characteristics of surface residual deformation in abandoned goaf have been verified by field measurement, and it is pointed out that the surface residual deformation in abandoned goaf has long-term characteristics, which provides a theoretical basis for accurate prediction of surface residual deformation and rational utilization of abandoned goaf. Full article
Show Figures

Figure 1

22 pages, 4987 KiB  
Article
Which Provincial Regions in China Should Give Priority to the Redevelopment of Abandoned Coal Mines? A Redevelopment Potential Evaluation Based Analysis
by Yuliang Yang and Chaoqun Cui
Sustainability 2022, 14(23), 15923; https://doi.org/10.3390/su142315923 - 29 Nov 2022
Cited by 1 | Viewed by 800
Abstract
Abandoned mines have a double nature consisting of resources and assets, and their rational redevelopment is one of the most important practices of the recycling economy. To direct the layout of the regional abandoned mine redevelopment, this paper constructs a comprehensive assessment framework [...] Read more.
Abandoned mines have a double nature consisting of resources and assets, and their rational redevelopment is one of the most important practices of the recycling economy. To direct the layout of the regional abandoned mine redevelopment, this paper constructs a comprehensive assessment framework for abandoned mine redevelopment potential based on the driving force–state–response (DSR) model. It is quantitatively evaluated by three-dimensional cloud models, and the results are coupled using a four-quadrant approach. From the perspective of space control, this paper proposes classification principles of redevelopment potential and redevelopment sequence and summarizes the important policy implementations for each category. The paper studies the redevelopment potential of abandoned mines from the provincial perspective in 25 coal-producing provinces of China. The results indicate that not all areas with high resource potential are suitable for redevelopment. In the northern and western regions, the regional abandoned mines have high resource potential and strong redevelopment drivers. However, the spatial pattern of the suitability of the development conditions is not distributed in the same way as the resources. The distribution of the abandoned mine redevelopment potential reveals that the eastern and east-central regions should give priority to the construction of demonstration projects. Different driving force scenarios confirm that most provinces have no obvious driving factor preference, with a few exceptions. This evaluation model is established from a more comprehensive perspective and is a valuable aid for decision makers when arranging abandoned mine regeneration projects. Full article
Show Figures

Figure 1

20 pages, 9272 KiB  
Article
A Comparison of Research Methods to Determine the Sustainability of Mineral Resources in Henan Province Based on Cloud Analysis
by Shuang Gong, Shibin Yao, Furui Xi, Juan Liu, Xingyang Ren, Dengyun Niu, Jiaxing Ding, Hao Zhang, Jingkuo Wang and Shuai Wang
Sustainability 2022, 14(23), 15834; https://doi.org/10.3390/su142315834 - 28 Nov 2022
Viewed by 1011
Abstract
In order to improve the fuzzy comprehensive evaluation model of mineral resource sustainability and enhance its scientific and objective nature, in this paper, a cloud model-based risk assessment method is introduced to determine the sustainability of mineral resources in a comprehensive comparison, while [...] Read more.
In order to improve the fuzzy comprehensive evaluation model of mineral resource sustainability and enhance its scientific and objective nature, in this paper, a cloud model-based risk assessment method is introduced to determine the sustainability of mineral resources in a comprehensive comparison, while using a combination of subjective and objective weighting method combining improved hierarchical analysis and the entropy weighting method. Compared with the previous single-assignment evaluation method, the method used in this paper has the advantages of more reasonable determination of weights, more accurate results and better visualization. On this basis, the combined weight method, cloud model method and hierarchical fuzzy evaluation method are organically combined to conduct a comprehensive evaluation of the sustainability of mineral resources in Henan Province. The case analysis shows that the comprehensive evaluation results of the sustainability of mineral resources obtained according to the method are scientifically reasonable and have important reference value and promotion significance for quantitative research in related fields. Full article
Show Figures

Figure 1

18 pages, 4019 KiB  
Article
The Impact of Surface Water Seepage on Seismicity and Rockbursting in Mines
by Anatoly Kozyrev, Andrian Batugin, Jianping Zuo and Svetlana Zhukova
Sustainability 2022, 14(22), 15414; https://doi.org/10.3390/su142215414 - 20 Nov 2022
Cited by 2 | Viewed by 1516
Abstract
Retrospective analysis of data obtained from long-term monitoring of technogenic seismicity and rockbursts at the Apatitovy Tsirk and the Rasvumchorr Plateau deposits (Russia) showed that there is a significant (by 50% or more) increase in the number of geodynamic events during spring snowmelt [...] Read more.
Retrospective analysis of data obtained from long-term monitoring of technogenic seismicity and rockbursts at the Apatitovy Tsirk and the Rasvumchorr Plateau deposits (Russia) showed that there is a significant (by 50% or more) increase in the number of geodynamic events during spring snowmelt periods. An upswing of seismic activity within this rock massif occurs when following conditions are true: water reserve in the snow cover on the deposit area is more than 3 × 108 m3; snowmelt period exceeds 40 days; increase in water ingress rates continues for over 5 days and total water inflow volume exceeds the previous daily measurements by at least a factor of 2. Seismic activity of the massif starts to intensify after the snowmelt develops momentum. Major induced earthquakes occurred in the years when these conditions were met (for example, in 2005 there was a magnitude 2.3 earthquake; in 2009, M = 1.6 earthquake), and more than 1000 seismic events were recorded during the snowmelt period. It has been established that when mining reaches the depths of more than 500 m, seismic events during infiltration of atmospheric precipitation begin to occur from a depth of 100–200 m and are recorded to depths of about 900 m. A possible controlling factor of the seismic activation is the reactivation of tectonic faults, which occurs under conditions of the critically stressed state of the massif, due to a decrease in their normal compression during infiltration. Retrospective analysis of the factors contributing to a strong rockburst (K = 10–11) in 1990 at a bauxite mine in the South Urals shows that prior to this disaster there was an inrush of the Ai River waters into the mine workings through a large tectonic disturbance, which has not been previously taken into account when analyzing the mechanism of this geodynamic event. The intrusion of water into the fault located in the field of regional stresses and subsequent partial relief of its fault plane from normal stresses could have triggered the rockburst with fault-slip mechanism. The study of the relationship between amount of precipitation and the degree of water encroachment into the field, on the one hand, and seismicity, on the other hand, is needed to draw up recommendations on improving geodynamic and environmental safety of mining regions in order to ensure their sustainable development. Full article
Show Figures

Figure 1

19 pages, 12768 KiB  
Article
Overlying Strata Movement and Mine-Pressure Weakening Law of High-Efficiency Longwall Paste Backfilling of Thick Coal
by Qi Ma, Yidong Zhang, Yu Zheng, Zexin Li, Guangyuan Song and Lei Hu
Sustainability 2022, 14(22), 15356; https://doi.org/10.3390/su142215356 - 18 Nov 2022
Cited by 1 | Viewed by 1023
Abstract
This work focused on the serious coal compression under buildings, railways, and water bodies in central and eastern China; the wide range of rock formation damage during the collapse mining process; the high pressure of mines; and difficulties in controlling surface subsidence after [...] Read more.
This work focused on the serious coal compression under buildings, railways, and water bodies in central and eastern China; the wide range of rock formation damage during the collapse mining process; the high pressure of mines; and difficulties in controlling surface subsidence after mining. The E1302 working face of Shanxi Gaohe Energy was taken as the engineering background in the work. The mechanical properties of gangue paste-filling materials were studied through laboratory tests, and the critical conditions for bending and fracture of the coal seam roof were analyzed. Discrete-element numerical simulation software was used to study the fracturing process of the roof, and the reasonable filling rate to ensure roof stability was determined to be 95%. Meanwhile, overlying stratum movement and mine-pressure weakening law were studied through numerical simulations and field measurement. The results showed that fracture development during the mining process of thick-coal paste filling was divided into the advanced development, re-compaction, and steady-state maintenance of fractures. Fractures advanced in a “sail shape” and developed only in the main-roof rock strata after recompaction. The maximum subsidence angle of the working face was 87.13° after mining, with a subsidence factor of 0.034 and a maximum horizontal movement coefficient of 0.71. The advanced stress value was weakened by 40%, and the influenced area was reduced by 13%. Overlying stratum movement was controlled, and mine pressures were significantly weakened. The work can provide a scientific basis for green backfill mining, roadway support design, and backfill mining equipment selection. Full article
Show Figures

Figure 1

22 pages, 4729 KiB  
Review
Research Findings on the Application of the Arch Structure Model in Coal Mining, a Review
by Quansheng Li, Junting Guo, Cun Zhang, Yuliang Yang, Jianqi Ma and Zhaopeng Ren
Sustainability 2022, 14(22), 14714; https://doi.org/10.3390/su142214714 - 08 Nov 2022
Cited by 3 | Viewed by 1265
Abstract
Studying the movement law and failure mechanism of overburden is important to underground safety production, aquifer protection, surface subsidence and ecological protection. A commonly used model, the arch structure model, for studying overburden movement is systematically reviewed in this paper. First, the arch [...] Read more.
Studying the movement law and failure mechanism of overburden is important to underground safety production, aquifer protection, surface subsidence and ecological protection. A commonly used model, the arch structure model, for studying overburden movement is systematically reviewed in this paper. First, the arch structure in the mining field is divided into an unconsolidated layer arch, beam arch (hinged arch), and overburden arch according to arching medium. On this basis, the research progress and existing problems of these three arch structure models are discussed according to the research means, including theoretical modeling, numerical simulation, similar simulation, and field measurements. The application of the arch structure model focuses on the prediction and prevention of mining pressure and surface subsidence, and there are relatively few means to actively regulate overburden arch. Thus, three control methods of the arch structure in underground coal mining are proposed: the preset arch structure method before coal mining, process control arch methods during coal mining, and end reinforcement control arch methods after coal mining. Finally, the main research focus on the arch structure model in the future is discussed. Full article
Show Figures

Figure 1

19 pages, 5080 KiB  
Article
A Novel Analytical Model of Mining Subsidence Considering Time Effect Based on the Probability Integral Theory
by Peng Li, Yingchun Li, Qiang Li, Zhiguo Cao and Lujun Wang
Sustainability 2022, 14(21), 14443; https://doi.org/10.3390/su142114443 - 03 Nov 2022
Viewed by 1106
Abstract
Surface subsidence caused by underground coal mining has received wide attention due to its impact on the ecological environment. To obtain first-hand data on mining subsidence, we arranged line measurement stations in the mining area of the Weiqiang coalfield and implemented surface movement [...] Read more.
Surface subsidence caused by underground coal mining has received wide attention due to its impact on the ecological environment. To obtain first-hand data on mining subsidence, we arranged line measurement stations in the mining area of the Weiqiang coalfield and implemented surface movement observation at its first mining working face and obtained the dynamic subsidence curve. The subsidence curves reflected the initial, active and declining stages of subsidence at each measurement point at a basic level, and were consistent with the general rule of surface subsidence. To accurately analyze the surface movement caused by coal mining, based on the probability integral method and considering the actual advancement progress of the working face, a new three-dimensional dynamic prediction model, namely the strip unit mining model, was proposed. The core assumption of this model was that the longwall mining is regarded as the result of superposition of many units of mining. Considering the influence of different mining times and periods after mining, the subsidence time function of two-time factors was introduced into the strip unit mining model, and the final formulation of the dynamic subsidence prediction of the three-dimensional surface is derived by considering the time factor. Based on the analysis of the measured data of the Weiqiang coalfield, the prediction parameters of surface movement were obtained, and the surface movement and deformation are predicted via the probability integral method. Finally, the measured surface subsidence was compared with the theoretically-predicted one. The good match showed that the parameters of the probability integral method, determined according to the measured data, meet the requirements of geological conditions and mining settings in the mining area, and the predicted subsidence curves agreed well with the field measurements, demonstrating the effectiveness of the newly-developed strip unit mining model. Full article
Show Figures

Figure 1

14 pages, 1889 KiB  
Article
Ethical Construction and Development of Mining Engineering Based on the Safe, Efficient, Green, and Low-Carbon Concept
by Fangtian Wang, Hongfei Qu, Wei Tian, Shilei Zhai and Liqiang Ma
Sustainability 2022, 14(21), 13811; https://doi.org/10.3390/su142113811 - 25 Oct 2022
Cited by 2 | Viewed by 3661
Abstract
Modern mining engineering has become a huge system project with the increased intensification and complexity of mining engineering, which interwinds, involving many factors. Ethical issues in the main body of mining engineering have become more and more prominent. What must complement ongoing discussions [...] Read more.
Modern mining engineering has become a huge system project with the increased intensification and complexity of mining engineering, which interwinds, involving many factors. Ethical issues in the main body of mining engineering have become more and more prominent. What must complement ongoing discussions is a more professional and systematic analysis that engages with mining engineering on the socio-technical systems. In this paper, first, the connotation and basic principles of mining engineering ethics are put forward. Then, the ethical responsibilities that mining engineers may face are analyzed. It is suggested that the code of mining engineering ethics can, in practice, provide engineers with the necessary guidelines to avoid mine accidents caused by wrong decisions. In addition, a case base is introduced to train students to analyze engineering ethics in practical cases, and four typical case studies are discussed in detail. Then, the implementation paths of mining engineering ethics are studied, which are centered on the concept of safe, efficient, green, and low-carbon development. Finally, we suggest that improving the ethical norms of mining engineering, personnel training system, and moral supervision of mining projects will enable engineers to deal with the ethical issues of mining engineering more effectively, thereby improving the sustainability of mining engineering. Full article
Show Figures

Figure 1

16 pages, 967 KiB  
Article
Impact of Changes in Membership on Prices of a Unified Carbon Market: Case Study of the European Union Emissions Trading System
by Yue Xu and Dayu Zhai
Sustainability 2022, 14(21), 13806; https://doi.org/10.3390/su142113806 - 25 Oct 2022
Cited by 3 | Viewed by 1510
Abstract
Using the event study methodology, the paper studies the effects of 22 key events in countries’ process of entering and exiting the European Union on returns of European Union Allowance (EUA) future prices in the EU Emissions Trading System (EU ETS). The events [...] Read more.
Using the event study methodology, the paper studies the effects of 22 key events in countries’ process of entering and exiting the European Union on returns of European Union Allowance (EUA) future prices in the EU Emissions Trading System (EU ETS). The events include 17 entry events concerning the signing of relevant agreements, becoming a candidate or potential candidate country, the process of a negotiation and formally entering the EU, and five exit events including the process of Brexit and the suspension of Iceland. The results show that two entry events involving Albania and Ukraine, respectively, have a significant positive impact, and five entry events have a significant negative impact. Among the exit events, the announcement of the Brexit referendum results causes significant negative market reaction. Most events regarding small carbon emitters entering the EU lead to negative cumulative abnormal returns (CAR) of EUA prices, and a significant negative correlation between the countries’ annual average carbon emissions and CAR is found, while the change of national allocation plans does not affect the market reaction notably. In the process of establishing a unified carbon market, regulators should carry out appropriate policy arrangements of emission allowances allocation when new members join, in order to guide market expectations and enhance market stability. Full article
Show Figures

Figure 1

15 pages, 9422 KiB  
Article
Characteristics of Strata Behavior and Differentiated Control of Fully Mechanized Mining Working Face with Abnormal Roof
by Qiang Fu, Ke Yang, Xiang He, Zhen Wei and Qinggan Yang
Sustainability 2022, 14(20), 13354; https://doi.org/10.3390/su142013354 - 17 Oct 2022
Cited by 2 | Viewed by 921
Abstract
The roof control of a fully mechanized mining face has a significant impact on coal extraction. Therefore, information about strata behavior and differentiated control measures for abnormal roofs are needed. In the present research, we used the ground pressure theory to calculate the [...] Read more.
The roof control of a fully mechanized mining face has a significant impact on coal extraction. Therefore, information about strata behavior and differentiated control measures for abnormal roofs are needed. In the present research, we used the ground pressure theory to calculate the interval of the first and periodic weighting of working faces 11113, 11213, and 11313 in the Panbei mine. The maximum support working resistance required by the three working faces was calculated considering the influence of the hard roof, fault zone, and skip mining mode on the relationship between support–surrounding rock. In addition, we determined the hydraulic support for the three working faces taking into account the impact of roof lithology on ground pressure, as well as the layout and mining sequence of the working face. In order to ensure the safety of the working face mining, we implemented the laying mesh method, controlling the roof, providing side protection in the fault-affected area, and using the violent ground pressure control method for advanced deep hole pre-split blasting under hard roof conditions. The engineering practice showed that the effective control of roof ground pressure in abnormal areas was achieved using these control measures. Full article
Show Figures

Figure 1

21 pages, 68775 KiB  
Article
Space-Time Evolution Characteristics of Deformation and Failure of Surrounding Rock in Deep Soft Rock Roadway
by Xinfeng Wang, Yiying Zhang, Qiao Zhang, Youyu Wei, Wengang Liu and Tian Jiang
Sustainability 2022, 14(19), 12587; https://doi.org/10.3390/su141912587 - 03 Oct 2022
Cited by 9 | Viewed by 1404
Abstract
In view of the problems of large deformation of surrounding rock, high in-situ stress, and serious soft fracture of rock stratum in deep soft rock roadway, the instability deformation failure mode of deep soft rock roadway is analyzed theoretically. The FLAC3D software [...] Read more.
In view of the problems of large deformation of surrounding rock, high in-situ stress, and serious soft fracture of rock stratum in deep soft rock roadway, the instability deformation failure mode of deep soft rock roadway is analyzed theoretically. The FLAC3D software is used to establish a three-dimensional numerical model of surrounding rock damage under load, and to study the displacement, stress, and plastic expansion process of damage and failure evolution in the surrounding rock of the roadway. The mechanical response mechanism of deep soft rock roadway surrounding rock bending deformation, elastoplastic transformation, and unloading failure is verified by MATLAB numerical analysis, and the space-time evolution characteristics of soft rock deformation and failure are revealed. The results show that the surrounding rock of deep soft rock roadway has many failure modes, such as obvious displacement and deformation, high stress concentration, and intensified plastic transformation in the surrounding rock. The vertical stress in the surrounding rock is concentrated at the direct top and bottom, and the horizontal stress is concentrated at the roadway side and bottom; plastic deformation and failure first appeared at the roadway side, and then extended to other parts. The research conclusion provides an important reference for surrounding rock control and roof management of high-stress soft rock roadway under deep excavation disturbance. Full article
Show Figures

Figure 1

18 pages, 6978 KiB  
Article
Experimental Study of Confined-Pressure Soaking on Sandstone Damage-Fracture Characteristics Using Acoustic Emission and Energy Dissipation
by Baobao Chen, Lei Wang and Ming Zhang
Sustainability 2022, 14(19), 12381; https://doi.org/10.3390/su141912381 - 29 Sep 2022
Cited by 1 | Viewed by 999
Abstract
In order to explore the mechanical characteristics of confined-pressure soaking (CPS) sandstone during the damage-fracture process, the uniaxial compression and acoustic emission (AE) experiment of CPS sandstone was conducted. The mechanical parameters, fracture morphology, AE and energy characteristics under uniaxial stress were researched. [...] Read more.
In order to explore the mechanical characteristics of confined-pressure soaking (CPS) sandstone during the damage-fracture process, the uniaxial compression and acoustic emission (AE) experiment of CPS sandstone was conducted. The mechanical parameters, fracture morphology, AE and energy characteristics under uniaxial stress were researched. The results show that the uniaxial compressive strength and elastic modulus decrease as a logarithmic function with CPS parameters, corresponding to the inflection point of modification. The fracture mode gradually changes from brittleness to toughness with the increase in moisture content. The difference between fracture fragmentation and mechanical behavior mainly depends on the degree of CPS. The evolution of AE characteristics and energy dissipation has a good correspondence with CPS specimens. The higher the CPS degree is, the less the AE cumulative number is and the longer the excitation time is. Based on the phase variation of AE events and energy dissipation, the CPS damage variables are proposed to quantify the weakening degree and reveal the damage evolution process. The results provide a useful foundation for evaluating rock failure and improving service life. Full article
Show Figures

Figure 1

12 pages, 5447 KiB  
Article
Soil Reinforcement with Geocells and Vegetation for Ecological Mitigation of Shallow Slope Failure
by Gaofeng Song, Xiaoruan Song, Shiqin He, Dezhong Kong and Shuai Zhang
Sustainability 2022, 14(19), 11911; https://doi.org/10.3390/su141911911 - 21 Sep 2022
Cited by 3 | Viewed by 1653
Abstract
Soil reinforcement using geocells and vegetation is one of the best forms of soil protection for shallow slope failure control. The geocell supports the vegetation growth and the vegetation cover provides protection against the surface erosion. This work proposed a soil treatment method [...] Read more.
Soil reinforcement using geocells and vegetation is one of the best forms of soil protection for shallow slope failure control. The geocell supports the vegetation growth and the vegetation cover provides protection against the surface erosion. This work proposed a soil treatment method using geocells for supporting the vegetation growth and stabilizing the shallow slope. A step-by-step installation of the geocells in the field and the development of vegetation growth were also described. The authors developed nine physical models that were reinforced with different sized geocell structures (no reinforcement and small and large geocell reinforcement). The models were placed under three rainfall intensities (50, 75, and 100 mm/h). The stability of the slope under the rainfall and the performance of the geocell reinforcement were assessed from the the development of slope failures, the soil erosion and the slope displacement. The results showed that the stability of geocell reinforced slopes were better off than the unsupported slope. The small geocell-reinforced slopes showed less measured soil erosion and also smaller slope displacement. In general, small geocells outperformed large geocells in terms of the erosion control and slope stabilization. The rainfall intensity dramatically increased the soil erosion on slopes. The geocell- and vegetation-treated slope in the field showed good resistance against the surface erosion. Full article
Show Figures

Figure 1

24 pages, 29068 KiB  
Article
Spatial Pattern Reconstruction of Water and Land Resources in Coal Mining Subsidence Areas within Urban Regions
by Xiaojun Zhu, Feng Zha, Hua Cheng, Liugen Zheng, Hui Liu, Wenshan Huang, Yu Yan, Liangjun Dai, Shenzhu Fang and Xiaoyu Yang
Sustainability 2022, 14(18), 11397; https://doi.org/10.3390/su141811397 - 11 Sep 2022
Viewed by 1648
Abstract
Water and land resources are important material bases of economic and social development, and their spatial patterns determine the pattern of the urban development. The development and expansion of coal-resource-based cities have introduced new societal problems, such as the overlapping of new city [...] Read more.
Water and land resources are important material bases of economic and social development, and their spatial patterns determine the pattern of the urban development. The development and expansion of coal-resource-based cities have introduced new societal problems, such as the overlapping of new city construction areas and underground coal resources. Underground coal mining also leads to surface subsidence, which destroys water and land resources and seriously affects the sustainable development of coal-resource-based cities. The surface subsidence area takes a long time to stabilize, and may form a large waterlogging area due to the high groundwater level, thereby increasing the difficulty of reconstructing mining subsidence areas. In this context, a scientific and complete method for reconstructing the spatial pattern of water and land resources in unstable coal mining subsidence areas within urban is proposed in this paper. This method initially predicts the surface subsidence value and then divides the subsidence area within the urban region into the waterlogging area and the non-waterlogging area according to the surface subsidence value. The waterlogging area will be renovated into a landscape lake district in the city by a series of transformation measures. Afterwards, goaf rock mass activation and surface stability evaluation analyses are performed in the non-waterlogging area. According to the evaluation results, land resources can be divided into unaffected, restricted and prohibited building areas, with each area being transformed differently. The Lv Jin Lake in Huaibei is selected as a case study, and the proposed method is applied to reconstruct its water and land resources. The original spatial pattern of the large-scale waterlogging area and abandoned land due to mining subsidence in urban areas is then reconstructed into a spatial pattern that integrates the urban landscape, scenario living and eco-tourism. Compared with traditional subsidence area management, the proposed method greatly increases the utilization value of water and land resources, improves the urban ecological environment, enhances the urban quality and effectively alleviates the problems of land shortage and human–land conflict in coal-resource-based cities. Full article
Show Figures

Figure 1

17 pages, 7228 KiB  
Article
Comprehensive Water Inrush Risk Assessment Method for Coal Seam Roof
by Zhenming Sun, Wenpeng Bao and Mei Li
Sustainability 2022, 14(17), 10475; https://doi.org/10.3390/su141710475 - 23 Aug 2022
Cited by 7 | Viewed by 1327
Abstract
In order to prevent coal mine water inrush accidents, it is necessary to appropriately assess the water abundance of coal mines based on drilling and geophysical data. This paper studied a comprehensive risk assessment method of water inrush. First, a water inrush risk [...] Read more.
In order to prevent coal mine water inrush accidents, it is necessary to appropriately assess the water abundance of coal mines based on drilling and geophysical data. This paper studied a comprehensive risk assessment method of water inrush. First, a water inrush risk index was proposed based on the analytic hierarchy process-entropy method (AHP-EM) and the water-rich structure index was proposed based on the geological data coupled calculation, then weighted two indices above which established the comprehensive water inrush risk assessment method. Secondly, eight factors were chosen as risk control factors of water inrush: core recovery, aquifer thickness, distance from the indirect aquifer to the coal seam, aquiclude thickness, height of water-conducting fracture zone, sand-mud ratio, total layers of aquifer and aquiclude, and the equivalent thickness of sandstone. Finally, the No. 2 coal seam of Dahaize coal mine was taken as the research object, the factors were calculated, and a comprehensive water inrush assessment model was constructed. With site investigation and observation, the water inrush risk assessment model of the No.2 coal seam roof is consistent with the actual mining situation, which verifies the validity of the model. In addition, this method was used to evaluate the water-richness of the weathered bedrock fractured aquifer in the Zhangjiamao coal mine. The practical application of the two mines has verified the generality of the approach. The research could provide scientific assistance for mine water hazard mitigation and mining safety. Full article
Show Figures

Figure 1

22 pages, 9616 KiB  
Article
Research on the Development Law of Pre-Mining Microseisms and Risk Assessment of Floor Water Inrush: A Case Study of the Wutongzhuang Coal Mine in China
by Lei Huang, Yanchun Xu, Shiqi Liu, Qiukai Gai, Wei Miao, Yubao Li and Lisong Zhao
Sustainability 2022, 14(15), 9774; https://doi.org/10.3390/su14159774 - 08 Aug 2022
Cited by 2 | Viewed by 1579
Abstract
Coal-mining areas are widely distributed in Northern China, but are under threat from confined water in the mining operation, resulting in a series of floor water- inrush hazards. Therefore, it is significant to effectively evaluate the floor water inrush to ensure safe and [...] Read more.
Coal-mining areas are widely distributed in Northern China, but are under threat from confined water in the mining operation, resulting in a series of floor water- inrush hazards. Therefore, it is significant to effectively evaluate the floor water inrush to ensure safe and efficient coal mining. The 182602 working face of the Wutongzhuang coal mine served as the background for our research. The concept of “pre-mining microseisms” was proposed, and based on this, microseismic monitoring equipment was arranged on site. The correlation between microseismic events and the water abundance of an aquifer was analyzed, and a floor water inrush evaluation method was constructed based on the three elements of an aquifer and pre-mining microseisms. The main results are as follows: first, the microseismic events were excited by artificial disturbances before the mining of the working face including slurry diffusion and neighboring mining, which had the characteristics of sporadicity, clustering, and periodicity. Second, the regional distribution of water abundance was determined by taking the water inflow, water pressure, and grouting volume as the outward performance characteristics of water abundance in the Shanvuqing aquifer. Furthermore, the correlation coefficient between the pre-mining microseisms and the three elements of the aquifer (water inflow, water pressure, and grouting volume) was larger than 0.7. On this basis, an evaluation method associated with the water inrush risk along the strike of the working face was established based on pre-mining microseisms, dividing the working face into dangerous zones, suspected dangerous zones, and safe zones. Furthermore, pre-mining microseisms, water abundance, and structures were introduced as risk-evaluation indices, and the complete weight was calculated using an analytic hierarchy process and entropy-weight technique, before a vulnerability index model of floor water inrush was built. Finally, targeted treatment procedures were efficiently implemented to ensure the safe mining of working face 182602 due to the successful prediction of potential water risk zones. The research results provide scientific and technological support for pre-mining microseisms combined with water abundance as a technical method to prevent floor water inrush. Full article
Show Figures

Figure 1

18 pages, 7855 KiB  
Article
Study on Shape Characteristics of Plastic Zone in Heterogeneous Roadway-Surrounding Rock
by Jun Li, Zheng Wu, Wenlong Zhang, Nianjie Ma and Shuying Guo
Sustainability 2022, 14(15), 9480; https://doi.org/10.3390/su14159480 - 02 Aug 2022
Cited by 1 | Viewed by 1172
Abstract
Aiming at the surrounding rock failure of heterogeneous and unequal pressure circular roadways, the approximate analytical algorithm of the plastic zone is proposed. Through the comparison of analytical calculations and numerical simulation, the shape characteristics and evolution law of the surrounding rock’s plastic [...] Read more.
Aiming at the surrounding rock failure of heterogeneous and unequal pressure circular roadways, the approximate analytical algorithm of the plastic zone is proposed. Through the comparison of analytical calculations and numerical simulation, the shape characteristics and evolution law of the surrounding rock’s plastic zone are studied, and the relative error of the two calculation methods is analyzed. The results show the following: (1) With an increase or decrease in the lateral pressure coefficient, the shape of the plastic zone of the roadway-surrounding rock presents a circular-ellipse-butterfly shape change law, and the outer edge of the plastic zone presents a scattered shape, without a continuous boundary. (2) In the butterfly-shaped plastic zone, the butterfly leaf always lies between the maximum confining pressure and the minimum confining pressure and rotates with the pressure. (3) There is a certain amount of error between the maximum value of the plastic zone solved by an analytical algorithm and numerical simulation, and the relative error is positively related to the burial depth and lateral pressure coefficient of the roadway and negatively related to the strength of the surrounding rock. (4) In addition, the relative error of the plastic zone calculation of the multi-layer heterogeneous combination roadway is larger than that of the single heterogeneous roadway. Full article
Show Figures

Figure 1

23 pages, 9323 KiB  
Article
Mining Subsidence Prediction Model and Parameters Inversion in Mountainous Areas
by Bang Zhou, Yueguan Yan, Huayang Dai, Jianrong Kang, Xinyu Xie and Zhimiao Pei
Sustainability 2022, 14(15), 9445; https://doi.org/10.3390/su14159445 - 01 Aug 2022
Cited by 3 | Viewed by 1473
Abstract
Coal mining in mountainous areas is general in China, especially in Shanxi Province. Under the influence of topography in mountainous areas, surface collapses and landslides caused by underground mining happen at a certain frequency and threaten human lives and assets. Accurate prediction of [...] Read more.
Coal mining in mountainous areas is general in China, especially in Shanxi Province. Under the influence of topography in mountainous areas, surface collapses and landslides caused by underground mining happen at a certain frequency and threaten human lives and assets. Accurate prediction of the movement and deformation of mining subsidence in mountainous areas facilitates the prevention and control of geological disasters. The probability integral method is an official prediction method for mining subsidence prediction in China, while it is lacking in the prediction accuracy in mountainous areas due to the inherent topography. Therefore, a practical prediction model based on slopes slip combined parameters optimization was proposed in this study. The slip subsidence and slip horizontal movement were deduced based on the probability integral method considering the topography (slope angle α < 30°) and geological conditions (loess covered) to build the prediction model. The dynamic step fruit fly optimization algorithm (DSFOA) was applied for parameters inversion about the probability integral method in the proposed prediction model, while the other parameters in the proposed model were determined by mechanics analysis based on the nature of losses. The determination of parameters is more efficient, objective and reasonable, so that the prediction accuracy can be improved. The measured data of the working panel 22,101 located in Taiyuan, Shanxi Province was verified by this practical model, and the result shows that the mean square error of subsidence and the horizontal movement was decreased to 71 mm and 276 mm, respectively, hence, the applicability of the proposed mining subsidence prediction model in mountainous areas is verified. This work will contribute to a comprehensive understanding on the law of surface movement and provide theoretical guidance for surface damage prevention and control in mountainous mining areas. Full article
Show Figures

Figure 1

16 pages, 6514 KiB  
Article
The Optimization of Coal Pillars on Return Air Sides and the Reasonable Horizon Layout of Roadway Groups in Highly Gassy Mines
by Qi Ma, Yidong Zhang, Linsheng Gao, Zexin Li, Guangyuan Song and Yu Zheng
Sustainability 2022, 14(15), 9417; https://doi.org/10.3390/su14159417 - 01 Aug 2022
Cited by 4 | Viewed by 1043
Abstract
Multiple roadways are opened to solve the difficulties in gas control in the high seam working face of high gassy mines, resulting in a large width of coal pillars between roadway groups. Moreover, recovering coal pillars is challenging during stoping, which causes serious [...] Read more.
Multiple roadways are opened to solve the difficulties in gas control in the high seam working face of high gassy mines, resulting in a large width of coal pillars between roadway groups. Moreover, recovering coal pillars is challenging during stoping, which causes serious resource waste. While the size of coal pillars is optimized, the reasonable horizon layout of roadway groups is performed to ensure a fine recovery rate of coal resources, mine safety, and efficient production. Theoretical analysis was applied to calculate the stress distribution of surrounding rocks around coal pillars based on the engineering practice of the W2302 working face in the Sihe Coal Mine. The MathCAD software Prime 2.0 combined with the on-site measured stress was used to draw the stress distribution under different coal pillar widths, which can derive the stress distribution data of the floor. The vertical stress concentration factors tended to be consistent at 10 m below the coal pillars and about 12 m from the centerline of coal pillars under different coal pillar widths, this area was suitable for the layout of floor rock roadways with a stress concentration factor of about 1. Numerical simulations were used to compare the stress distributions of the roadway floor and the deformation features of surrounding rocks under different coal pillar widths. The coal pillar width was finally determined to be 45 m, which optimized the size of coal pillars. The return air roadways were arranged at 9.8 m below the coal seam combined with the strata distribution on-site. According to the industrial test on-site, the return air roadways were available during the service period, which showed reliable theoretical analysis and simulation results. A reasonable horizon layout of return air roadways can provide a scientific basis and reference for similar projects. Full article
Show Figures

Figure 1

15 pages, 7462 KiB  
Article
Study on the Optimization of Proportion of Fly Ash-Based Solid Waste Filling Material with Low Cost and High Reliability
by Denghong Chen, Tianwei Cao, Ke Yang, Ran Chen, Chao Li and Ruxiang Qin
Sustainability 2022, 14(14), 8530; https://doi.org/10.3390/su14148530 - 12 Jul 2022
Cited by 2 | Viewed by 1137
Abstract
In order to solve the problem of the high cost of coal-based solid waste bulk stacking and paste filling in the large-scale coal electrification base in East NingXia, in this study, fly ash is skillfully used to replace the broken coal gangue as [...] Read more.
In order to solve the problem of the high cost of coal-based solid waste bulk stacking and paste filling in the large-scale coal electrification base in East NingXia, in this study, fly ash is skillfully used to replace the broken coal gangue as the mixed filling material. As using a jaw crusher for crushing large coal gangue is expensive, and its energy consumption is relatively high, paste filler using fly ash as aggregate is studied through micro and macro test analyses. Using response surface methodology design software, 29 groups of mix proportion schemes are designed to obtain the best mix proportion. In addition, the radar results of slump, slump flow, and comprehensive strength are obtained by the normalization method. According to the radar chart results of the three normalized indexes, the optimal ratio parameters are as follows: the fly ash in solid phase is 79%, the mass of fly ash to the mass of cement (FA/C) is 6:1, the solid mass concentration is 78%, the fly ash to gasification slag is 1:1, and the results show that σ3d = 2.20 MPa, slump = 205 mm, and flow = 199 mm. Taking the solid mass concentration, FA/C, the fly ash content in solid phase, and the coal gangue-to-gasification slag ratio as independent variables, the influence of single-factor and multi-factor interactions of the independent variables are analyzed based on the response surface model. It is found that the solid mass concentration and FA/C have a very significant effect on the early strength. Replacing coal gangue base with fly ash base can effectively reduce the crushing cost and energy consumption and provide low-cost and highly reliable technical reserves for large-scale filling. Full article
Show Figures

Figure 1

15 pages, 7440 KiB  
Article
Determination of Fractured Water-Conducting Zone Height Based on Microseismic Monitoring: A Case Study in Weiqiang Coalmine, Shaanxi, China
by Wei Gao, Yingchun Li and Qingyuan He
Sustainability 2022, 14(14), 8385; https://doi.org/10.3390/su14148385 - 08 Jul 2022
Cited by 4 | Viewed by 1147
Abstract
The NO. 3 coal seam of the Weiqiang coalmine is faced with a water inrush threat caused by two large reservoirs and the upper confined aquifer. However, existing empirical formulas cannot accurately predict the height of the fractured water-conducting zone; thus, it is [...] Read more.
The NO. 3 coal seam of the Weiqiang coalmine is faced with a water inrush threat caused by two large reservoirs and the upper confined aquifer. However, existing empirical formulas cannot accurately predict the height of the fractured water-conducting zone; thus, it is necessary to investigate the extent of the fractured water-conducting zone according to the geological conditions of the No. 3 coal seam. The microseismic monitoring system (MMS) was used to monitor the surrounding area of the 1311 working face in real time to obtain the microseismic event information during the fracture development. The detailed situation of the fractured water-conducting zone in three-dimensional space was determined by computer analysis. The results show that the height of the fractured water-conducting zone is 110 m, which is consistent with the range (105.4~120.4 m) measured by various field drilling results and the mechanical mechanism analysis based on the key strata theory (112 m). The achievement of microseismic monitoring provides a guarantee for safety production and prevention and control of mine water disaster in the 1311 working face of the No. 3 coal seam, and can also be applied and promoted in coalmines with similar geological conditions, with significant social and economic benefits. Full article
Show Figures

Figure 1

24 pages, 8414 KiB  
Article
Quantitative Study on the Law of Surface Subsidence Zoning in Steeply Inclined Extra-Thick Coal Seam Mining
by Yueguan Yan, Yanjun Zhang, Yuanhao Zhu, Jinchi Cai and Junyao Wang
Sustainability 2022, 14(11), 6758; https://doi.org/10.3390/su14116758 - 31 May 2022
Cited by 2 | Viewed by 1342
Abstract
The damage of overlying strata and ground surface caused by the one-time mining space is relatively severe in steeply inclined extra-thick coal seams. The unique law of surface subsidence at these conditions is still missing. Taking Huating Dongxia Coal Mine as the research [...] Read more.
The damage of overlying strata and ground surface caused by the one-time mining space is relatively severe in steeply inclined extra-thick coal seams. The unique law of surface subsidence at these conditions is still missing. Taking Huating Dongxia Coal Mine as the research background, this paper reveals the law-governing effects on rock strata and surface movement and deformation caused by steeply inclined extra-thick coal seam mining with different coal seam dip angles and coal thicknesses by using the methods of surface measurement, theoretical analysis, and numerical simulation. Based on the characteristics of the surface inclination deformation, the surface is divided into four areas along the tendency section line—namely, an outcrop discontinuous deformation area, an overall subsidence area, a gradual subsidence area, and a slight subsidence area. The results show that the influence of the coal seam dip angle on surface subsidence zoning in steeply inclined and thick coal seams is mainly reflected in the affected area range and the form of damage. Coal thickness has a weak effect on the form of rock strata damage and surface movement. Utilizing the influence of the coal seam dip angle and coal seam thickness on the change in the surface subsidence zoning, the calculation formulas for each area range and zoning angle in relation to the coal seam dip angle, coal thickness, mining depth, and vertical stage height are established. The research results can provide a reference to evaluate the influence of mining, especially in steeply inclined extra-thick coal seams. Full article
Show Figures

Figure 1

18 pages, 8417 KiB  
Article
Research on Mechanical Behavior and Energy Evolution of Coal and Rocks with Different Thin Spray-On Liners Thickness under Uniaxial Compressive Loading
by Yixin Zhao, Xiang Fu, Yangyang Shi, Bowen Zhao, Xingyu Fu, Xiufeng Zhang and Yang Chen
Sustainability 2022, 14(10), 5909; https://doi.org/10.3390/su14105909 - 13 May 2022
Viewed by 1273
Abstract
Compared with the traditional supporting materials such as the bolts, mesh, and concrete, thin spray-on liners (TSLs) have the advantages of improving impact energy bearing and absorption capacity of rocks. In this study, the uniaxial compressive mechanical response feature of white sandstone, yellow [...] Read more.
Compared with the traditional supporting materials such as the bolts, mesh, and concrete, thin spray-on liners (TSLs) have the advantages of improving impact energy bearing and absorption capacity of rocks. In this study, the uniaxial compressive mechanical response feature of white sandstone, yellow sandstone, and coal with different coating thickness of TSLs were investigated through laboratory tests and theoretical analysis. The hard segments and soft segments of TSLs induced microphase separation, and formed the physical cross-linking. The hard segment evenly dispersed in the soft segment, which improved the mechanical strength of the TSLs. The confining pressure was affected by the TSL-coated coal and rocks, which improved the mechanical strength of the rocks and coal under UCS loading. It was discovered that the uniaxial compressive strength (UCS) increases with an increase in the TSL coating thickness, and UCS increments of the coated white sandstone, yellow sandstone and coal were 4.6%, 25.51%, and 43.75%, respectively. The energy absorption capacities of the coated coal, and yellow and white sandstones gradually decreased with an increase in their TSLs coating thickness. Meanwhile, the energy-absorbing capacity of a coated rock reduced gradually as rock coating decreases. Furthermore, the energy-absorbing capacity of coal is greater than that of yellow sandstone or white sandstone. By increasing the coating thickness, the total and dissipative energies in the yellow sandstone, white sandstone, and coal specimens were gradually increased, and energy increment was significantly more in coal (2–3 times), while the elastic energy remained nearly unchanged. Full article
Show Figures

Figure 1

14 pages, 3118 KiB  
Article
The Principle and Practice of Strong Mine Pressure Control in the Initial Mining and Caving Stages under Multiple Key Strata
by Kaijun Miao, Dapeng Wang, Shihao Tu, Hongsheng Tu, Defu Zhu, Xuewen Liu, Wenlong Li and Long Tang
Sustainability 2022, 14(10), 5772; https://doi.org/10.3390/su14105772 - 10 May 2022
Cited by 5 | Viewed by 1249
Abstract
The mechanism of strong mine pressure control in the initial mining and caving stages under multiple key strata (MKS) was studied by theoretical analysis, numerical simulation and field measurement in order to avoid the dynamic pressure accidents caused by the MKS breaking in [...] Read more.
The mechanism of strong mine pressure control in the initial mining and caving stages under multiple key strata (MKS) was studied by theoretical analysis, numerical simulation and field measurement in order to avoid the dynamic pressure accidents caused by the MKS breaking in interactions in the initial mining and caving stage. Panel 13103 (P13103) in the Shan Xi Jinshen Shaping Coal Mine was used sas the study site. The overlying structure and the breaking characteristics of the key strata were analyzed and the overlying structure model of longwall top-coal caving (LTC) under MKS was established. Reasonable initial mining heights and initial caving positions were determined and the spatial and temporal characteristics of ground pressure and roof structure of the working face in the mining process were obtained. The results show that, in the scheme of starting top-coal caving after the working face advanced 20 m, the support damage ratios were all greater than 50% with roof weighting, which is prone to induce prop crash accidents. The dynamic load formed by the second weighting was greater than first weighting under the MKS. The duration of mine pressure tended to be stable with fully developed caving zone heights. With the designed mining scheme, the safe and efficient mining of P13103 is guaranteed. Full article
Show Figures

Figure 1

21 pages, 6261 KiB  
Article
Research of Surrounding Rock Control of Gob-Side Entry Retaining Based on Deviatoric Stress Distribution Characteristics
by Zhiqiang Wang, Jiao Zhang, Jingkai Li, Peng Wang, Chao Wu and Lei Shi
Sustainability 2022, 14(9), 5660; https://doi.org/10.3390/su14095660 - 07 May 2022
Cited by 6 | Viewed by 1182
Abstract
In view of the difficulty of the surrounding rock control of retaining a roadway along a goaf, this paper takes the 5504 working face of the Hongshuliang Coal Mine as the engineering context. The uniaxial compressive strength and tensile strength of concrete filling [...] Read more.
In view of the difficulty of the surrounding rock control of retaining a roadway along a goaf, this paper takes the 5504 working face of the Hongshuliang Coal Mine as the engineering context. The uniaxial compressive strength and tensile strength of concrete filling material in the retained roadway are determined by laboratory tests. Through theoretical analysis, field investigation, numerical simulation and field measurement, the distribution characteristics of deviatoric stress and damage zone of the roadway surrounding rock in the mining process of the 5504 working face are studied here. Based on the failure of rock mass element caused by deviatoric stress tensors, the study shows that the thickness of the concrete wall is 2.2 m and the compressive strength of the concrete wall can reach 10.87~11.64 MPa in 3 days to 4 days, which can meet the support strength of the retained roadway. From the position of 90 m in front of the working face to the position of 100 m behind the working face, the distribution form of the roadway surrounding rock deviatoric stress is: symmetrical butterfly shape → single butterfly shape → narrow oblique strip → oblique 8 shape → wide oblique strip shape. When the distance between the retained roadway and the working face is 49 m, the retained roadway tends to be stable. Based on the distribution characteristics of the deviatoric stress outline line and the damage zone outline line of the retained roadway surrounding rock, the retained roadway surrounding rock is divided into three regions, and the combined support technology of “bolt + anchor cable + single pillar + reinforcement combined with steel plate to strengthen concrete wall” is proposed. Through field engineering practice, the maximum displacement of roof, floor, solid coal side and concrete wall side in the retained roadway is 136.6 mm, 78.8 mm, 62.3 mm and 43.3 m, respectively, and the surrounding rock control effect of the retained roadway is good. Full article
Show Figures

Figure 1

13 pages, 3309 KiB  
Article
The Method of Determining Layer in Bottom Drainage Roadway Taking Account of the Influence of Drilling Angle on Gas Extraction Effect
by Yuliang Yang, Penghua Han, Zhining Zhao and Wei Chen
Sustainability 2022, 14(9), 5449; https://doi.org/10.3390/su14095449 - 30 Apr 2022
Cited by 3 | Viewed by 1242
Abstract
The pre-drainage of coalbed methane through boreholes in the bottom drainage roadway (BDR) is the key measure to prevent and control coal and gas outburst. Different arrangement layers in the BDR will make a difference in the range of drilling angle and affect [...] Read more.
The pre-drainage of coalbed methane through boreholes in the bottom drainage roadway (BDR) is the key measure to prevent and control coal and gas outburst. Different arrangement layers in the BDR will make a difference in the range of drilling angle and affect the gas extraction effect. In this paper, the mathematical model of the rock loose circle area around elliptical drilling was constructed. Meanwhile, the fluid–solid coupling model is constructed by using COMSOL software, the dynamic response of coal permeability and volumetric strain with gas pressure and the Klinkenberg effect of gas are considered, and the effect of the change of the elliptical drilling angle on the pressure relief effect of the coal seam is studied. The results showed that the distance between the layer in the BDR and the pre-drainage coal seam would decrease, and the effective extraction length at the same point of gas extraction in the coal seam increases. The area of the rock loose circle and permeability around the drilling decayed negatively and exponentially with the increase in drilling angle. As the drilling angle decreased, the stress in the major axis of the ellipse at the drilling cross-section increased, so the drilling was prone to collapse, and the gas extraction was hindered. Finally, an optimal method of determining the layer in the BDR under the coupling effect of multiple factors was established by combining the measured ground stress. Through field measurement, the drilling extraction rate of the optimized scheme is 60% higher than that of the original scheme. Full article
Show Figures

Figure 1

18 pages, 66841 KiB  
Article
Research on the Optimization of Cutting Path of Cantilever Roadheader in Large Section Excavation
by Chengjun Hu, Yong Zhang, Rui Yu, Xinqiu Fang, Ziyue Xu, Lixin Wang and Baofu Zhao
Sustainability 2022, 14(9), 5345; https://doi.org/10.3390/su14095345 - 28 Apr 2022
Cited by 3 | Viewed by 1362
Abstract
Coal is an important resource for China and even for the whole world. With the improvement of mechanization, automation and intelligence of coal mining equipment in China, there has been an imbalance between the speed of mining and of excavating. Adopting efficient cutting [...] Read more.
Coal is an important resource for China and even for the whole world. With the improvement of mechanization, automation and intelligence of coal mining equipment in China, there has been an imbalance between the speed of mining and of excavating. Adopting efficient cutting paths is beneficial to improving roadway excavation efficiency and alleviating the imbalance between mining and excavation. In this paper, taking the 12307 belt roadway of Wangjialing Coal Mine as the research background, the geomechanical parameters and distribution characteristics of the surrounding rock were observed and studied, and the test results of in-situ stress, surrounding rock structure and surrounding rock strength were obtained. Based on the test results, a numerical model was established, and the stress and displacement distribution law of the surrounding rock of the roadway under different cutting paths were analyzed, and two optimal cutting paths were proposed based on the actual situation, and industrial tests were carried out. The test results show that using the “snake” cutting path from bottom to top, the roadway section forming effect is good, and a single cycle excavation takes 34 min, which verified the effectiveness of the cutting path design. On the basis of specific engineering geological conditions, excavation equipment and technology, combined with experimental testing, numerical simulation and other methods, the roadway excavation cutting path can be optimized, and the research results can provide a reference for the design of cutting paths for coal mine excavation roadways with the same geological conditions. Full article
Show Figures

Figure 1

16 pages, 4580 KiB  
Article
The Spatial Evolution Law and Water Inrush Mechanism of Mining-Induced Overburden in Shallow and Short Coal Seam Group
by Weidong Pan, Peng Jiang, Boyang Li, Jianghua Li and Yinchao Yang
Sustainability 2022, 14(9), 5320; https://doi.org/10.3390/su14095320 - 28 Apr 2022
Cited by 3 | Viewed by 1153
Abstract
In order to grasp the overburden evolution law of the shallow and short coal seam group, based on the key bed theory, a mechanical analysis of the longitudinal expansion of mining-induced overburden fractures in the coal seam group was carried out, and the [...] Read more.
In order to grasp the overburden evolution law of the shallow and short coal seam group, based on the key bed theory, a mechanical analysis of the longitudinal expansion of mining-induced overburden fractures in the coal seam group was carried out, and the spatial evolution characteristics of mining-induced overburden fractures were simulated by the numerical simulation method. The results show that in the process of working face advancement, with the continuous instability and failure of the overburden, the size and shape of the fracture network are also changed. The repeated mining of the lower coal seam further causes the secondary activation of the upper overburden, which makes the roof fractures of the partially compacted goaf violently move again. The “channel source” and “space source” continue to carry out the process of “generation-expansion-compression-generation-expansion”, in combination with pore fracture elastic theory. The water inrush characteristics of the whole coal seam are divided into three “solid-liquid” coupling stages: the original gap seepage stage, the initial water discharge stage of mining fissures and the water inrush stage of fractured rock mass. The steady value of water inflow and its variation characteristics with time are predicted by using the formula of deep well flow in a confined aquifer. Full article
Show Figures

Figure 1

22 pages, 77009 KiB  
Article
Study on the Pressure Relief Mechanism and Engineering Application of Segmented Enlarged-Diameter Boreholes
by Shitan Gu, Changpeng Chen, Bangyou Jiang, Ke Ding and Huajian Xiao
Sustainability 2022, 14(9), 5234; https://doi.org/10.3390/su14095234 - 26 Apr 2022
Cited by 11 | Viewed by 1356
Abstract
Ensuring the stability of surrounding rock while conducting pressure relief is key to roadway stability control and preventing rock burst. In this paper, segmented enlarged-diameter borehole destressing technology is proposed. The stress distribution around the borehole is analysed based on the theory of [...] Read more.
Ensuring the stability of surrounding rock while conducting pressure relief is key to roadway stability control and preventing rock burst. In this paper, segmented enlarged-diameter borehole destressing technology is proposed. The stress distribution around the borehole is analysed based on the theory of elasto-plastic mechanics, and the mechanism of pressure relief for segmented enlarged-diameter boreholes is studied. Secondly, The effects of the diameter of enlarged-diameter section, length of the enlarged-diameter section, and borehole space on pressure relief and roadway deformation were investigated. Finally, the optimal drilling parameters for Tangkou coal mine 6307 working face are analysed. The key parameters of segmented enlarged-diameter borehole pressure relief technology for the 6307 working face were determined and applied in field practice. Field monitoring results showed that the accumulated energy can be effectively reduced using segmented enlarged-diameter pressure relief boreholes, effectively controlling roadway deformation and providing reference for rock burst prevention and roadway stability control. Full article
Show Figures

Figure 1

17 pages, 6902 KiB  
Article
Calculation of the Height of the Water-Conducting Fracture Zone Based on the Analysis of Critical Fracturing of Overlying Strata
by Yi Tan, Hao Cheng, Wenyu Lv, Weitao Yan, Wenbing Guo, Yujiang Zhang, Tingye Qi, Dawei Yin, Sijiang Wei, Jianji Ren and Yajun Xin
Sustainability 2022, 14(9), 5221; https://doi.org/10.3390/su14095221 - 26 Apr 2022
Cited by 4 | Viewed by 1120
Abstract
Accurate division of the water-conducting fracturing zone (WCFZ) in the mining overburden serves as an important basis to evaluate the stability of coal mining under water bodies. Research on the WCFZ is conducive to controlling surface subsidence and realizing safe coal mining under [...] Read more.
Accurate division of the water-conducting fracturing zone (WCFZ) in the mining overburden serves as an important basis to evaluate the stability of coal mining under water bodies. Research on the WCFZ is conducive to controlling surface subsidence and realizing safe coal mining under water. Traditionally, the WCFZ is generally determined by field observation (liquid leakage method, borehole television, etc.) or empirical formula. Although these methods boast high accuracy, they are time-consuming and laborious and have some problems such as weak pertinence and a large value range. In this study, a mechanical model under the critical breakage condition of hard and soft strata was established on the basis of the specific geological and mining information of a mine. Besides, the stability condition for the broken strata to form the “masonry beam” structure and the deflection-based bending deformation formula of hard and soft strata were deduced, and the method of calculating the height of WCFZ based on the analysis of critical fracturing of soft and hard strata (hereafter referred to as the CFSHS-based height calculation method) was proposed. Furthermore, with reference to the results of specific engineering tests, the height of the WCFZ in the working face 15,101 of coal mine XJ was analyzed by means of theoretical analysis, numerical simulation and engineering verification, which verifies the rationality and practicability of the CFSHS-based height calculation method. Full article
Show Figures

Figure 1

17 pages, 31050 KiB  
Article
Investigation on Characteristics and Prevention of Rockburst in a Deep Hard and Soft Compound Stratum Tunnel Excavated Using TBM
by Bangyou Jiang, Mingjun Ding, Wenshuai Li, Shitan Gu and Hongguang Ji
Sustainability 2022, 14(6), 3190; https://doi.org/10.3390/su14063190 - 08 Mar 2022
Cited by 4 | Viewed by 1430
Abstract
Rockburst disasters frequently occur in deep tunnels excavated by TBM (tunnel boring machine) under complex geological conditions in western China. Using FLAC3D, the characterization of a three-dimensional numerical model of a compound stratum tunnel excavated by TBM is conducted, based on a water [...] Read more.
Rockburst disasters frequently occur in deep tunnels excavated by TBM (tunnel boring machine) under complex geological conditions in western China. Using FLAC3D, the characterization of a three-dimensional numerical model of a compound stratum tunnel excavated by TBM is conducted, based on a water transport project in Shanxi Province. Then, the characteristics of rockburst in deep hard and soft compound stratum tunnels excavated by TBM are revealed, and the energy criteria of the rockburst considering the rock brittleness are proposed. In addition, the prevention and control method of drilling pressure relief for rockburst has been investigated. Results show that: (i) the rockburst risk of compound stratum tunnel excavated using TBM is mainly in the upper-hard rock part, while there is no rockburst risk in the soft rock part; (ii) after the excavation of the tunnel, slight rockburst risk occurs first in the hard rock area of the tunnel vault, and then the rockburst risk gradually rises to the strong level at 7 m behind the working face, indicating the hysteresis of strong rockburst; (iii) the rockburst in the vault of the rock surrounding the compound stratum tunnel has the effect of forming the deepest area, gradually narrowing to both sides, showing a “V” shape, and the occurrence of rockburst may not be completed at one time; (iiii) borehole pressure relief can significantly reduce the rockburst risk of surrounding rock in a tunnel. The larger the borehole diameter and depth, the better the effect of rockburst prevention. In addition, the effect of borehole diameter is more significant than depth. The research results provide guiding references for the prevention and control of similar rockburst disasters in underground engineering. Full article
Show Figures

Figure 1

14 pages, 2219 KiB  
Article
On-Site Measurement on Surface Disturbance Law of Repeated Mining with High Relief Terrain
by Weitao Yan, Junjie Chen, Wenfu Yang, Xiaosong Liu, Wenwen Wang and Wenkai Zhang
Sustainability 2022, 14(6), 3166; https://doi.org/10.3390/su14063166 - 08 Mar 2022
Cited by 7 | Viewed by 1431
Abstract
Underground coal mining in high relief terrain often causes problems such as ground collapse and mountain sliding. This produces disasters such as mountain collapse and landslides, which seriously endangers the ecological environment and human settlements in the coal mining area and causes a [...] Read more.
Underground coal mining in high relief terrain often causes problems such as ground collapse and mountain sliding. This produces disasters such as mountain collapse and landslides, which seriously endangers the ecological environment and human settlements in the coal mining area and causes a series of public security events. To improve and solve the related problems, it is necessary to master the impact law of underground mining on ground surface. Therefore, taking the working face 1310 of Jincheng coal industry as an example, this paper adopts a new and improved RTK measurement technology for field measurement and analyzes the surface disturbance law by using field data. The results show that under the action of repeated mining in high relief terrain areas, there is a sudden subsidence in the flat bottom area of the surface moving basin, the strike influence scope is small, the dip influence scope in the downhill direction is larger, the dip horizontal movement curve loses its antisymmetry, and the dip subsidence curve loses its left-right symmetry. Through the analysis, it is found that the high reverse slope weakens the original disturbance and reduces the influence range of surface mining. On the contrary, repeated mining enhances the original disturbance, expands the influence range of surface mining, and flattens the movement deformation curve. Research results can provide a technical reference for the formulation and implementation of environmental remediation and treatment technologies in mining areas under similar conditions. Full article
Show Figures

Figure 1

Back to TopTop