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This study analyzes static and dynamic ruptures in deep coal mining and their impacts on working faces. Using a 2-D numerical model with PyLith, we evaluate the energy, stress disturbances, and seismic wave effects induced by a nearby reverse fault. By pioneering PyLith in induced seismicity research, we provide critical insights into the interactions between mining operations and geological structures. The model simulates fault slip processes and their effects on the working face, focusing on stress changes, energy concentration, peak particle velocity (PPV), and peak particle acceleration (PPA) under varying conditions of mining-induced seismicity. Static deformation due to fault slip caused significant stress changes on both the ceiling and floor of the working face, with stress values ranging from 0.9 MPa to 39 MPa in σxx, 0.6 MPa to 14.7 MPa in σxy, and 1.1 MPa to 22 MPa in σyy. Energy concentration was observed at the corners of the working face near the fault. Dynamic analysis revealed rupture durations ranging from 250 ms to 670 ms, with rupture velocities decreasing from 1.25 km/s to 0.62 km/s as the characteristic slip distance (Dc) increased. Seismic waves showed that both PPV and PPA decreased with increasing Dc. Our findings highlight the necessity of advanced numerical modeling to predict and manage hazards associated with mining-induced seismic events. Additionally, the study emphasizes the importance of designing robust support systems and implementing safety measures to ensure the stability and safety of mining operations under seismic conditions. [ABSTRACT FROM AUTHOR]

As the depth of mine excavation increases, ventilation shifts from an easy to a challenging phase. To address potential issues of high temperature and low airflow in the underground working face of Yanqianshan Iron Mine, 2 optimization plans were proposed with the -269 m level as the research subject. A 3D visualization simulation model of the underground ventilation system was created, and mine ventilation system network analysis software was used for 3D simulation and network calculations to simulate and analyze the optimization plans. Numerical simulation results of the optimized ventilation system showed that Plan 1 increased the average airflow in the northern area of the -269 m roadway by 1. 13 m³/s and decreased the temperature by an average of 0. 14 ℃ . Plan 2 increased the overall airflow in the -269 m roadway by an average of 5. 51 m³/s, with a temperature reduction of 0. 34 ℃ in most roadways near the mining area. A comparison indicates that Plan 2 provided a greater increase in airflow and a wider impact range for temperature reduction. Both plans improved the ventilation system, offering valuable reference for optimizing underground ventilation systems in most domestic underground mines. [ABSTRACT FROM AUTHOR]

High ground stress is an inevitable challenge in deep mining. To ensure safe and efficient mining operations in the high-stress environment of Xincheng Gold Mine, the Swedish LUT ground stress measurement instrument was used. A total of 6 borehole cores at the -830 m, -930 m, and -1030 m levels of Xincheng Gold Mine were measured using the stress relief method. The LUT-str dedicated rock stress calculation program was employed for comprehensive analysis of the test results. Stereographic projection software was used to create stereographic projection diagrams of the principal stress directions at the measurement points, and linear regression was applied for regression analysis of the stress values from the 6 measured points. The research result shows that the ground stress field in Xincheng Gold Mine is primarily horizontal tectonic stress. The surrounding rock in the mining area contains numerous joints and fissures, leading to more fragmented and weathered rock after excavation, which makes phenomena like spalling more likely. Therefore, timely support is recommended after excavation. This study provides fundamental data and references for safe construction of deep shafts, rational support design, and deep mining operations, while also serving as a model for shaft excavation and mining in similar mines. [ABSTRACT FROM AUTHOR]

With the rising demand for mineral resources and the gradual depletion of shallow mineral resources in China, it has become an inevitable trend to mining new mineral resources by expanding to the depths. First, for the many challenges faced by the traditional rock drilling and blasting process in deep mining, the non-explosive continuous mining technology and equipment for hard rock deposits are introduced. Then, taking a deep hard rock mine as example, the application practice of non-explosive continuous mining technology are introduced in detail with the positive results brought about, which provides a case study for the non-explosive continuous mining of deep hard rock deposits; Finally, based on the practical experience and combining with cutting-edge technologies such as artificial intelligence, the ore slurry-making hydraulic transportation technology is proposed, which is expected to provide a more efficient and environmentally friendly solution for lifting ores in deep mines, and to further optimize and enhance the mining efficiency and safety of deep mines. [ABSTRACT FROM AUTHOR]

The fluid–solid coupling effect is an important factor which cannot be ignored to study the surface subsidence of deep coal seam mining in the area with abundant underground water. To study the influence of boundary permeability characteristics on surface subsidence in deep near‐horizontal coal seam mining under the effect of fluid–solid coupling, the pore water pressure field, vertical stress field, surface subsidence, and vertical displacement of a rock seam during deep mining under different permeability boundary conditions were analyzed based on fluid–solid coupling theory, taking the 3−1501 working face of Erdos Hongqinghe coal mine as an example. The results revealed that the permeability characteristics of different hydraulic boundaries affected the pore water pressure, vertical stress in the rock layer, and surface subsidence during deep mining. Moreover, the trends of pore water pressure, vertical stress, and surface subsidence of a fixed‐head permeability boundary were largely the same as those under impermeable boundary conditions, but the calculated results of the fixed‐head permeability boundary were lower than those for the impermeable boundary at the same depth. The maximum surface subsidence for the fixed‐head permeable boundary condition and the impermeable boundary condition was 879 and 925 mm, respectively, which were 239 and 285 mm higher than those obtained when the fluid–solid coupling effect was neglected (an increase of 37.3% and 44.5%, respectively). The field monitoring trend for the subsidence basin aligns closely with the subsidence basin trend under the influence of fluid–solid coupling. Considering the constant head permeable boundary conditions in the context of fluid–solid coupling yields accurate surface subsidence results. The results have provided a theoretical basis for the analysis and prediction of coal mining surface subsidence considering the fluid–solid coupling effect. [ABSTRACT FROM AUTHOR]

Shallow resources are becoming increasingly depleted, deep resource exploration has become a global strategy. The design and testing of deep in-situ core samples are prerequisites for exploring deep resources; however, no in-situ condition-preserved coring and testing techniques and tools have been reported yet. Here, the first deep in-situ conditionpreserved coring system (with the preservation of pressure, temperature, substance, light, and moisture) was developed that considers the effects of high water pressure and formation dynamic loads, along with an in-situ condition-preserved testing system. A pressurepreserved controller was designed, achieving the ultimate capacity of 140 MPa and 150 ℃. A temperature-preserved coring system combining active heating and passive insulation was constructed, realizing temperature preservation from room temperature to 150 ℃. Three generations of film-formation principles and methods were designed, achieving an excellent quality preserved rate, moisture preserved rate, and visible light barrier rate. Moreover, a deep in-situ condition-preserved coring system, and a simulated coring platform for large cores under in-situ environments was fabricated. A non-contact testing system was derived to cut and prepare specimens under in-situ environment and to perform non-contact non-destructive testing and true triaxial testing. The research findings can be successfully applied to deep coal and gas development, deep oil and gas resources assessment, and deep-sea sediment prospecting, achieving excellent application outcomes. This study provides important theoretical, technical and hardware support for deep in-situ rock physics and mechanics research and deep resource exploitation. [ABSTRACT FROM AUTHOR]

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Based on the thermo-fluid-solid coupling law of coal and gas outburst in deep mining, a numerical model of coal and gas outburst is established, and the response of multi-physical parameters in the whole process of coal and gas outburst under high stress condition is analyzed. The results show that the response rule of the stress field around the outburst hole is initial vibration-sudden attenuation-late stability. The decreasing rate of gas pressure is negatively correlated with the length of the outburst hole. In the outburst process, the adsorbed gas contained in the crushed coal quickly desorbed and expanded to do work, resulting in a decrease in temperature; the areas with significant changes in permeability after outburst can be divided into sudden increase area, medium increase area and increase area. With the increase of stress, the proportion of elastic potential in total coal and gas outburst energy increases, and the proportion of elastic potential is positively correlated with stress.

The rupture of super-thick key strata is a crucial factor in triggering mine dynamic disasters. Investigating the impact of their non-uniform thickness on mining-induced stress environments and rupture dynamic loads, and further revealing the mechanism of dynamic and static loading on rock burst pressure, is the theoretical foundation for predicting rock burst risks and disaster prevention and control. This paper investigates the non-uniformly thick “bow-shaped” super-thick key strata in the Binchang mining area of Shaanxi. Through comprehensive theoretical analysis and numerical simulation, it analyzes the mechanical principle of abnormal stress concentration in the coal rock mass beneath the “bow-shaped” super-thick key strata, clarifies the influence of the “bow-shaped” morphology on the rupture characteristics of the super-thick key strata and reveals the mechanism of dynamic and static load superposition in the area beneath the “bow-shaped” formation, leading to rock bursts. Based on the study above, a method for predicting the disaster risks caused by the rupture of “bow-shaped” super-thick key strata is proposed. The results show that in the convex area under the “bow-shaped” formation of the super-thick key strata, the high stress is exceptionally concentrated, increasing the coal rock body stress by an additional 22.1 MPa, with an increase rate of up to 56%, which is the fundamental reason for the high static load formation in the underlying coal-rock body. At the same time, the principal stress in the concave area of the “bow-shaped” formation concentrates and undergoes significant deformation, increasing the risk of strong dynamic loads due to rupture. Under the combined action of dynamic and static loads in the non-uniformly thick “bow-shaped” super-thick key strata, the rock bursts are likely to occur in the pillar and roadway areas. The proposed method for predicting the disaster risks due to the rupture of “bow-shaped” super-thick key strata effectively guides the disaster prevention and control in high-risk mining areas prone to rock bursts. Additionally, the distributed fiber optic field measurement results validate the intrinsic connection between the rupture of super-thick key strata and the generation of dynamic loads.

Roof with weak interlayer has significant influence on the stability of deep gob-side entry driving, to effectively control the separation of roof with weak interlayer in deep gob-side entry driving under high deviatoric stress, based on the mechanical experiment of composite specimen with weak interlayer and numerical simulation experiment of gob-side entry driving under the influence of mining, the influence of the thickness, number and position of weak interlayer and the evolution law of roof separation under high deviatoric stress conditions are obtained, the main reasons for separation of the roof with weak interlayers of deep gob-side entry driving are elucidated. The key points for controlling the roof with weak interlayer are analyzed using the mechanical model of cantilever beams under the support load and coal pillar support load, and the separation control method is subsequently proposed. The results show that the influence on the deterioration of the mechanical properties of the composite gradually becomes larger with the increase of the thickness and the number of layers of the weak interlayer, the influence on the deterioration of the composite with weak interlayer at the low position is stronger than that at the high position. The fracture of the composite specimen is produced by the weak interlayer, and the characteristics of the fracture development are different with its thickness, the number and position. The main shear failure zone generated at the left shoulder corner of the roof and connected to the adjacent rock failure area near the weak interlayer after gob-side entry driving, resulting in the separation of the weak interlayer, and the development morphology of main shear failure zone and non-coordinated degree deformation of roof vary with the deviation angle of principal stress and the thickness, number and position of weak interlayers, which revealed the instability mechanism of roof with weak interlayer of deep gob-side entry driving. The mechanical model of roof separation under the support load and the supporting load of coal pillar was established, which found that the separation of weak interlayer in the anchorage zone was 79% lower than that outside the anchorage zone, the degree of influence on the spatial distribution of separation under different influencing factors is as follows: supporting load of pillar, supporting load of roof, elastic modulus of the roof. According to the separation law and control points of the composite roof with weak interlayer in the deep gob-side roadway, the following separation joint control method was proposed: increasing the bearing capacity of coal pillars, reducing the development of the failure in roof and increasing the deformation coordination of roof with weak interlayer. The maximum separation of the roof is 10 mm according to on-site separation monitoring, indicating that this method can effectively control the separation of the roof with weak interlayers.

In view of the frequent occurrence of rockburst in the coal pillars of high-stress roadways in deep underground coal mines in China, the types and mechanisms of rockburst in coal pillars are studied by means of field investigation, theoretical analysis, numerical simulation and engineering test. A new method of preventing rockburst by releasing energy and modifying the coal pillars of high-stress roadways is put forward. Based on the method proposed, a series of research work such as the principle research, technical system design and underground industrial test are carried out. Based on the main force source types of coal pillar rockburst in roadways, combined with many typical cases of rockburst, the coal pillar rockburst in roadways in China is divided into three types: basic stress superposition type, additional stress induced type and self-creep instability type. The mechanical models and engineering criteria of the occurrence mechanism of coal pillar rockburst in roadways are established and deduced respectively, which reveals its occurrence mechanism. In this paper, a method of preventing rockburst by combining fracturing with grouting in high-stress roadway in deep mine is proposed. The principle of preventing rockburst is embodied in two aspects: “energy release” and “modification”. The underground industrial test shows that the crack initiation pressure of elastic core coal is about 40 MPa, and the overall maximum fracturing width is 19.5 m. The field monitoring proves that the method proposed can reduce the energy accumulation level of roadway coal pillar and increase the overall impact threshold of roadway coal pillar. A complete technical system of coal pillar energy release modification and erosion prevention in high stress roadways of deep underground coal mines is designed, including the “evaluation-inspection-check” method of impact risk of isolated coal body, the energy release technology of elastic nuclear hydraulic fracturing and the whole grouting reinforcement modification technology. The “vibration-stress-displacement” three-field monitoring equipment for the elastic nuclear fracturing of coal pillars in roadways and the PS-Z-A/B type inorganic two-component quick-setting integral grouting modified material have been developed.

Rock burst disaster has become a major safety problem in underground coal mining worldwide. Using the true triaxial electro-hydraulic servo loading test system, the stress-strain law, failure characteristics and acoustic emission activity law of coal-rock combination, deep coal body and shallow coal body with three different stress types are studied. The strength criterion relationship of deep and shallow coal bodies is established, the energy release characteristics of deep coal body are analyzed, and the instability mechanism of deep coal body is revealed. The results show that the coal samples with different stress types are affected by the stress environment and structural differences. The shallow coal samples of the roadway rib and the coal-rock combination samples of the roadway rib under high σ2 confining pressure all produce rapid stress drop after the peak stress, and the brittle failure and impact are strong. In the failure mechanism, the shallow coal sample of the roadway is mainly controlled by the tensile-shear coupling mechanism. The deep coal sample of the roadway is mainly controlled by the shear mechanism. The area near the constraint surface and the free surface of the coal-rock combination sample is controlled by the shear and tension-shear coupling mechanism respectively. Under the condition of same confining pressure, the shallow coal body of the roadway is more likely to be destroyed. Based on the source of the impact energy release of the roadway coal rib, the instability model of the coal body in the deep roadway is established, and the instability mechanism of the coal body in the deep roadway is revealed.

As the mining depth of major gold mines around the world increases, high-temperature surrounding rock transfers a significant amount of heat to the airflow in roadways, thereby significantly raising the air temperature. The use of insulating materials on roadway surfaces has proved to be an effective method for improving the thermal environment of underground workplaces. This study validates the functionality of pumping wet shotcrete with phase change materials (PWS-MPCM), previously developed for roadway support, using fluid dynamics numerical simulation to analyze the temperature distribution within the surrounding rock. The results show that PWS MPCM significantly impacts the temperature distribution within the surrounding rock and exhibits excellent thermal insulation and temperature control properties. This study demonstrates that PWS-MPCM can be a fundamental solution for mitigating heat hazards in deep gold mines. [ABSTRACT FROM AUTHOR]

This study aims to provide a comprehensive analysis of the impacts of high-intensity coal mining on vegetation in Liangbei Town, a typical deep coal mining area in central of China. Using Landsat remote sensing data from 2000 to 2023, processed by the Google Earth Engine (GEE) platform, the study calculates the Normalized Difference Vegetation Index (NDVI). Temporal and spatial distribution patterns of vegetation were assessed using LandTrendr algorithm, Sen's slope estimation, the Mann–Kendall test, the coefficient of variation, and the Hurst index. Vegetation growth dynamics were further analyzed through transfer matrix and intensity analysis frameworks. Driving factors influencing vegetation trends were evaluated using local climate data and surface deformation variables from SAR imagery. Temporal Dimension: From 2000 to 2023, the annual NDVI in Liangbei Township showed an upward trend with a growth rate of 0.0894 (10a)−1, peaking at 0.51 in 2020. Spatial Dimension: The NDVI distribution in Liangbei Township displayed a pattern of being lower in the center and higher around the edges, with values concentrated between 0.4 and 0.51, covering 50.34% of the total area. Trend of Change: Between 2000 and 2023, 83.28% of the area in Liangbei Township experienced significant improvement in the NDVI, with vegetation growth trends shifting primarily from slight to significant improvement, encompassing a total area of 10.98 km². This shift exhibited a marked tendency. Driving Factors: Deep mining in Liangbei Township is concentrated in the eastern part, with SAR imagery indicating a maximum surface subsidence of 0.26 m. As surface subsidence increases, the NDVI significantly decreases. The findings suggest that in the future, 91.13% of the vegetation in Liangbei Township will display an antipersistent change trend. The study offers critical insights into the interaction between mining activities and vegetation cover can serve as a reference for environmental evolution and management in similar mining areas. [ABSTRACT FROM AUTHOR]

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 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.)

With the continuous development of the mining industry and advancements in deep mining technology, mine environment optimization has become key to ensuring safety and improving the efficiency of mining. The high-temperature environment, particularly in deep mines, not only poses a serious threat to miners' health but also significantly reduces operational efficiency. These issues have been determined based on the current application status and development trends of mine cooling technology, including traditional mechanical and non-mechanical cooling technologies, as well as emerging roadway insulation materials and mine cooling clothing applications. By comparing the advantages and disadvantages of each technology, the main challenges related to the use of current mine cooling technologies are pointed out, including the low energy efficiency ratio, high cost, and difficult implementation. Finally, this paper looks forward to the future development directions of mine cooling technologies, emphasizing the importance of intelligent, energy-saving, and environment-improving comprehensive system management and, in turn, promoting the progress and application of mine environment optimization technology and supporting safe and efficient deep mining. [ABSTRACT FROM AUTHOR]

To study the deep-mine rock failure mechanism and the technical issue of ground pressure manifestation using the downward approach filling mining method in the deep ore bodies in the mining area of Songxian Shanjin, the research employs rapid modeling techniques using Rhino + Griddle + Flac³ to investigate the stress and displacement patterns of ore rock during 1-8 a of downward approach mining. The simulation results indicate that the minimum principal stress increases with depth, being greater near the bottom. The unmined stope acts as a temporary ore pillar, exhibiting significant stress concentration, and a stress relief zone forms in the filling body near the stope. The displacement in each level increases with mining time, with the maximum displacement at the stope roof appearing mainly in the middle of the roof. As the mine progresses deeper, the maximum displacement value shows an upward trend. [ABSTRACT FROM AUTHOR]

During the medium long-hole blasting process in deep steeply inclined thin ore bodies, the surrounding rock's compression force often causes issues such as "inadequate blasting" or "excessive blasting" during production practice. This leads to significant mining losses and ore dilution. Based on the mining technical conditions of a specific mine and using PFC 2D numerical simulation software to numerically simulate the medium long-hole blasting process in deep steeply inclined thin ore bodies, a quantitative analysis was performed on the impact of surrounding rock compression force on blasting effects in deep steeply inclined thin ore bodies. It was determined that the borehole diameter should be 65 mm and the blast spacing (resistance line) should be 1.6 m. Field applications showed that the blasting results were satisfactory with a low block rate, an ore dilution rate of 15%, a mining loss rate of 5%, and an explosive consumption of 0.6 kg/t. The numerical simulation results were consistent with field blasting effects, and the corresponding blasting parameters can guide on-site production [ABSTRACT FROM AUTHOR]

The 1 200 m roadway blasting and excavation construction in the return air shaft at Shaling Gold Mine is affected by complex working conditions such as ground stress, stratification, and mine water. These factors result in poor blast formation, long auxiliary operation time, and slow construction progress. To address these issues, the digital electronic detonator-detonating cord mixed initiation network perimeter formation control technology was adopted to optimize the original blasting scheme and conduct field experiments. The results of the field experiments showed that the optimized digital electronic detonator-detonating cord mixed initiation network and smooth blasting scheme significantly improved the blasting formation effect, reduced surrounding rock damage, increased the half-hole mark rate by 54.5 percentage points, decreased the over-excavation coefficient by 21.7%, shortened the operation time by 15%, and reduced the economic cost per cycle by 185.7 yuan. This achieved quality control of perimeter formation in roadways with complex working conditions and provided a reference for similar roadway blasting projects. [ABSTRACT FROM AUTHOR]

With the continuous extension of mining development systems, the mining depth of some mines domestically and abroad has reached below 1 000 m, and in a couple of years, some mines will exceed depths of 1 500 m or even 2 000 m. In the process of deep mining, due to the effects of geothermal gradient, heat release from large amounts of mechanical equipment and surrounding rock, and long-distance single-heading excavation operations, the operation environment temperature can reach above 40 °C. This severely restricts mining efficiency and jeopardizes the physical and mental health of workers. Therefore, high-temperature heat hazards are one of the main technical challenges that need to be addressed in deep mines. Through data collection and technical survey, it is summarized that deep mines at home and abroad face ventilation problems mainly in terms of poor air environment, insufficient total air volume, disordered ventilation networks, poor management of ventilation equipment and structures, and high costs. The main hazards caused by high-temperature environments to humans, equipment, surrounding rock, and support are identified. Based on this, conventional ventilation cooling and refrigeration cooling methods and proposals for key technical measures are summarized. The research findings provide technical references for controlling high-temperature heat hazards in deep mines. [ABSTRACT FROM AUTHOR]

With the ongoing depletion of surface and shallow mineral resources, future mining efforts must inevitably venture deeper. As mining depth increases, operations face a "three high and one disturbance" environment, severely affecting normal production activities. Therefore, pressure management has become an essential prerequisite for mine production. The study consolidates current research achievements in 3 areas, including basic theory, monitoring methods, and ground pressure management, to provide foundational guidance for practical mining operations. Basic theory explores the internal mechanical mechanisms of ground pressure activities through dynamic-static load combinations and temperature seepage stress multi-field coupling effects. Monitoring methods discuss the deployment of stress-strain monitoring systems and microseismic monitoring systems, where static stress-strain monitoring and dynamic real-time microseismic monitoring work in tandem to effectively monitor pressure activities during production. Pressure management measures cover pressure regulation methods and support systems, clarifying current issues in fundamental theories and prevention measures for deep mine pressure and guiding future research to promote intensive deep mining [ABSTRACT FROM AUTHOR]

This paper details the current research status and technical challenges of deep gold mine mining, discussing in detail theories of mining-induced rock mechanics, rock mass structure identification and rock mass quality classification, mine 3D engineering disaster modeling, study of deep mining design methods, deep stope blasting and caving technology, mining-induced ground pressure regulation and monitoring, self-supporting active pressure relief support technology, impact on surface rock displacement, ventilation and cooling technologies, intelligent mining, and ultra-deep vertical shaft construction. Prospects for future development in areas such as the development of non-explosive mining robots for gold mines, mining-induced rock mechanics, prevention and control of deep mining-induced ground pressure disasters, deep mine cooling technology, construction of ultra-deep vertical shafts, and continuous intelligent mining technology based on the equilibrium of mining-induced ground pressure have been proposed, providing a reference for systematic research on deep gold mine mining. [ABSTRACT FROM AUTHOR]

Copyright of China Mining Magazine is the property of China Mining Magazine Co., 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.)

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.)

The gradual depletion of shallow resources necessitates the imperative shift towards deep mining. In deep mining, dynamic disasters, such as rockburst, caused by high in-situ stress and other complex geological environments, have persistently posed a significant challenge to the safe and efficient extraction of deep minerals. Despite the longstanding occurrence of rockburst disasters, they have not been effectively resolved due to limitations in their occurrence mechanisms and monitoring methods. In this paper, the evaluation system and the prevention and control technology of rockburst were systematically summarized and concluded through literature research. The current research progress shows that there are many evaluation systems of rockburst, which can evaluate and predict the grade and tendency of rockburst disasters well. Regarding rockburst prevention and control systems, they can generally be classified into passive and active control technology based on the timing of disaster management and protective mechanisms. The overall planning concept was developed based on mining plan optimization and stress environment reconstruction, providing a new idea and method for rockburst prevention and control in deep mining of metal mines. Finally, taking the deep mining of Sanshandao Gold mine as the background, the advantages and effects of the unloading mining scheme in rockburst control and prevention under the integrated planning concept were verified, which provided an effective reference for the advanced intervention and active prevention and control of rockburst in deep mining of metal mines in the future. [ABSTRACT FROM AUTHOR]

To study the effect of temperature on the dynamic mechanical properties of marble, dynamic compres- sion tests, XRD, and SEM microscopic tests were conducted on marble samples at room temperature (25 °C) and after exposure to high temperatures (200 °C, 400 ℃, 600 °C, and 800 °C). The relationship between the dynamic mechani- cal properties of marble and temperature, as well as the microscopic damage mechanisms, were explored. The results show that the dynamic compressive stress-strain curves of marble after high-temperature exposure can be divided into 3 stages: elastic, yield, and failure. The peak stress and failure characteristics of marble exhibit a significant tempera- ture effect: as the temperature increases, the peak stress of marble gradually decreases, and the degree of fragmentation intensifies. The dynamic mechanical properties of marble are closely related to its mineral composition and crystal structure. Between 200 °C and 600 °C, micro-defects increase, and dolomite undergoes thermal decomposition and transformation. At 800 °C, mineral decomposition produces CO₂ gas and calcium hydroxide, and the crystal structure undergoes melting damage, leading to severe internal damage and increased plasticity, resulting in a substantial decline in macroscopic mechanical properties. [ABSTRACT FROM AUTHOR]

To quantify the heat released during the deep mining of gold mines and provide suggestions for heat hazard management, this study analyzed the variation of original rock temperature with depth and calculated the heat release from blasting, surrounding rock, and equipment. The results show that the geothermal gradient of the mining area is approximately 1.7 °C/100 m. At the 752 m level, the original rock temperature reaches 34.3 °C. During deep mining, the main heat sources in summer are heat release from electric power of mechanical equipment and air compression, accounting for 38.18% and 26.56% of the total heat, respectively. In winter, the primary heat sources are heat released from surrounding rocks and mechanical equipment, accounting for 38.74% and 24.81% of the total heat, respectively. With a ventilation rate of 67.9 m³/s, the overall environment during deep mining can be kept suitable. In cases of localized high temperatures, targeted cooling can be achieved by increasing ventilation. [ABSTRACT FROM AUTHOR]

Addressing issues such as low production capacity, high labor intensity, and frequent ground pressure manifestations in the chamber-based dry filling mining method at Jiapigou Gold Mine, this study conducted experimen- tal research on the lightweight energy-absorbing paste filling mining method. Given the characteristics of the deep steeply inclined thin ore bodies and mining technical conditions at Jiapigou Gold Mine, the original chamber for material extraction within the stope was eliminated, simplifying the extraction process and reducing the operation cycle time. The lightweight energy-absorbing paste possesses sufficient strength to effectively support the hanging wall and footwall of the stope, ensuring stope stability and enhancing operational safety. Field application results indicate that using this method, average stope production capacity reached 20. 66 t/d, an increase of 47.25%. The mining loss rate decreased from 12% to 3.5%, and the ore dilution rate dropped from 8.6% to 4.2%. The results are promising and provide a valuable reference for similar mines. [ABSTRACT FROM AUTHOR]

Traditional research believes that the filling body can effectively control stress concentration while ignoring the problems of unknown stability and the complex and changeable stress distribution of the filling body-surrounding rock combination under high-stress conditions. Current monitoring data processing methods cannot fully consider the complexity of monitoring objects, the diversity of monitoring methods, and the dynamics of monitoring data. To solve this problem, this paper proposes a phase space reconstruction and stability prediction method to process heterogeneous information of backfill-surrounding rock combinations. The three-dimensional monitoring system of a large-area filling body-surrounding rock combination in Longshou Mine was constructed by using drilling stress, multipoint displacement meter, and inclinometer. Varied information, such as the stress and displacement of the filling body-surrounding rock combination, was continuously obtained. Combined with the average mutual information method and the false nearest neighbor point method, the phase space of the heterogeneous information of the filling body-surrounding rock combination was then constructed. In this paper, the distance between the phase point and its nearest point was used as the index evaluation distance to evaluate the stability of the filling body-surrounding rock combination. The evaluated distances (ED) revealed a high sensitivity to the stability of the filling body-surrounding rock combination. The new method was then applied to calculate the time series of historically ED for 12 measuring points located at Longshou Mine. The moments of mutation in these time series were at least 3 months ahead of the roadway return dates. In the ED prediction experiments, the autoregressive integrated moving average model showed a higher prediction accuracy than the deep learning models (long short-term memory and Transformer). Furthermore, the root-mean-square error distribution of the prediction results peaked at 0.26, thus outperforming the no-prediction method in 70% of the cases. [ABSTRACT FROM AUTHOR]

The overall stability of cemented tailings backfill (CTB) false roof, as an important support structure in the quarry, is of great significance for realizing the safe recovery of the ore body. This paper aims at the practical problem of ore body mining under the condition of deep broken rock mass. By analyzing the typical process characteristics of underhand cut-and-fill mining method, the dangerous mechanical state of CTB false roof is determined, and the CTB false roof strength model based on the maximum tensile stress failure criterion and deep mining coefficient is established. Based on the measured load value of CTB false roof, the minimum required strength of CTB false roof is obtained. Through the performance tests of CTB under different proportioning schemes, the mechanical strength of CTB false roof (UTS：0.43 MPa, UCS：6.22 MPa) is designed，the proportioning parameters of CTB with ''high strength, high fluidity, quick setting and low cost'' are put forward. Finally, based on FLAC3D numerical simulation and field monitoring, the stability of CTB false roof with recommended ratio parameters is analyzed. The results show that the CTB false roof has not been violently displaced and destabilized in the process of service ore body mining, has good strength reserve, and is able to provide a safe workspace for mining, verifies the reliability and reasonableness of the CTB false roof proportioning parameter, and provides a new way for the study of false roof stability.

The Dongsheng Coalfield in Ordos is a Jurassic coal bearing formation, and the 2-2 and 3-1 coal seams in many deep mining areas can be mined in the whole area, and the spacing of coal seams is small. This paper takes Yingpanhao Coal Mine as a geological prototype, and constructs a numerical model of the research area through FLAC3D and UDEC numerical simulation software to study the surface movement deformation and the evolution law of stress field caused by mining coal seams 2-2 and 3-1. The results show that repeated mining in multiple coal seams will cause the central projection of the subsidence basin to move toward the direction of lower coal seam, and then approach the central projection of the initial mining of the upper coal seam, and ultimately cross it; after the two coal seams were continuously mined, the maximum subsidence value of the surface is less than the sum of the maximum subsidence values caused by mining the two coal seams separately, and the subsidence coefficient of the coal seam repeated mining is less than the initial mining subsidence coefficient; coal pillar dislocation is closely related to surface movement parameters, the staggered coefficient is related to the surface subsidence coefficient, horizontal movement coefficient, and the tangent of the main influencing angle in a logarithmic normal function, concave parabolic function, and convex parabolic function, respectively; as common factors, pillar staggered distance and width-depth ratio have coupling effects on the ratio of characteristic parameters of primary mining and repeated mining in coal seam; in addition, with the increase of pillar staggered distance, the surface subsidence basin area decreases first and then increases, and the contours of horizontal movement near the basin evolve from ellipse to shuttle; the optimal staggered distance of multi-coal seam mining in this study area is 30 m based on the empirical formula of pressure relief distance, the surface damage degree and the relief effect of staggered mining.

In the process of deep mining, the temperature of mine water is significantly higher than that of shallow coal seams. The erosion of high-temperature hydrothermal fluids affects the physical and chemical characteristics of coal, which in turn affects its spontaneous combustion process. To study the spontaneous combustion characteristics and influencing mechanisms of coal under the influence of hydrothermal erosion in deep mining, through low-field nuclear magnetic resonance, molecular dynamics simulation, mechanical test and C600 trace heat experiment, the influence of hydrothermal erosion on coal porosity, pore size distribution, mechanical strength and oxidation heat characteristic parameters was analyzed. Combined with correlation analysis, the correlation between various parameters was quantitatively described. The study results show that under the dual influence of thermal stress and swelling, the internal pore structure of hydrothermal eroded coal changes significantly. There is a significant positive correlation between hydrothermal temperature and total porosity of coal, and the correlation coefficient is 0.97. With the increase of hydrothermal temperature, the total porosity of coal increases from 0.24% to 1.35%, the proportion of micropores decreases from more than 69% to less than 60%, and the proportion of mesopores and macropores increases. Coal body pore size significantly affects the oxygen diffusion coefficient, which increases exponentially with a linear increase in coal body pore size. Under the influence of hydrothermal erosion, the development of coal pores and the dissolution of some organic matter significantly reduce the mechanical strength of coal. From raw coal to 80 ℃ hydrothermal eroded coal, the average compressive strength decreases from 23 MPa to 11.6 MPa, which is reduced by 50%. Compared with raw coal, the heat release intensity of hydrothermal erosion coal is higher and the heat release is greater. The heat release of TH40, TH50, TH60, TH70 and TH80 increase by 12.61%, 16.63%, 17.32%, 19.36% and 25.02%, respectively. The correlation coefficient between hydrothermal temperature and coal oxidation heat release is 0.92. Hydrothermal erosion significantly affects the porosity and oxidation process of coal. As the hydrothermal temperature increases, the porosity of the coal body increases, the mechanical strength weakens, the oxygen consumption and oxidation rate of the oxidation process accelerate, and the heat release increases. Hydrothermal erosion coal has a higher risk of spontaneous combustion, and the higher the hydrothermal temperature is, the greater the risk is.

Accurate determination of gas content in deep coal mine is the premise for the prevention and control of gas disaster, as well as the efficient development and utilization of coalbed methane. Traditional coring technology of coal seam is generally open-ended and requires to obtain the amount of gas loss during the coring process by using estimation methods, making it difficult to ensure the accuracy and validity of the in-situ parameters of coalbed methane. Based on the academic idea of “in-site condition-maintaining coring”, the in-situ pressure- and gas-maintaining coring technology for deep coal seam was proposed, and the in-situ pressure- and gas-maintaining corer for deep coal seam was developed. The strength verification for corer outer tube, pressure-maintaining chamber and key weak parts were conducted based on three-dimensional numerical simulation. Meanwhile, the pressure-maintaining capacity of controller was measured and analysed relied on the self-developed pressure-maintaining coring laboratory simulation test platform, and the reliability of corer was verified through field tests in coal mine. The results shown that, the self-developed corer had the advantages of strong pressure-maintaining capacity, long pressure-maintaining time and stable anti-disturbance performance. The equivalent stress of the corer under internal fluid pressure of 20 MPa and torque of 1000 N·m was 121.1 MPa, which was much smaller than the yield strength of the material and met the strength design requirements. The equivalent stress of corer under the pressure of 20 MPa was 63.9 MPa, which met the strength design requirements. The corer can operate continuously and stably at the pressure of 19.4 MPa, which met the demand for gas testing in most of deep coal mines. The field test shown that, the pressure-maintaining controller of the pressure- and gas-maintaining corer closed well, with 100% of coring rate in the field. The research provides a theoretical, technical and equipment foundation for the accurate determination of gas content in deep coal seams, which is of great significance for the prevention and control of coal mine gas disasters and the exploration and development of coalbed methane.

The construction of 14 large-scale coal bases and 89 demonstration bases for the comprehensive utilization of bulk solid waste in China marks that the utilization of bulk solid waste in mining areas has been incorporated into the national strategic development layout. The long-term high-intensity development and utilization of coal resources has caused the near depletion of shallow-buried coal seam resources in mining areas, and the large-scale solid waste accumulation and surface subsidence of coal power and chemical bases has become a problem restricting the green, low-carbon and high-quality development of mining areas. Co-operative utilization of bulk coal-based solid waste and green filling is an effective way to liberate the “three down and one up” pressed coal, extend the service life of mines, and realize the harmless, resourceful, and large-scale “three” utilization of solid waste. Based on the types and production of coal-based solid waste in Shanxi Province, the “East China Energy Granary” Anhui Lianghuai Base and Ningdong Energy and Chemical Base, it elaborates in detail the harmless disposal of coal-based solid waste through heavy metal adsorption and desorption and complexation passivation technology with coal gangue, fly ash, furnace slag, gasification slag and desulphurization gypsum as the main materials, listing the classification and application of coal-based solid waste, and the application of coal gangue, fly ash, furnace slag, gasification slag and desulphurization gypsum as the main materials. List the ways of resource utilization of coal-based solid waste classified and applied to low calorific value coal-based solid waste for power generation, preparation of building materials such as cement, bricks and tiles, etc. Comparatively analyze the ways of reclamation and backfilling of coal mining subsidence area and downhole filling and large-scale utilization of coal-based solid waste, highlighting the superiority of downhole filling of coal-based solid waste. Based on the deep coal resources of coal electrification bases, the theory and key technologies of green filling mining are proposed, including the synergistic technology of deep coal gangue source reduction and mining and filling, the technology of efficient preparation and deep underground transportation of filling materials, and the deep multi-field coupling mechanism of coal-based solid waste filling materials, and the technological principles and methods of the whole process of deep filling mining of multi-source coal-based solid waste from the source, process to the end are investigated to solve the technical problems of deep underground filling of mining areas. The technical problems of filling are solved. According to the geological conditions and filling purposes of Renjiazhuang Coal Mine in Ningdong Base, Huoerxinhe Coal Mine in Shanxi Province and Huaibei Mining Area, the key technologies of low-level filling by overdrilling, multi-separation layer stepped grouting under the conditions of atypical characteristics of key layers and synergistic utilization of coal-based solid wastes have been proposed, which comprehensively combine the advantages of disposal and utilization of solid wastes from mines, development and utilization of deep coal resources, control of subsidence of the ground surface, and ecological environment protection, and form a comprehensive plan for the disposal and utilization of bulk solid wastes from coal power and chemical bases. Coal power and chemical base bulk solid waste synergistic utilization and green mining mode, providing reference for high quality coal mining and low damage to the environment.

With the continuous increase of coal mining depth, the occurrence and prevention of deep rockburst in China have become normalized. In order to improve the effectiveness of deep rockburst prevention and control technology, starting from the technical difficulties of deep rockburst prevention and control in on-site engineering, combined with practical data statistics of disaster prevention and control engineering, this study demonstrates that the deep rockburst in China is due to its high geological stress and large range of human mining disturbance. The stress recovery of surrounding rock is fast after rock stress unloading during the disaster prevention and control process. The low effectiveness of rockburst prevention and control can be attributed to the new requirements of “three highs and one low” prevention and control technology in deep mining compared to that in shallow mining, including high-strength large-sized drilling to relieve pressure, in order to solve the collapse prone problem of thick and hard coal seams; small spacing high-density drilling to solve the problem of disconnected pressure relief range in drilling; multiple rounds of repeated high-frequency construction to solve the problem of rapid stress recovery after unloading pressure in deep coal seams; and the mining face is advancing at a low speed to solve the problem of high mining disturbance intensity. In response to the new requirements of “three highs and one low” prevention and control mode for deep rockburst, in order to further improve the safety and reliability of rockburst prevention and control, and based on the limitations of optimizing development and mining deployment for conventional source rockburst prevention and control, this paper proposes the technology of actively regulating the structure and load of overlying rock layers in the deep rockburst prevention and control areas, and presents some further scientific problems that need to be solved. Against the background of several typical rockburst accidents in recent years with the problem of “missed targets” in the prevention and control plans, a local targeted prevention and control technology for deep rockburst mining space has been developed, and the scientific challenges that need to be solved in the future have been pointed out. Against the background of the difficulty in evaluating safety issues after the implementation of coal mine rockburst prevention and control measures, a deep rockburst prevention and control unloading standard evaluation technology is proposed, and the scientific difficulties that need to be solved in the future are pointed out. The coal industry vigorously promotes intelligent mining, but the disaster control still relies on manual labor and personnel to operate in a high-risk environment. This paper also explores the emerging research direction and scientific challenges of intelligent mining and intelligent prevention and control of deep rockburst. Finally, it is objectively pointed out that the prevention and control of rockburst is not purely a theoretical and technical issue, and the human understanding of technical issues is also one of the important reasons for rockburst accidents. Combining with the on-site engineering practice, this paper discusses the concept and mechanism of rockburst, whether rockburst can be predicted, whether rockburst can be prevented and controlled, and how to deal with rockburst mines and other industry focused technical issues. It is pointed out that the problem of rockburst engineering is a struggle between humans and nature, which requires practitioners to objectively understand, objectively accept, and conduct in-depth research. The current achievement is of significance.

To solve the problem of serious deformation and difficult support of the roadway under deep high stress, the research centers on the 710 m horizontal roadway in Jiaojia Gold Mine, establishes Flac³D numerical model to simulate and analyze the disturbance response law of the surrounding rock during the roadway excavation process. The results show that due to the mining disturbance of the roadway, the stress around the roadway is released. Thus, the stress is redistributed, with the stress around the roadway concentrated, and the stress peaks mainly occurring in the roof, the arch shoulder, and the upper and lower sides of the side walls, so the support should be strengthened in the roof, the arch shoulder, and the upper and lower sides of the side walls; within a range twice the width of the roadway is the focus area for support; after excavation, surrounding rock mass will experience shear and tensile failure. By analyzing the evolution of deformation and stress distribution in the roadway, the process of deformation failure of surrounding rock during excavation is revealed, providing a scientific basis for support parameter design and support timing. [ABSTRACT FROM AUTHOR]

To ensure the sustainable development of energy supply, there is a continuous increase in demand for deep coal mining, making safe and efficient extraction a crucial area of research. However, with the increasing depth, rising ground temperatures pose new challenges for safe and sustainable mining operations. Among these challenges, coal and gas outburst dynamic hazards stand out as significant issues. Therefore, it is necessary to assess the impact of temperature variations on coal and gas outburst disaster prevention and control. To investigate this effect, we conducted an analysis based on outburst-triggering mechanisms and adsorption–desorption processes. Temperature was considered as the primary controlled variable, while gas expansion energy served as the criterion for assessing outburst hazards. Kilometer-deep coal samples were selected for measurement, focusing on indicators such as Langmuir adsorption constants (a,b), gas content (Q), gas pressure (P) and drilling cutting desorption indices (K1, Δh2). The results indicate that, under the same gas pressure, there is a slight decreasing trend in gas expansion energy with increasing temperature, although the overall change is minimal. Hence, the sole influence of temperature on the gas's ability to perform work during outbursts is limited. Temperature exerts varying degrees of influence on gas parameters such as gas content and drill cutting desorption indices. The fluctuation amplitudes of these indicators range from large to small in the following order: Δh2 > ΔP > Q > K1 > P. Additionally, their correlation with gas expansion energy decreases in the following order: P > Q > Δh2 > K1 > ΔP. Thus, the influence of temperature on the indicators used in various prediction methods exhibits inconsistency, emphasizing the importance of considering temperature effects on predicted values. Gas pressure emerges as the optimal indicator for outburst determination, while gas content and drill cutting desorption indices are preferable as predictive indicators. These results will provide valuable references for the sustainable and safe development, risk assessment and prediction of deep coal mining. [ABSTRACT FROM AUTHOR]

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With the gradual extension of mining operations into deeper levels, minor rock burst phenomena have emerged, posing risks of instability in mining pillars and roof caving induced by rock bursts within the production area. Based on the actual geological conditions of deep ore bodies and surrounding rocks in Sanshandao Gold Mine, a new generation of microseismic monitoring system has been developed, in order to establish a mine early warning system. This system can effectively monitor faint seismic signals associated with the instability of mining pillars and roof caving in the mining area, analyze microseismic waveforms, and detect occurrences of rock burst events, providing basis for the safe mining of deep rock mass. [ABSTRACT FROM AUTHOR]

The strong mine pressure disaster easily induced by the high stress concentration area of deep coal seam bifurcation and merging area (CSBMA). Zhangshuanglou Coal Mine was selected as the research site. Theoretical analysis, physical and numerical simulation and field measurement was adopted to study the evolution law and control technology of mining-induced stress in the deep CSBMA. The main conclusions are as follows: (1) from the bifurcation area to the merging area, the peak value of the front abutment pressure decreases first and then increases slightly to a stable evolution law with the gradual decrease of the coal seam spacing. From the merging area to the bifurcation area is the opposite. (2) The coal seam spacing of the bifurcation area is 7.5–25 m, which is the area where the peak value of the front abutment pressure increases. The maximum peak value is located at the junction of the normal area and the bifurcation area, and the stress concentration coefficient is about 2.1. (3) After the control technology of coal seam water injection softening is adopted for the high stress concentration area, the maximum peak stress concentration coefficient is reduced to about 1.6, which effectively reduces the stress concentration degree. The evolution law of mining-induced stress in the deep CSBMA provides guidance for the prevention and control area of strong mine pressure disaster in this area, and ensures the safe mining of working face. [ABSTRACT FROM AUTHOR]

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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 Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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 depth of coal mining in the central and eastern China is increasing, the ground pressure is high, the roadway deformation and burst risk is great. Gob-side entry with slender gate pillar (GESGP) is constantly adopted to improve surrounding rock environment. In order to grasp ground pressure behavior of the gob-side entry and develop targeted surrounding rock control measures, field observation and numerical simulation have been carried out against a case of GESGP of 3 m pillar in a ultra thick coal seam of a 800 m cover depth. The results show that: ① Fragmentation and deformation of surrounding rock on the coal pillar side are larger than the other side. Fragmentation and deformation of pillar at the gob side is larger than the other; Although the buried depth is great, the gob is settled and a large amount of overburden load is sustained by it, so the stress is sufficiently transferred to the deep rocks; ② The deformation of the gob-side entry is asymmetrical, the roof sags more on the pillar side than the other, pillar rib top and solid coal side rid middle are greater with deformation occurring mostly at shallow part; ③ Gob is the “escape” passage for entry deformation which is good for slow release of deformation energy and reduction of burst; ④ The range of the pressure relief area is expanded from triangle before excavation to parallelogram after excavation, also the location of the stress concentration area is shifted to the upper right of the entry; ⑤ Interface of the first/second shear failure planes on the pillar and the high stress zone on the upper right of the entry are the key targeted control zones. The surrounding rock control system was put forward that coal pillar reinforcement based on multiple plastic zone development cycles and precise destress of high stress zone. The research can provide research foundation and scientific basis for the adjacent panels and other similar deep and inclined extra-thick coal seams.