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Emergency management synergy capability is not only a "touchstone" to measure the operation effect of the emergency system of coal mine enterprises, it is an important symbol to reflect its level. In order to improve the level of emergency management in coal mines based on the PPRR theory of crisis management cycle, in this paper a hierarchical evaluation index system is constructed based on the emergency management process. A quantitative evaluation model of emergency synergy capacity is proposes based on the entropy–weighted elemental topology method to conduct evaluation and model validation for the case of J coal mine in Henan Province. The results show that the overall evaluation of the emergency management synergy capability of J Coal Mine is at a "good" level, with the emergency prevention synergy capability, emergency preparedness synergy capability, and recovery and reconstruction synergy capability at a "good" level and the emergency response synergy capability is at a "average" level. This indicates that the evaluation model is consistent with the current development of coal mining enterprises and has universal applicability. Therefore, this research can provide decision-making support for emergency management synergistic capacity building of coal mining enterprises to enhance the inherent driving force behind the early completion of the dual carbon task in the coal mining industry. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, the phase-out of coal from the energy structure has resulted in numerous old coal mines that possess abundant underground space resources suitable for underground pumped hydroelectric energy storage (UPHES). Site selection and estimation of potential are critical to the planning and implementation of UPHES in old coal mines. This paper introduces a two-step site selection concept, including a screening assessment followed by a comprehensive assessment, to determine suitable locations for UPHES. The screening indicators in the screening assessment comprise geological features, mine water disasters, and minimum installed capacity, while the analytic hierarchy process (AHP) is applied in the comprehensive assessment. Additionally, coal mines in Henan Province are preliminarily screened through the screening assessment and the potential for UPHES is thoroughly investigated. The estimated volume of the drifts and shafts in old coal mines is approximately 1.35 × 107 m3, while in producing coal mines, it is around 2.96 × 107 m3. Furthermore, the corresponding annual potential for UPHES is 1468.9 GWh and 3226.3 GWh, respectively. By consuming surplus wind and solar power, UPHES is able to reduce 4.68 × 105 tonnes of carbon dioxide (CO2) emissions. The study provides preliminary guidance for policy-makers in developing UPHES in old coal mines. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In deep mines, since the broken surrounding rocks & high-stress level of a roadway being near a coal seam, the creep characteristics of surrounding rocks should be considered as the main influencing factor in the selection for the roadway's location of the lower coal seam. Both VI15 and VI16-17 coal seams of the Pingdingshan No. 4 Coal Mine, in China, Henan province, are close coal seams with a depth of around 900 m. According to the traditional formula calculation results, when the lower coal seam roadway is staggered 10 m to the upper coal seam goaf, the roadway pressure behaviour is significant, and the support becomes difficult. In this paper, the properties of surrounding rock were tested and the influence of lower coal seam on the stress state of surrounding rock is analysed by numerical simulation, and systematic analysis on the stress and creep characteristics of the surrounding rock of the mining roadway and its effects on the deformation is performed. The results demonstrated that the roadway's locations in the lower coal seam can be initially divided into three zones: the zone with accelerated creep, the transition creep zone and the insignificant creep zone. The authors believed that the roadway layout in an insignificant creep zone can achieve a better supporting effect. Based on the geological conditions of the roadway 23070 of the VI16-17 coal seam of the Pingdingshan No. 4 Coal Mine, combined with the above analysis, a reasonable location of roadway (internal offset of 30 m) was determined using numerical simulation method. The reliability of the research results is verified by field measurement. The above results can provide a reference for selecting the roadway's location under similar conditions. [ABSTRACT FROM AUTHOR]

Clarifying the influencing factors of energy consumption in underground production processes of coal mine is the premise and foundation for the coal mining industry to control the energy consumption and intensity to achieve the goal of carbon peak and carbon neutrality. This paper aims to investigate and compare the differences in energy consumption and carbon emissions between a mining‐separating‐backfilling integrated coal mine (MSBICM) and a traditional coal mine and explore the effects of the main production links underground on carbon emission intensity in coal mines. Hence, taking an MSBICM in Henan province as an example, this study constructed an energy consumption and carbon emission model of the mine using system dynamics (SD) method. Based on this model, the energy consumption of the main production logistics system and auxiliary production system in MSBICM was simulated and analyzed. In addition, this study made a comparative analysis of the energy consumption of the different production links in the two types of coal mines. The results showed that: (1) the comprehensive mechanized coal mining with solid filling system and ventilation system were the subsystems with the highest and lowest energy consumption in MSBICM respectively. (2) The influence rates of raw coal mining, gangue filling, coal‐gangue separating, and material transportation on carbon emission intensity in coal mine were 1.09%, 1.34%, 1.09%, and 5.13%, respectively. (3) Under the same production and filling targets, energy consumption of underground transportation systems in MSBICM was found to be 336.66 tons of standard coal less than that in traditional coal mine. This study has helped clarify the complex relationships among the factors that influence energy consumption in coal mines and provided a reference for implementing dual control of energy consumption to promote low‐carbon mining of coal resources. [ABSTRACT FROM AUTHOR]

The accuracy of the drainage radius plays a vital role in the gas drainage effect, and the establishment of the drainage model and numerical calculation of the model has an essential value for the accurate determination of the drainage radius. Based on the elastoplastic constitutive model of mining coal and rock mass, effective stress equation, gas content equation, gas flow continuity, and control equation established by predecessors, the gas-solid coupling model of coal-rock deformation and pressure-relief gas flow in protective layer mining was established in this paper. The numerical simulation prototype was based on the mining engineering practice of a short-distance and underprotective steep seam mining in a mine in western Henan of China. COMSOL Multiphysics coupling software was used to numerically calculate the coupling model, and the influence radius of different mining pressure-relief area and different drainage time was obtained. The results show that under the same geological conditions and mining conditions, the impact range of drilling in the pressure-relief area of the protected layer is larger than that of the nonrelief area. As the working face of the protection layer advances, the pressure-relief area of the protected layer gradually increases, the influence range of the drainage borehole increases, the drainage borehole has undergone a process of initial stress-stress concentration-stress reduction-stress recovery successively, and the strike drainage radius is larger than the inclined. [ABSTRACT FROM AUTHOR]

Copyright of Mine Water & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Protective layer mining, as a dominating method for preventing coal and gas outburst, is generally adopted in highly gassy coal mines. In the absence of a suitable thickness coal seam to serve as the protective layer, the rock-coal composite protective layer was proposed in this paper. We conducted a series of simulations and engineering measurements to investigate the protective effect under the mining of the rock-coal composite protective layer of the Zhongtai coal mine located in the Hebi area of Henan, China. The numerical simulation analysis showed that, after the completion of protective layer mining, the minimum vertical stress of the No. 2-1 coal seam had been reduced to 3.46 MPa. The maximum vertical displacement of the No. 2-1 coal seam is 455.01 mm. The maximum expansion deformation of the No. 2-1 coal seam is 9.77‰; the effective pressure relief range is as long as 160 m. The similarity simulation experiment revealed that, after the completion of protective layer mining, the minimum vertical stress of the No. 2-1 coal seam is 4.0 MPa. The maximum vertical displacement of the No. 2-1 coal seam is 640 mm. The maximum expansion deformation of the No. 2-1 coal seam is 26.37‰; the effective protection range reaches 130 m. The engineering measurements demonstrated that the variation law of gas drainage parameters in the protected layer corresponds to the protected layer's vertical stress distribution law in numerical simulation and similarity simulation. With the exploitation of the composite protective layer, the protective layer's pressure begins to release. The average gas drainage concentration is 2-3 times of that before the composite protective layer mining. [ABSTRACT FROM AUTHOR]

Tree-type borehole drilling (TTBD) is a novel stress relief method for stimulating methane drainage from coal in underground coal mines. This paper is a report on studies that analyzed the permeability enhancement capabilities of tree-type boreholes in coal seams and presents a precedent-setting industrial trial of this new method in a 200-m section of a drainage roadway in a coal mine, the Shoushan coal mine in Henan province, China. Detailed simulation results indicated that after coal seams were stimulated using the TTBD method, a large number of fractures were initiated around the tree-type boreholes. These fractures propagated along the direction of maximum horizontal stress and formed highly permeable flow channels for methane transport from the coal into the tree-type sub-boreholes. The fractures gradually became shorter along the length of the sub-boreholes. As the sub-boreholes were shortened, the area fractured and the number of induced fracture decreased rapidly. Conversely, the fracture density and the value of homogeneity coefficient, β, increased. The industrial trial showed that compared with gas drainage from a conventional borehole in the Ji15−17 coal seams, the gas production rate from a single tree-type borehole was 4.7 times faster and the percentage of methane in the gas produced was 1.7 times higher. In addition, the borehole drainage attenuation time was 2.5 times longer for the tree-type boreholes. The total volume of gas production produced from 238 tree-type boreholes in a 200-m section of roadway was over 70,000 cubic meters, 1.4 times the methane extracted by 938 conventional boreholes in an adjoining 200-m section of the same roadway. In addition, the number of boreholes required to drain 1.4 times as much gas was 75% smaller. These results have provided support for the appreciation and application of this new technique for improving underground coal mine methane drainage. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The life cycle of mining results in various patterns of surface deformation as it progresses through development, production, and reclamation. Therefore, the spatial–temporal patterns of ground deformation provide a crucial indicator to understand the mining activities, related geohazards, and environmental restoration. This study investigates the decadal deformation (2012–2022) of three coal mines during different stages of mines' life cycles in Henan, China, using radar interferometry with Radarsat-2 and Sentinel-1 data. The results reveal multiple deformation patterns across different areas: the Changcun mine area changed from ground subsidence to uplift following the termination of exploitation in 2016; the Xiadian mine area has been continuously developing over the past decade, resulting in a cumulative subsidence of 55.6 mm; and the Liyuan mine area exhibits surface rebound at a rate of 7.9 mm/year since its closure in 2007. We also probe the mining geometry of the production process by using a rectangular model. This study highlights the significance of long-term InSAR observations and deformation modeling in elucidating the mining operation dynamics of small mining zones in their production, transition, and post-closure periods, thereby facilitating the management of small-scale mining. [ABSTRACT FROM AUTHOR]

A rock burst accident occurred on coalface 13230 of the Gengcun Coal Mine in Henan Province. Through a field investigation, theoretical analysis, and microseismic monitoring, we studied how the rock burst, which was caused by overall seam floor slip and instability, occurring under an ultrathick conglomerate. Because the overlying ultrathick conglomerate in the mined-out zone close to coalface 13230 had been inadequately mined, the leading section of the coalface was under a high level of stress. Combined with the tectonic stresses from the F16 faultage and the soft floor structure, these factors caused the floor of this coalface to trigger the overall slip-type rock burst. In this paper, an estimation model of the ultimate bearing capacity of a seam floor under an ultrathick conglomerate and the advancing abutment pressure on the coalface is presented. This model is used to show that the ultimate bearing capacity of the seam floor on coalface 13230 is 26.3 MPa, and the abutment pressure is far more than the floor bearing capacity. We also present pressure relief and reinforced supporting measures, which can effectively prevent floor slip-type rock bursts from occurring. The results of this study provide a reference for the prevention and control of floor slip-type rock bursts in coal mining under an ultrathick conglomerate. [ABSTRACT FROM AUTHOR]

For the characteristics of high frequency and strong suddenness of dynamic disasters in deep coal mines, the traditional detection and evaluation techniques applied to shallow coal mine failed to accurately judge the risk degree of disasters. Therefore, it is of great significance to use advanced detection technologies and appropriate evaluation methods to improve the accuracy and efficiency of risk assessment in the process of coal mining. The present paper applies the rapid detection and multi-source dynamic detection technologies used in the field of mining with the purpose of improving the reliability of detection technologies for typical dynamic disaster. In this study, the data fusion technology was used to analyze data obtained from laboratory experiments, engineering survey, detection and historical data, so as to form the final dynamic and static indicators. Then, the new combined evaluation models with time series of coal and gas outburst as well as rock burst were established respectively to carry out the comprehensive risk evaluation using the least-squares method and the time-varying weight method. After the comprehensive analysis on the results of the above two evaluation models, the risk areas of the typical dynamic disasters were judged and classified. Finally, the evaluation models were coded to build an early-warning software platform that could achieve automatic evaluation and the actual 3D visualization of coal mining areas. The early-warning software platform was applied to risk assessment of dynamic disasters in Gengcun Coal Mine in Yima City, Henan Province, China. The results of the 6-month experiment showed that the risk assessment accuracy and reliability of the proposed evaluation models was 100% and 90% respectively, which indicates that the newly developed approach is reliable and can be recommended for applying in more coal mines to improve the process safety risk control. [ABSTRACT FROM AUTHOR]

Coal mine methane (CMM) drainage is an effective method to curb the occurrence of coal and gas outburst and gas explosion, to reduce the amount of greenhouse gas emission, and to make full use of the clean energy(methane). Sealing in-seam horizontal boreholes plays a vital role in CMM drainage. Reasonable sealing length is an important factor to achieve high extraction efficiency and reduce the cost of construction. To determine the minimum reasonable sealing length of drainage boreholes, the radius of the fracture zone was obtained based on the ideal elastoplastic model, and this radius was taken as the minimum sealing length. The influencing factors of the minimum sealing length were analyzed and engineering verification test was taken in Zhongmacun mine in Henan province, China. The research results show that the minimum reasonable sealing length should be longer for a larger radius of the coal roadway and the coal seam with a deeper buried depth, while the minimum reasonable sealing length can be shortened with the increase of uniaxial compressive strength and the supporting stress of the coal roadway. The 11.07 m of sealing length calculated by theories was basically consistent with the 12 m of sealing length verified by the method of drilling cuttings. The reasonableness of sealing length (12 m) was verified by the test results of methane concentration and flux within 40 days. All those outcomes can provide references for other mines to determine the minimum reasonable sealing length of in-seam boreholes for CMM drainage. [ABSTRACT FROM AUTHOR]

Extraordinarily severe coal mine accidents (ESCMAs) are characteristized by thirty fatalities or more in one accident. In this paper, such ESCMAs are analyzed using 188 cases which occurred in Chinese underground coal mines. The analysis shows that the number of ESCMAs and the death toll have decreased steadily over time. Gas explosions, mine water inrushes, and coal dust explosions are the three major types of ESCMAs. Among the causes of ESCMAs, inadequate implementation of safety measures, deliberate violations and electromechanical equipment faults are the three top causes of ESCMAs, accounting for 27.13 %, 21.81 %, and 15.96 % of incidences, respectively. Meanwhile, ESCMAs frequently occur in the heading face, especially gas explosions, mine water inrushes and coal and gas outbursts. Furthermore, ESCMAs reoccur often in certain provinces, such as Shanxi, Henan and Heilongjiang, and mostly during November and December in each year. The results of statistical studies have presented useful information for the prevention of ESCMAs in order to reduce the probability of such disastrous accidents. [ABSTRACT FROM AUTHOR]

Copyright of Hydrological Sciences Journal/Journal des Sciences Hydrologiques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to comprehend the dynamic disaster mechanism induced by overburden rock caving during the advancement of a coal mining face, a physical simulation model is constructed basing on the geological condition of the 21221 mining face at Qianqiu coal mine in Henan Province, China. This study established, a comprehensive monitoring system to investigate the interrelations and evolutionary characteristics among multiple mechanical parameters, including mining-induced stress, displacement, temperature, and acoustic emission events during overburden rock caving. It is suggested that, despite the uniformity of the overburden rock caving interval, the main characteristic of overburden rock lies in its uneven caving strength. The mining-induced stress exhibits a reasonable interrelation with the displacement, temperature, and acoustic emission events of the rock strata. With the advancement of the coal seam, the mining-induced stress undergoes four successive stages: gentle stability, gradual accumulation, high-level mutation, and a return to stability. The variations in other mechanical parameters does not synchronize with the significant changes in mining-induced stress. Before the collapse of overburden rock occurs, rock strata temperature increment decreases and the acoustic emission ringing counts surges with the increase of rock strata displacement and mining-induced stress. Therefore, the collaborative characteristics of mining-induced stress, displacement, temperature, and acoustic emission ringing counts can be identified as the precursor information or overburden rock caving. These results are in good consistent with on-site situation in the coal mine. [ABSTRACT FROM AUTHOR]

• This study mainly focuses on extraordinarily severe gas explosion accidents (ESGEAs) in Chinese coal mines. • Disorganized ventilation fan management and illegal blasting were the most prominent causes of ESGEAs. • ESGEAs are linked with the operating locations, occurrence time, regions and ownership of the coal mines. Extraordinarily severe gas explosion accidents (ESGEAs) (thirty fatalities or more in one accident) have a high occurrence frequency in Chinese coal mines. There are 126 ESGEAs that occurred in China from 1950 to 2015, and they were investigated through statistical methods in this study to review the overall circumstances and to provide quantitative information on ESGEAs. Statistical characteristics about accident-related factors, such as gas accumulation, ignition sources, operating locations, accident time, coal mine regions and coal mine ownership, were assessed in this paper. The statistical analysis shows that disorganized ventilation fan management was the most frequent cause of gas accumulation in ESGEAs, while illegal blasting was the most prominent cause of the ignition source in ESGEAs. Furthermore, ESGEAs were found to occur frequently in certain provinces (e.g., Shanxi, Henan and Heilongjiang) and during November and December of the year. Moreover, most accidents and the largest death tolls generally occur in state-owned coal mines. Based on the results of statistical studies, some countermeasures were proposed in this study. [ABSTRACT FROM AUTHOR]

According to the characteristics of "Three Soft" outburst coal seams in the Henan area with large gas content, poor air permeability, and extremely difficult extraction, the hydraulic fracturing and punching technology of soft coal with packer tool string sealing method was studied. Xinzheng Coal Electric Power Company is a coal and gas outburst mine, and the second coal seam is a typical soft outburst coal seam. In 14201, upper bottom drainage roadway, which has a broken top plate, a test of penetration hydraulic pressure thrust-enhanced permeability technology based on packer sealing mode was carried out. The average concentration in the press-punching area was 4.8 times that in the non-press-punching area (to be tested), and the average pure volume of 100 holes in the test area was 42 times that in the untested area. During hydraulic pressure punching in the test area, affected by fracturing disturbance, the concentration and purity of the test area and the adjacent test area significantly increased. The test verifies that the large range of fracturing communication cracks at the same time through the interception hole punching plays a synergic permeability and pressure relief effect, providing a new idea and technical support for the hydraulic permeability increase technology in this area. [ABSTRACT FROM AUTHOR]

In the process of pre-discharging gangue via the dual-energy X-ray coal and gangue sorting device, the pseudo-medium coal in the raw coal will be identified as gangue and then discarded. Clean coal can be recovered and resource waste can be reduced via the crushing and re-separation of pseudo-medium coal, which is the critical step in the treatment procedure of a coal preparation plant. By virtue of dual-view visible-light imaging, an image identification method was proposed to recover the pseudo-medium coal identified as gangue by dual-energy X-ray. The pseudo-medium coal was determined based on the differences in coal and gangue surface organization and reflective properties. Linear dispersion was used to evaluate the distinguishability of features, and the elements were sorted. The recognition effect of the classifier model on pseudo-medium coal and gangue under different feature combinations was experimentally observed. The results unraveled that the identification rate of mixed samples of pseudo-medium coal and gangue that were selected from Dayugou Coal Mine in Zhengzhou City, Henan Province, could reach 95% using the method herein. The invention can effectively recover pseudo-medium coal from the waste rock pre-discharged by the dual-energy X-ray sorting device, realizing the multi-classification of raw coal. [ABSTRACT FROM AUTHOR]

Emergency management of coal mines requires enhanced synergy among departments, institutions, and enterprises, which means overall efficiency in management. In this study, a regional coal mine emergency (CME) management synergy system was established; the synergy theory was adopted to construct the order parameter index system of the regional CME management synergy subsystems. Moreover, the order degrees and synergistic degrees of the regional CME management synergy subsystems in Henan Province, China, in the period 2015-2019 were quantitatively measured and analyzed using the composite system synergy model. The results show that the order degrees of regional CME management synergy subsystems and the synergistic degree of the composite system increase overall during the inspection period. With the gradual formation of the regional CME management synergy mechanism, this period has witnessed a steady improvement in both the synergy value and the considerable synergistic effect. [ABSTRACT FROM AUTHOR]

Coal mines in Pingdingshan mining area, Henan province, China, are commonly mined at a great depth up to 1000 m, and inevitably reside in high temperature, high pressure, high permeability, strong mining disturbance, and strong time effect environment. Support structures of the mines in the area are vulnerable to failure and destruction while roadway stability has been a long-standing issue in the region. Based on the specimens collected from the roof of the return-air rise at Pingdingshan No.1 coal mine, here, we investigated the creep characteristics of sandy mudstone under triaxial conditions and developed a constitutive relationship to predict the creep behavior. Parameter identification and sensitivity analysis were performed to determine the influential factors of creep deformation. We showed that the creep deformation and steady-state creep rate at Pingdingshan coal region grow as axial stress is elevated while descend with increased confining pressure. However, the maximum creep deformation of sandy mudstone increases with a higher confining pressure. Thereby, stress difference, elastic modulus and coefficient of viscosity are the major parameters controlling creep deformation. Hence, it is important to enhance the support strength and mechanical properties of the surrounding rock, to better the roadway stability. In addition, numerical simulation was also conducted for simple excavation geometries to analyze different support structures. On this basis, the "cable bolts steel arch, deep and shallow reinjection, floor pressure relief and local reinforcement" scheme was proposed and field practice showed promising results. The findings in this study can be used to guide the support design for the deep soft rock roadway (DSRR). [ABSTRACT FROM AUTHOR]

Reinforcement with grout as an environmentally friendly technology has played a key role in underground coal mining. The risk of the water inrush into coal mines can all be reduced by grouting. A model that integrates a geographic information system (GIS), distribution of quantity of grouting injected, and water inflow correlation method is proposed here to evaluate the effects of grouted reinforcement in coal mining. The temporal and spatial characteristics of the volume of grout injected and water yield of aquifers are analyzed by using the GIS, and the rate of filling of cement slurry and its distribution characteristics are determined. The effects of grouting on the aquifers which has been carried out to reduce their permeability are determined by comparing the spatial temporal variations in the volume of the grout injected, water yield, and rate of filling of the cement slurry. The method was applied in a case study in a coalmine in Henan province, China, in which the risk of the water inrush from karst aquifers has been reduced by grouting. There are three limestone aquifers, namely, L8, L10, and L11 which underlie an exploitable coal seam. The result indicates that most of the cement slurry is consumed when the water yield is 20 to 30 m3/h; and that there are minimal changes of the electrical properties of the rock stratum under coal seam when the water yield of L11 is low within the range of 40 m. The resistivity of the aquifers before and after grouting and their spatial characteristics are tested by using the transient electromagnetic method (TEM), and this shows that there are no areas with low resistivity. The electrical properties of the strata at a depth that ranges from 40–80 m with transverse homogeneity show that Aquifers L10 and L11 have been transformed into aquicludes. The reinforcement effect of aquifers with grout is good. [ABSTRACT FROM AUTHOR]

Drilling of large-diameter boreholes is regarded as an effective measure for rockburst prevention. By investigating the morphological characteristic and evolution of plastic zone in borehole surrounding rock, the pressure-relief mechanism of large-diameter borehole was ascertained, and the engineering application of large-diameter boreholes was assessed in the 13230 working face of Gengcun Coal Mine, Henan Province, China. The results showed that (1) the plastic zone in surrounding rock of borehole appear as circular, elliptical, and butterfly shapes, in which the maximum size of the butterfly wings of the plastic zone is several times larger than the borehole diameter; (2) under certain stress conditions, multiple large-diameter boreholes distributed in coal seam with rockburst risk lead to the generation and coalescence of large-range butterfly-shape plastic zone. They reduce the stress concentration and capacity for storing elastic energy of coal seam, thus reducing the rockburst risk of the coal seam; (3) large-diameter boreholes significantly decrease the stress concentration in front of the 13230 working face and improve the stress environment in the head entry, promoting the safe mining of the working face. [ABSTRACT FROM AUTHOR]

Uncertainties in the basic theory of shallow mining that continues to be used in deep mining result in frequent engineering disasters with deep characteristics. Thus, it is necessary to elucidate the mechanism of mechanical deformation and failure behavior of coal from shallow to deep depths. Coal samples from the same coal seam in the Pingdingshan mining area of Henan Province were obtained at depths of 300 m, 600 m, 700 m, 850 m, and 1050 m. Direct tensile tests were conducted on the coal samples obtained at different depths. The tensile strength exhibits as low decreasing trend with increasing depth, reaching a minimum at 1050 m. This variation trend is consistent with that of acoustic emission cumulative ring-down counts and the cumulative energy measured during tensile tests on coal samples obtained at different depths. These conclusions provide a reference for the differences between the mechanical behavior of shallow and deep coal, which has both theoretical and engineering significance. [ABSTRACT FROM AUTHOR]

The essence of both rockburst and coal and gas outburst lies in fast energy release. In order to explore the energy action mechanism of coal and gas outburst induced by rockburst in rockburst and coal and gas outburst combined mines, the split Hopkinson pressure bar (SHPB) experimental device was firstly used to conduct uniaxial impact failure test of coal specimens prone to outburst under different strain rates, and their energy dissipation laws under impact loading were obtained. Next, under the engineering background of coal and gas dynamic phenomena induced by rockburst with different intensities in Xinyi Coal Mine and Pingdingshan Coal Group No. 12 Colliery in Henan Province and Dingji Coal Mine of Huainan Mining Group in Anhui Province, experimental study results were combined with numerical simulation analysis to discuss the energy mechanism of coal and gas outburst induced by rockburst. The study results show that the outburst can be divided into two different processes—critical outburst and outburst—according to the evolution law of outburst energy, and the critical energy conditions for coal and gas outburst are proposed. The minimum destructive energy range for the critical outburst of coal mass is obtained as (5–10) × 104 J/m3. Under some low gas, high stress, or strong disturbance conditions, applied loads can become the main energy sources causing critical failure and even crushing and throwing of coal mass. The coal mass will present an interval splitting structure under dynamic loading, which is obviously different from the failure mode of coal mass under static actions. [ABSTRACT FROM AUTHOR]

Gas explosion, which is the main type of accidents reported in coal mines, comes with serious economic and safety consequences. The present work adopts the "glass heart" model for assessing the vulnerability of coal mines to gas explosions based on a constructed gas explosion vulnerability assessment index system. The proposed index system is applied to a coal mine in Henan Province, China, as an example. The original disturbance index is augmented by including the energy release index factor. The Delphi method is employed by six experts to score the index factors according to a scoring standard. Data analysis and processing yield a gas explosion vulnerability score of 0.431 for the example mine. Accordingly, the mine is classified as grade II, indicating that the mine is likely to result in casualties and/or property loss. A comparison of the assessment results with those obtained via an analysis of records pertaining to previous gas explosion accidents indicates that the proposed assessment of gas explosion vulnerability by means of the "glass heart" assessment model is realistic. The "glass heart" vulnerability assessment method offers a new perspective and methodology for assessing the vulnerability of coal mines to gas explosion and conducting coal mine risk classification. [ABSTRACT FROM AUTHOR]

Coal mining may affect the hydrochemical characteristics and evolution processes of groundwater, leading to a deterioration in groundwater quality. This study was conducted to understand the hydrochemical characteristics and determine the hydrochemical processes controlling the karst groundwater hydrogeochemistry in Carboniferous Taiyuan formation in the Pingdingshan coalfield, Henan Province, China. Statistical techniques and conventional methods were utilized to gain a comprehensive understanding of the hydrogeochemical processes of karst groundwater. Results showed that the groundwater was fresh water, and was slightly acidic-to-slightly alkaline. The main cations were Ca2+ and Na+, and the predominant anions were HCO3− and SO42−. Most of the groundwater was predominantly of the Ca–HCO3 type. Principal Component Analysis (PCA), ion correlation analysis, and conventional graphic methods (Piper and Gibbs diagrams) indicated that the dissolution of silicate, gypsum, and carbonate minerals controlled the formation of Na+, Mg2+, Ca2+, SO42−, and HCO3−. Meanwhile, cation exchange was another important process regulating karst groundwater quality. Moreover, the concentrations of SO42− and NO3− were high, suggesting that the karst groundwater in this study area had been affected by anthropogenic activities, such as agriculture and mining. To avoid water inrush and keep mines east of the study area safely operational, the Guodishan faults within the mining area should be grouted to cut off the connection between limestone aquifers in the east and west study areas. In addition, it is necessary to strengthen the scientific research on fertilizers that allow plants to absorb nitrogen rapidly and control the amount of fertilizer used to protect the groundwater from pollution. The results of this study are helpful for the prevention and control of water disasters, and are beneficial for groundwater resource protection in the Pingdingshan mining areas. They will also provide a reference for similar studies by other mining hydrogeologists across the world. [ABSTRACT FROM AUTHOR]

In order to reveal the occurrence mechanism of coal and gas outburst and optimize the measures to prevent the disaster, a coal mine in Henan Province was undertaken as the research background. Based on the geological and mining conditions of the coal mine, the gas geological analysis method is applied to determine the outburst occurrence and to classify the risk levels. A multifactor pattern recognition method is used to determine the risk probability of the dynamic disasters such as coal and gas outburst. The relationship between geological structure, rock mass stress, and mine dynamic hazards is determined using geo-dynamic division method and FLAC3D numerical simulation. The occurrence and manifestation characteristics of the dynamic hazards are determined. COMSOL Multiphysics software is used to evaluate the original prevention measures and to optimize the measures. The research results determine the main influencing factors and regional distribution law of coal and gas outburst, which is of great significance to the risk prediction and prevention of dynamic disasters such as coal and gas outburst. [ABSTRACT FROM AUTHOR]

The failure part of 10·20 large coal and rock outburst accidents is analyzed in Daping coal mine of Zhengzhou Coal Group of Henan province by ANSYS finite element software. The amount of energy released is calculated before and after the failure of the rock mass near the fault in the plane strain, and the energy released is 1.0757 × 109 J. Based on the law of conservation of energy, the theoretical ejection velocity of the rock mass in failure is calculated under the energy dissipation (30%) and no energy dissipation. The results show that the numerical calculation results are basically consistent with that of the on-site engineering accidents, indicating that ANSYS and the energy analysis approach are applied to the field of coal mining. Therefore, based on the method of energy analysis, the risk of impact failure of the remaining coal pillars near the fault is evaluated, which provides a scientific basis for coal pillar protection and mine safety. [ABSTRACT FROM AUTHOR]

Coal and gas outburst disaster of the No. B-1 Coalbed, Henan, China, have lasted for nearly 60 years, and the threat will become more and more serious as mining depths continuously increase. However, coal and gas outburst characteristics and factors of the coalbed have not been studied in detail. To effectively prevent and control coal and gas outburst, we analyzed the type, intensity, location and precursors of coal and gas outburst occurring in the No. B-1 Coalbed. Moreover, the effects of geological conditions (burial depth, faults, folds, coalbed thickness and dip) and mining disturbances on coal and gas outburst were studied. The results showed that these outburst accidents were mostly typical, small-sized and medium-sized outburst, which mainly occurred at the coal roadway working faces. There were many precursors such as blasting sound, changes in coal structure, and abnormal gas emission prior to the accidents. Within a burial depth of 500 m, the average outburst intensity had a stronger correlation with the burial depth, which was more obvious at a burial depth of 301∼400 m, and less obvious at a burial depth of 401~500 m. However, the distribution of these outbursts barely changed within the burial depth. Up to 99.15% of coal and gas outburst occurred at faults, folds, and areas with changes in coalbed thickness and dip. Up to 68.25% were induced by blasting and 18.04% occurred during shelving, coal-shoveling and no operation. The No. B-1 Coalbed was characterized by delayed outbursts. Moreover, specific suggestions were recommended for the prevention and control of coal and gas outburst. The study is useful to government regulators and staffs engaged in the prevention and control of coal and gas outburst. [ABSTRACT FROM AUTHOR]

Understanding the mineralogical and chemical characteristics of stone coal is imperative for exploring the thermal storage characteristics of stone coal. Two types stone coal (SCwt and SChc) were sampled from the pond of a stone coal mine in Henan province (China), and the chemical composition, phase composition, and thermal behavior of the stone coal were investigated. Furthermore, the petrography of the stone coal was studied in detail. The mineral phases of the stone coal were quartz, kaolinite, roscoelite, and goethite, as distinguished by reflected light microscopy and further proven by scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The thermal conductivity of SCwt was 0.19 W m−1 K−1, while that of SChc was 0.24 W m−1 K−1. Stearic acid (SA) was blended with SCwt and SChc to prepare SA/SCwt and SA/SChc composites via an impregnation method, respectively. The thermogravimetric (TG) curves show that the loading capacity of SChc, at 17.40%, is higher than that of SCwt (16.63%). The thermal energy storage capacities of SA/SCwt and SA/SChc composites were 29.21 J g−1 and 33.02 J g−1 according to a differential scanning calorimetry (DSC) analysis. Therefore, SChc is a potential candidate for thermal storage applications due to more obvious thermal storage characteristics, including higher thermal conductivity and loading capacity. [ABSTRACT FROM AUTHOR]

Karst groundwater represents important natural resources and is the main target groundwater of drainage in the coal-mine fields of Northern China. It is easily influenced by external environment. However, the evolutionary processes and those factors impacting the Ordovician carbonatite groundwater are not well understood. To investigate the geochemical evolution of Ordovician carbonatite groundwater, a typical piedmont karst water system located in Taihang Mountain, Henan Province, China was selected for study. A series of groundwater samples were collected and analyzed. Isotope and chemical data were used to analyze the hydrochemical evolution of Ordovician groundwater in the research area. The results showed that the main ions of Ordovician groundwater are HCO3−, SO42−, Ca2+, and Mg2+, and the predominant water chemical type is HCO3–Ca·Mg, with some HCO3–Mg·Ca and HCO3·SO4–Ca·Mg. The isotopic characteristics indicated that the groundwater is mainly recharged by precipitation. Groundwater geochemistry changed after rainfall infiltrated the aquifer. The changes to the Ordovician groundwater were caused by the reaction of water and rock, and the effect of evaporation is relatively small. The main source of Ca2+, Mg2+, SO42−, and HCO3− is the dissolution of calcite, dolomite, and gypsum. Na+ and Cl− come from the dissolution of halite. The groundwater flow field also is an important factor in the control of groundwater evolution. Coal-mine production alters the groundwater flow field, and leads to the changes of ion content in areas around the coal mine. The evolution processes of the main ion contents in groundwater have a significant relationship with the groundwater flow. TDS and Cl− increased with the seepage of groundwater, and the high values are around the stagnant and discharge area of groundwater. The Ca2+ content in groundwater decreases first and then increases to the maximum at the drainage area of coal mine along the groundwater flow field affecting the effect of CO2. SO42− contents increased continuously and significantly, that is effect by the mining operation, over a long period. [ABSTRACT FROM AUTHOR]

The horizontal bending angle of scraper conveyor has a great influence on the running resistance, the current consumption, coal winning efficiency of the working surface, etc. Approximately 1–3° is usually the range of horizontal bending angle, but does not indicate the optimum bending angle of the coal mining face. To find the optimal horizontal bending angle, an optimization method is proposed. A mathematical calculation model of the running resistance of the scraper is established based on the direction of the shearer operation. Then, a method of adjusting the step size of the search by inertia weight and expanding fly distance range obeying the t-distribution is proposed based on the basic bat algorithm (BA). Finally, an industrial application was conducted in 21220 Changcun fully mechanized coal mining face, Henan Province. The results show that the current consumption by the scraper conveyor was reduced by 31% when the horizontal bending angle of the S-bending area was 0.66°. Meanwhile, the theoretical current has good consistency with the experimental data, and the average absolute error was 3%. [ABSTRACT FROM AUTHOR]