Abstract:In order to develop a new type of green high-performance mine grouting material,ordinary Portland cement(OPC)and fly ash(FA)were used as raw materials,and fly ash-cement-based grouting material(FCGM)was modified by introducing nano-silica(NS)to construct a high-performance composite grouting material system.The effects of NS on the properties,mechanical properties and evolu-tion of hydration products of FCGM slurry were systematically studied by different macroscopic and microscopic test methods.Through the grouting consolidation test of sandstone aggregate,the influence of NS modification on the macroscopic mechanical behavior and acoustic emission(AE)damage evolution characteristics of the cement was compared and analyzed.The results show that the content of NS has a significant effect on FCGM,which can significantly improve the compressive strength of FCGM,shorten the setting time,re-duce the bleeding rate and reduce the fluidity.Especially when the NS content is 1％,the compressive strength of FCGM is the best,and the compressive strength of 3 d and 90 d is 10.58％and 98.00％higher than that of the control group N1,respectively.Microscopic charac-terization(XRD,FTIR,TG-DTG and SEM)confirmed that NS could effectively promote the hydration process of FCGM and signific-antly optimize the internal microstructure of the stone body.The grouting reinforcement test of sandstone shows that the 28 d uniaxial compressive strength of 1％NS modified FCGM consolidated body is increased by 90.8％,and the crack propagation and pore develop-ment are effectively inhibited,and its multifractal characteristics are improved.The AE monitoring further reveals the NS enhancement mechanism.The damage precursor signal of the modified cement is earlier and more active,which shows the synchronous rapid growth of high amplitude ringing count and cumulative energy,and finally changes its macroscopic failure mode from tension-shear composite to tension-dominant.By establishing the multi-scale correlation between material modification,microstructure,macroscopic mechanics and damage evolution,the comprehensive mechanism of NS reinforced FCGM is clarified,which provides theoretical basis and data support for the development of high-performance deep grouting materials and the prediction of their engineering failure behavior.

Abstract:Geological assurance technology constitutes a fundamental basis for achieving safe,efficient,and environmentally sustainable coal mining,and serves as a critical pillar supporting the intelligent development of coal mines.Transparent geological assurance systems enable comprehensive and dynamic perception of mine geological conditions,facilitating the end-to-end application of geological informa-tion-from acquisition,modeling,and analysis to decision-making-and have thus become an integral component of intelligent coal mine op-erations.The system is centered on multi-source spatiotemporal information perception and relies on high-resolution three-dimensional(3-D)seismic exploration,directional long-distance drilling equipment,integrated borehole-based advanced geophysical prospecting,and real-time seismic monitoring during mining and tunneling to dynamically identify key geological parameters such as coal-rock undulation,structural anomalies,hydrogeological hazards,and roof-floor stability.Multi-source heterogeneous geological data are integrated through coordinate registration,cross-validation,and joint inversion methods,while kriging interpolation,radial basis functions,and stochastic simulation algorithms are employed to achieve continuous and uncertainty-quantified representations of geological geometries and prop-erty fields,thereby constructing a high-precision 3-D geological model of the entire mine for continuous spatial characterization.On this basis,a"mining-geology"digital twin couples dynamic engineering data,such as mining equipment operation and support activities-with the 3-D geological model.Through virtual-real mapping technology,the system enables real-time feedback of geological bodies and their associated attributes to mining operations and,combined with multi-field coupled disaster mechanism models,analyzes the perturbation ef-fects of mining activities on geological structures,providing early warning and risk-informed decision support for coal mine production.Meanwhile,the system can quantify complex geological conditions and achieve high-frequency,real-time dynamic updates of geological information adapted to mining processes.Empirical applications have demonstrated that transparent geological assurance systems effect-ively support three-dimensional forecasting and management of concealed hazard factors,realizing a"Transparent Geology+"approach to mine disaster prevention and control,and supporting mining geological navigation applications such as shearer cutting,roadway excava-tion layouts,and support optimization.In summary,transparent geological assurance technology has achieved notable advancements;however,due to the complexity of mine geological conditions,challenges remain in the degree of geological information perception,the construction of adaptive geological analysis models,and the intelligent integration of equipment and models.Consequently,the system currently suffers from low model update efficiency and weak coordination capabilities between equipment and models.In the future,re-search should continue to advance across four key dimensions:the information perception layer,the model twin layer,the intelligent cog-nition layer,and the collaborative control layer.It should focus on high-precision multi-source information detection and fusion,intelli-gent evolution of digital twins,intelligent analysis technologies based on geological vertical large models,and integrated applications for full-mine production systems and equipment,thereby providing sustained theoretical support and technological pathways for intelligent and transparent geological assurance in coal mining.

Abstract:Intelligent roadway excavation is a key component in achieving the construction goals of smart coal mines.This paper elucid-ates the connotation of intelligent roadway excavation and,through an analysis of the characteristics and current development of rapid ex-cavation systems-including tunnel boring machine,bolter-miners,continuous miners,and integrated excavation-bolting machines-provides an in-depth examination of the critical technologies required to accelerate its development.These technologies encompass pre-cise equipment localisation,directional excavation,autonomous cross-section cutting and shaping,intelligent ground support,collaborat-ive control of equipment fleets,fault and safety early-warning for working-face equipment,geological condition perception,and intelli-gent working-face management and control.To address the requirements for equipment localisation,environmental perception,intelligent control,and decision-making in complex underground conditions,this work proposes cooperative-target-based visual localisation,"vision+"multi-source fusion integrated localisation,and targetless visual localisation techniques oriented towards roadway environmental features.In addition,visual+deep-learning-based methods for roadway cross-section fracture detection and roadway geometric reconstruction are developed,thereby enhancing the autonomous navigation and environmental perception capabilities of underground excavation equipment.Technologies for directional excavation and deviation correction,trajectory planning and cutting control,virtual-teaching-based memory cutting,bolt-hole recognition,multi-boom coordinated support control,and equipment-fleet collision early warning are proposed.These advances address the key control challenges in the excavation process,including difficulties in accurately regulating equipment pose,dy-namically planning cutting trajectories,ensuring coordination during support operations,and avoiding spatial interference among multiple machines,thereby enabling adaptive control of both excavation and support.By integrating digital twin technology into cutting control,collision detection and early warning,and collaborative control decision-making,a digital twin-driven intelligent management and control system for tunneling faces has been constructed,achieving real-time mapping between physical entities and virtual models,collaborative decision-making among equipment groups,fault diagnosis of key equipment parts,visual management of the operation process,and risk prediction.A development framework and research directions for intelligent roadway excavation technology are proposed,including equipment positioning based on multi-modal information fusion,intelligent control technologies for complex operating conditions,AI-driven virtual-physical collaborative intelligence for the working face,and digital-twin-driven virtual commissioning techniques.These ad-vancements aim to achieve highly automated,unmanned,and intelligent rapid excavation of roadways.

Abstract:The permeability coefficient of coal seams serves as a crucial indicator for evaluating the difficulty of gas extraction,the effect-iveness of pressure relief in protective layers to enhance permeability,and the severity of coal and gas outburst hazards.This paper briefly reviews the development of coal seam permeability coefficient determination methods,focusing on the research progress and respective characteristics of laboratory methods,radial flow methods,gas pressure recovery curve methods,and gas injection methods.Analysis in-dicates that laboratory methods offer advantages such as simplicity and low cost,but struggle to replicate underground conditions per-fectly;they may serve as important supplementary tools for field measurements in the future.The radial flow method,though widely ap-plied in the field,suffers from cumbersome calculation steps and discontinuous data values.Despite various optimization strategies pro-posed by scholars,no unified calculation standard has been established.The gas pressure recovery curve method offers strong in-situ test-ing capabilities and intuitive data interpretation,but it is significantly affected by plugging quality and pressure measurement accuracy,making it difficult to accurately capture the mid-term radial flow slope segment.The gas injection method demonstrates promising poten-tial in complex seepage coal seams,offering a viable approach for anisotropic permeability determination.However,its field measurement process is complex,and its on-site testing accuracy and data stability are limited.Future research on coal seam permeability coefficient de-termination should focus on several key areas:developing unified theoretical models that integrate multi-field coupling and multi-scale analysis;establishing industry standards and computational specifications for the radial flow method;enhancing the accuracy of pressure recovery curve identification and analysis;optimizing gas injection medium selection and test point layout;and improving field monitor-ing precision and automation levels.

Abstract:In the field of intelligent coal-gangue sorting,the density prediction of materials with wide thickness and density ranges is signi-ficantly challenged by the combined effects of dual-energy X-ray transmission physics,data fusion strategies,and complex material com-position,leading to high prediction difficulty and low accuracy.These issues severely hinder the development of intelligent photoelectric sorting technologies for coal-gangue and the quality-based classification and utilization of coal.To mitigate the impacts of these factors and improve the density prediction accuracy of coal and gangue,a prediction model based on virtual thickness images and an improved density formula is proposed.This model employs variable-window nonlinear smoothing filtering to reduce the impact of gangue inclusion,uses depth camera data as a thickness reference to calibrate low-energy image grayscale values,and constructs virtual thickness images that achieve pixel-level alignment with dual-energy X-ray images.The limitations of applying a unified density calculation formula are analyzed,and traditional density calculation formulas are improved based on the variation patterns of coal/gangue results across different density levels,establishing a density prediction model suitable for coal and gangue.Additionally,the introduction of boundary constraints further enhances the model's prediction accuracy.Through comparative testing with various algorithms on coal-gangue datasets of differ-ent density levels and thickness ranges,the performance of the proposed model is comprehensively evaluated.Experimental results demon-strate that the model accurately predicts coal and gangue densities within wide thickness-density ranges.For materials with densities of 1.30-1.80 g/cm3(mean thickness range:5-100 mm),the mean absolute error(MAE)and error variance(E-Var)are as low as 0.053 9 and 0.000 9,respectively.For materials with densities＞1.80 g/cm3(mean thickness range:5-100 mm),the MAE and E-Var are 0.210 6 and 0.033 2,re-spectively.Compared to the P-value method,transmission formula method,Archimedes principle method,and mass-volume ratio method,the proposed model maintains higher accuracy and stability while achieving multi-target synchronous measurements.In addition,high-ac-curacy electron density images were obtained,providing valuable data for subsequent key processes such as component analysis,calcula-tion of mass centroid,and assessment of material distribution.

Abstract:The construction of intelligent mines is driving the transformation of coal mine disaster prevention and control toward intelli-gent development,under which the prevention and control of coal and gas outburst disasters has become a critical challenge that urgently needs to be addressed in deep mining conditions.However,the existing coal and gas outburst prevention and control system still has prob-lems such as insufficient system integrity,broken prevention and control chains,and limited level of intelligence,making it difficult to achieve advanced and precise risk prevention and control.This article aims to construct a theoretical framework for the intelligent dual pre-vention mechanism of coal and gas outbursts,clarify its research boundaries,systematically review its research progress,thereby provid-ing theoretical support for the establishment of an intelligent coal and gas outburst prevention and control system.This article is based on the theory of dual prevention mechanism,taking coal and gas outburst disasters as the research object.Using a combination of literature analysis and systematic induction,it systematically sorts out and summarizes the intelligent dual prevention mechanism for coal and gas outbursts from five aspects:risk identification,assessment,prediction,warning and control.It summarizes the current research status,con-tributions and problems,and proposes future research priorities and directions.The results indicate that:The intelligent dual prevention mechanism for coal and gas outbursts covers risk identification,assessment,prediction,warning and control,as well as hazard classifica-tion and grading,investigation,treatment and acceptance,forming a systematic framework for disaster prevention and control.In terms of research contributions,intelligent identification has achieved automatic extraction of unstructured data and multi factor coupling analysis,intelligent assessment has constructed a dual driving paradigm of multi-attribute decision-making and machine learning,intelligent predic-tion has promoted the evolution from single point perception to multi-source fusion,intelligent warning has established a three-layer sys-tem of"real-time assessment-advanced prediction-precursor monitoring",and intelligent control has promoted the development of system integration,collaborative intelligence,and closed-loop control.In terms of research issues,the current intelligent identification system is not yet mature,the intelligent assessment model is fragmented and lacks generalization ability,the intelligent prediction has shallow data fusion and real-time deployment difficulties,the systematic exploration of intelligent warning is insufficient,the closed-loop efficiency of intelligent control is limited,resulting in weak coordination of the entire chain for prevention and control.Future research should establish an intelligent dual prevention system for coal and gas outbursts,deepen the fusion of multi-source data,qualitative quantitative transforma-tion of indicators,and unified real-time and periodic risks in identification,develop multi-level fusion frameworks and small sample,trans-fer learning methods in assessment,break through the difficulties of mechanism data fusion and model deployment in prediction,improve dynamic warning rules,multi device linkage and control response mechanisms in early warning,establish adaptive,collaborative intelli-gence and closed-loop mechanisms for control,and ultimately achieve full chain closed-loop intelligent prevention and control of coal and gas outburst disasters.

Abstract:In order to alleviate the problems of restoration success rate and ecosystem resilience under the condition of water shortage in the dump area in western China,the Zhunneng Heidaigou open-pit mine was selected as the study area,and different soil layer reconstruc-tion methods(three-layer structure and mixed structure)were used in the dump site,and different microbial combinations(AM,DSE,AM+DSE,CK)were combined for ecological reconstruction to study the water retention,water culvertability,and spatial distribution of water and salt in the reconstructed soil layer.Effects of microorganisms on plant growth and water use strategies.The results show that the ground penetrating radar verifies the physical characteristics of the three-layer structure and the mixed structure,the soil moisture of the three-layer structure is distributed in layers,the surface loess layer(ecological layer)increases with depth,the middle coarse sandstone lay-er(culvert layer)has a balanced water distribution and the moisture content reaches 12％,the bottom sandy clay layer(aquifer)has the function of blocking water infiltration,and there is no spatial difference in the water distribution of the mixed structure.The water reten-tion capacity of the three-layer structure treatment increased by 43.1％,and significantly increased the water absorption of 50-100 cm soil layer,thereby promoting the water utilization of plant roots,and the utilization efficiency reached 71.1％.Compared with CK,the water use efficiency of alfalfa was increased by 42.7％and the coverage was increased by 1.2 times.Therefore,the combination of three-layer structure and AM+DSE treatment has significant ecological restoration potential in the arid and semi-arid mining areas in western China,and this study provides new ideas and technical support for the ecological restoration of mining areas,which is conducive to the sustain-able development of mining areas in western China.

Abstract:Gob-side entry retaining with roof cutting is an important technique for achieving safe and efficient deep coal mining.However,under the combined effects of primary roadway excavation and secondary intensive mining-induced disturbances,severe surrounding rock deformation often occurs,with floor heave becoming a prominent problem.To clarify the stress transfer mechanism between the overlying strata and the floor during gob-side entry retaining,as well as the fracture evolution behavior of floor rock under variable loading rates,similarity simulation tests and uniaxial variable-rate loading experiments were conducted.The floor stress response and the mechanical be-havior,acoustic emission(AE)characteristics,and fractal features of sandstone under different loading rates were systematically analyzed.The similarity simulation results indicate that the floor surface experiences instantaneous unloading after roadway excavation.With the ad-vancement of the working face and periodic roof caving,the accumulation and compaction of caved gangue lead to stress recovery in the floor.After the overlying strata structure becomes stable,variations in floor stress gradually diminish,and the system enters a quasi-static equilibrium stage.Based on this stress evolution background,variable-rate loading experiments reveal that the loading rate has a signific-ant influence on the fracture mode and mechanical response of sandstone.Under rapid loading,high strain rates promote concentrated crack initiation and rapid coalescence,accompanied by intense energy release,resulting in typical brittle failure.When quasi-static loading is introduced at an earlier stage,cracks initiate at multiple locations and propagate slowly,the pre-peak nonlinear stage is prolonged,brit-tleness is reduced,and ductility is enhanced.Under fully quasi-static loading,damage accumulation is most sufficient,and the fracture pro-cess exhibits a progressive failure mode.AE results show that rapid loading induces sudden and highly concentrated AE activity,with sharp pre-peak increases in AE counts and energy,leading to an extremely short warning window.As the loading rate decreases,crack propagation is restrained,AE events become continuously active,and high-energy release persists even after peak stress.Multifractal ana-lysis demonstrates that the AE fractal spectra exhibit a bell-shaped distribution,which initially broadens and then converges with increas-ing stress.Rapid loading or late-stage rate reduction leads to left-skewed spectra with enhanced burst characteristics,whereas lower load-ing rates or early-stage rate reduction produce more symmetric spectra,indicating progressive crack development.Early-warning indicat-ors constructed from the variance of multiple AE parameters further show that under rapid loading,the variance rises sharply shortly be-fore peak stress,resulting in delayed and short-lived warning signals.With decreasing loading rate,the variance exhibits sustained growth with dense multi-peak features,triggering L1,L2,and L3 warning levels sequentially and significantly extending the warning window.Un-der fully quasi-static loading,variance fluctuations become more frequent,enabling earlier identification of accelerated crack coalescence.These results indicate that a lower loading rate promotes more complete fracture evolution and enhances the identifiability of failure pre-cursors.The findings provide deeper insight into rock fracture characteristics and offer a theoretical basis for stability monitoring and dis-aster early warning in deep rock engineering.

Abstract:The development of mineral resources has been a fundamental pillar supporting China's rapid modernization and economic growth.However,this extensive exploitation has concurrently and inevitably induced a series of significant ecological and environmental challenges,including land degradation,water resource depletion and pollution,air pollution,and biodiversity loss.In the current era,guided by the national strategic objectives of achieving"Carbon Peak and Carbon Neutrality"(the"Dual Carbon"goals)and embracing the holistic ecological philosophy of the"Life Community of Mountains,Rivers,Forests,Farmlands,Lakes,Grasslands,and Deserts,"ecolo-gical restoration in China's mining areas is undergoing a profound and essential transformation.This shift is moving away from traditional,often simplistic remediation methods towards a new paradigm that emphasizes green,low-carbon development and,most critically,integ-rated and systematic restoration.Despite this positive directional shift,the current practice of mining area ecological restoration in China is still largely plagued by a"fragmentation"dilemma.This predicament is prominently manifested in three key aspects:a persistent focus on single-element management,the adoption of a single-scale perspective,and an over-reliance on a single,often narrowly focused,technolo-gical solution.This fragmented approach struggles to effectively support the restoration of complex mining ecosystems and constrains the sustainability of restoration outcomes.In response,based on the holistic,systematic,and synergistic requirements of the Life Community concept,this study systematically elaborates on the connotation of"Integrated Ecological Restoration in Mining Areas".It explores the supporting theories for this integrated approach and proposes implementation pathways,models,and a key technology system for integ-rated mining area restoration from the perspectives of multi-element synergy,multi-scale linkage,and whole-process management.The main conclusions are as follows:① From the perspectives of elements,scales,and processes,the connotation of"Integrated Ecological Restoration in Mining Areas"is proposed,emphasizing the systemic,synergistic,and sustainable nature of ecological restoration in these areas.This moves beyond isolated interventions towards a comprehensive understanding of the ecosystem as an interconnected whole.②A supporting theoretical framework for integrated ecological restoration in mining areas is constructed,centering on the Life Community Theory,Landscape Ecology Theory,Scale Theory,and Life Cycle Theory.This multi-dimensional theoretical foundation provides the ne-cessary principles for guiding the holistic restoration of complex mining ecosystems,addressing interactions across biological,physical,and temporal dimensions.③ Centered around the ecosystem restoration pathway of"Pattern-Process-Service-Sustainability",a tripartite implementation path for integrated ecological restoration in mining areas is proposed.This path integrates"Multi-element Synergy,Multi-scale Linkage,and Whole-process Management"into a unified framework,ensuring coordinated action across different ecosystem com-ponents,hierarchical levels,and all stages from pre-mining planning to post-closure monitoring.④ A key technology system for integ-rated ecological restoration in mining areas,coupling multiple techniques,has been synthesized.This system includes:"Air-Space-Ground-Deep"integrated monitoring technologies for comprehensive data acquisition;the coupled application and synergy of physical,chemical,and biological restoration techniques to address diverse degradation issues;technologies for the systematic restoration of the soil-hydro-logy-vegetation complex,recognizing their tight interlinkages;and concurrent mining and rehabilitation techniques to minimize the restor-ation lag time and integrate restoration into active mining operations.This integrated technological suite provides practical tool support for the implementation of ecological restoration projects in mining areas.

Abstract:In the process of mining thick coal seams,the overlying rock layer will undergo a gradual dynamic evolution from local deform-ation to overall failure under the action of mining stress,and it is easy to form underground spaces such as in-situ goafs,low-level collapse zones,and high-level separation zones,which in turn cause geological problems such as rock stratum movement and surface subsidence.At the same time,the accumulation of coal-based solid waste such as coal gangue generated by coal mining not only occupies land,but also has the risk of environmental pollution,and its disposal demand is highly compatible with the key space formed by the migration of overburden rock from thick coal seam mining.Therefore,this paper systematically studies the dynamic evolution process of the overbur-den space of thick coal seam mining,and reveals the characteristics of three stages:initial mining,mining development,and mining stabil-ity.By analyzing the control mechanism of internal attributes and external factors on the evolution of overburdened rock,the formation mechanism and distribution law of key spaces are clarified,and the differentiated processes of in-situ goaf grouting,low-level collapse zone grouting and high-level separation grouting are proposed,and then a multi-level collaborative grouting and filling system of"lower bearing-middle solid-top control"is constructed.Similar simulation tests were carried out to study the dynamic evolution of key space and grouting filling effect of overburdened rock,and the collapse,fracture development and separation formation process in the dynamic evol-ution of overburden rock were reproduced,and the control effects of in-situ goaf grouting,low-level collapse zone grouting and high-level separation grouting on the movement of overburden rock were quantitatively analyzed,which provided an experimental basis for theoretic-al analysis conclusions and optimization of technical parameters.In terms of engineering applications,the grouting in the goaf of Baozigou Coal Mine,the grouting in the rising area of Renjiazhuang Coal Mine and the separation grouting of Huoerxinghe Coal Mine have all real-ized the large-scale disposal of coal-based solid waste,verified the adaptability of grouting and filling technology system under different geological conditions,and achieved the effect of improving the stability of overburden rock and effectively controlling surface subsidence,providing a generalizable practice example for green mining of thick coal seams.Through the closed-loop verification of theory,experi-ment and practice,the internal relationship between the evolution of overburden rock in thick coal seam mining and grouting and filling is clarified,and a multi-layer collaborative control technology system for thick coal seam mining is constructed,which provides some theor-etical support and technical paradigm for the prevention and control of overburden disasters and the resource utilization of coal-based sol-id waste in thick coal seam mining.

Abstract:"Detailed Rules for Water Prevention and Control in Coal Mines"and"Code for the Setting of Coal Pillars and Coal Mining in Buildings,Water Bodies,Railways and Main Mines"are not only the cornerstone of coal mine water prevention and control work,but also the highest technical standards.Their authority comes from their scientific and rigorous nature.In order to maintain the authority of the regulations(norms)and better guide the retention of water resistant coal(rock)pillars in coal mines,twelve opinions on the provisions of Appendix 6 of"Detailed Rules"and Appendix 4 of"Three Down Mining Norms"are proposed for discussion:firstly,the meaning of the example diagram is vague,such as what is the standard for drawing auxiliary lines in Appendix 6-3c of"Detailed Rules"Due to the vague meaning,L,and L2 have no solution,and the example diagram needs to be modified.Secondly,there is an error in the calculation formula,such as the incorrect formula in Appendix 6-5 of"Detailed Rules",The formulas in Annex 6-8 of Detailed Rules are meaningless after de-duction.The expression and attached diagram for the waterproof coal(rock)pillar with a filling water blocking zone at the top of the aquifer given in the"Three Bottom Mining Standards"are incorrect and need to be modified.The third issue is the omission of influen-cing factors,such as the"Detailed Rules"which did not take into account the movement angle of the overlying strata during mining when setting up water resistant coal(rock)columns for water drilling.Therefore,it is necessary to modify the example diagram and calculation formula.The fourth issue is that the reference standards are not unified.For example,formulas 6-6 and 6-8 in the"Detailed Rules"are both"borrowed"from the formula for sudden water coefficient,but the"borrowed"standards are not unified.It is recommended to unify the standards.Fifth,the parameters are not clear,such as the concept of"rock column"and the unit of water pressure in"λ is the ratio of water pressure to rock column width",which results in the formula having no solution or being unable to apply;The object(water source)to be protected against water blocking coal(rock)pillars in adjacent mines is unclear,and the applicable conditions need to be clarified;The re-tention of water resistant coal(rock)pillars in adjacent mines bounded by faults is detached from reality due to the unclear"boundary"of the mine,and has become a simple problem of retaining water resistant coal(rock)pillars on faults.Sixth,the title summary is inappropri-ate,such as Appendix 6-2 and Appendix 6-3 of the Detailed Rules,which fail to grasp the essential difference of the problem;The main title of Appendix 6-3 contradicts the second subheading under its control(the main title is for water conducting faults,and the second sub-heading under the main title only applies to non water conducting faults)and should be corrected;The main title of Appendix 6-4 conflicts with the second subheading under its control(the main title is water conducting fault,and the subheading is non water conducting fault),and the title needs to be modified.The seventh issue is the confusion of the starting standards for the two ends of the waterproof coal(rock)pillar.Some are based on the intersection point between the coal seam floor and the fault plane,while others are based on the intersection point between the coal seam roof and the fault plane.This is not just a normative issue,but also related to whether the calculation formula is correct and has a solution.For example,the formula in Annex 6-4 of the Detailed Rules does not consider the thickness of the coal seam and needs to be revised.The eighth issue is the vague definition of the concept,such as whether the height of the water conducting frac-ture zone refers to the vertical height or the normal height being unclear.The calculation formula and accompanying drawings for the height of the water conducting fracture zone indicate that it includes urban collapse zones,which contradicts the explanation of the term(the water conducting fracture zone does not include collapse zones).It is recommended to further clarify the concept of the height of the water conducting fracture zone based on the dip angle of the coal seam,and clarify the difference between the height of the water conduct-ing fracture zone and the height of the water conducting fracture zone.It is necessary to clarify whether the width of the waterproof coal(rock)pillar refers to the horizontal width or the inclined width.There are conceptual errors in the calculation of the water conducting frac-tured zone from the coal seam floor in Figure 6-8b of the Detailed Rules.The ninth is that the applicable conditions are vague,such as the retention of water-resistant coal(rock)pillars in the weathered zone of coal seam outcrops,and further clarification is needed on the applic-able conditions for retaining coal pillars.Example figure 6-3c is only applicable to non water conducting faults and should be pre correc-ted.Ten is an error in the example diagram,as shown in Figure 6-7 of the Detailed Rules,which classify the roof waterproof coal(rock)pillar as a goaf.The endpoint of Ls length referred to in Figure 6-8a of the Detailed Rules is unknown and needs to be modified.Eleven is the lack of example diagrams,such as the omission of the example diagram of"water bearing faults"in Appendix 6-2 of"Detailed Rules",which leads to unclear concepts of water bearing faults and requires the addition of example diagrams.Twelve is to focus on one aspect at the expense of another,as shown in Figure 6-8a of the"Detailed Rules",which only considers the principle that mining one mine must not damage the adjacent mine's waterproof coal(rock)pillars,but ignores the damage of mining one mine to the water conducting fault itself.It is necessary to modify the example diagram and add calculation formulas.

Abstract:Promoting the transition of coal resources from fuel to both fuel and raw material,and achieving clean and efficient utilization of coal are crucial approaches to addressing energy,resource,and environmental challenges in the 21st century.Coal quality assessment serves as the foundational work for clean and efficient coal utilization,while studies on occurrence patterns and controlling factors provide scientific support for coal quality evaluation.Taking the genesis of coal petrology and coal types as the starting point,the formation,evolu-tion,and controlling factors of special coal in Ningxia were analyzed.The distribution characteristics of special coal were found out,and the genetic types of special coal in Ningxia were classified.The results show that the sedimentary environments of the Taiyuan Formation,Shanxi Formation,and Yan'an Formation in Ningxia are mainly barrier coast,lake delta,and alluvial plain,respectively.The peat swamp types of the Taiyuan Formation and Shanxi Formation were dominated by humid forest swamps and humid herbaceous swamps,while those of the Yan'an Formation were mainly dry forest swamps.Influenced by both the sedimentary environments and the peat swamp types,the coal petrology and coal quality characteristics of the three sets of coal seams differ.During metamorphism,the coal was af-fected by deep metamorphism in Ningxia,and most of them have a low degree of metamorphism.The coal of the Taiyuan Formation in the Xiangshan coalfield and the coal in the western Weizhou mining area of the Ningdong coalfield underwent dynamic metamorphism super-imposed on deep metamorphism,and the coal in the Helanshan coalfield experienced regional magmatic thermal metamorphism superim-posed on deep metamorphism,and the coal have a higher degree of metamorphism.The spatiotemporal distribution characteristics of spe-cial coal in Ningxia were analyzed according to the requirements for coal petrology,coal quality and coal type of special coal.High-qual-ity anthracite is distributed in the Rujigou mining area.Coking coal is mainly located in the Hengcheng mining area,the eastern part of Weizhou mining area,the Siguquan mining area,the Shabatai mining area,the Shitanjing mining area and the Shizuishan mining area.Li-quefaction coal is mainly distributed in the Hongdunzi mining area,the Yuanyanghu mining area and the Lingwu mining area.Except for the above-mentioned areas,coal can be used as coal for gasification.The classification scheme for the genetic types of special coal in Ningxia was established based on sedimentary environments,peat swamp types,and metamorphic types.The special coal genetic types were divided into 16 categories,including 8 for the Taiyuan Formation,5 for the Shanxi Formation,and 4 for the Yan'an Formation(The Taiyuan Formation and Shanxi Formation both contain the genetic type of"lake delta humid forest swamp deep metamorphic process").The results provide theoretical support for the clean and efficient utilization of coal in Ningxia.

Abstract:L-shaped well extraction in fracture zones is an effective method to reduce gas disasters in coal mine working faces,but it faces significant technical challenges,such as difficulties in selecting layers and locations,and poor stability of horizontal sections.Take the East 1100 working face of the Weijiadicoal mine as the research area,Based on geological engineering applicability analysis and fine character-ization of overlying rock structures,the key stratum theory,O-ring theory,and high-level annular fracture zone model were used to de-termine the optimal layer and location for L-shaped wells.Abaqus software was employed to simulate stress changes in different perfor-ated screen pipes under mining conditions,and the optimal screen pipe specifications were selected.Engineering practices and extraction effect evaluations were further conducted.The results show that:① The east 1100 working face has high gas content and pressure,with the maximum horizontal principal stress direction in the NE.The coal mining adopts an upward-inclined advance and U-type ventilation,making it suitable for L-shaped well extraction in fracture zones.② The sandstone layer 70 m above the coal seam,located in the fracture zone(41-140 m),has a large Young's modulus(37.53 GPa),small Poisson's ratio(0.30),significant thickness(＞5 m),and good continuity,making it the optimal vertical layer for the horizontal section.The O-ring fracture zone at 70 m above the roof,28.43-59.73 m from the re-turn airway,is the optimal horizontal plane location.③ A staggered arrangement of circular perforations(10 mm diameter,250 mm spa-cing,20 holes/m)results in the smallest maximum principal stress and strain values,making it the optimal perforation layout for L-shaped well implementation.④ During the actual drilling process,CMD-100 drilling rig,7LZ172×7.0-XISF single-bend 1.5° screw drilling tool and MWD wireless three-opening drilling while drilling were used to complete the screen pipe.The pure volume of negative pressure gas extraction fluctuated at a high level between 0.4 × 104 m3/d and 1.1 × 104 m3/d,with stable production lasting over 500 days.During this period,the spacing of high-level boreholes in the working face was adjusted from 20 m per group to 50 m per group,the ventilation volume was reduced from 1850 m3/min to 1 470 m3/min,and the extraction rate increased from 52％to 75％,achieving integrated preven-tion and control of mine gas and fire hazards.

Abstract:In order to realize the intelligent and normal operation of the working face,and solve the problems of insufficient model gener-alization ability under complex geological conditions,the need to improve the collaborative efficiency of multiple equipment and the lack of full-link standardization solutions,an intelligent coal mine mining system based on digital twin and planning coal release collaboration is developed.Through hierarchical decoupling and modularization,the five-layer architecture of the digital twin system and the five func-tional modules of the planning coal discharge system are established,and internal and external system interactions are established through multi-source data fusion and cross-system protocol interconnection,and a complete interaction system covering data sharing,instruction is-suance,intelligent analysis and three-dimensional visual monitoring is built to form a standardized solution.A full-link digital twin system integrating 3D modeling,data fusion,industrial Internet of Things,RBF neural network dynamic game algorithm and other technical means has been established to realize geological exploration,equipment control,process optimization and other functions.An intelligent coal discharge decision-making model with dynamic parameter adaptation as the core is established,and a multi-objective collaborative optimization coal discharge decision-making framework is constructed by integrating coal seam geological parameters,equipment state parameters and process constraint rules,so as to realize the adaptive control of coal discharge process under complex geological condi-tions and the dynamic collaboration and optimization of data-driven coal discharge process.An intelligent coal discharge remote collabor-ative operation platform has been developed,which realizes the functions of visualizing the coal discharge process table,coal discharge data statistics and analysis,and distributing coal discharge templates,which improves the accuracy and safety of coal discharge operations and reduces the degree of manual intervention.In the Wudong Coal Mine in Xinjiang,the intelligent mining test of the coal mine was car-ried out,and the accuracy of the execution of the planned coal discharge system reached 93％,the automation rate of the production sys-tem reached 95％,the mining efficiency was increased by 11％,and the equipment failure rate was reduced by 7％,which greatly im-proved the accuracy and safety of intelligent mining.

Abstract:Hydraulic fracturing is the key technology for efficient development of coalbed methane.The distribution and communication of hydraulic fractures directly affect the fracturing effect.The research progress of true triaxial physical experiment,numerical simulation and field engineering test is systematically combed around the mechanism of hydraulic fracture propagation in coal seams.The effect of geolo-gical factors and construction factors on hydraulic fracture propagation is discussed,and the problems and development trends in the study of hydraulic fractures in coal are summarized.The conclusions show that the true triaxial physical simulation test system can simulate the in-situ stress and temperature conditions of the reservoir,and the formed multi-well type specimens can simulate open-hole and directional perforation fracturing,and the acoustic emission,electrical and optical monitoring systems are used to describe the fracture morphology.Secondly,the numerical simulation method for crack propagation has been extended from single finite element method,extended finite element method,boundary element method and discrete element method to continuum-discontinuum element method which combines fi-nite element method and discrete element method.It can simulate crack propagation along any path without remeshing.Thirdly,the field verification method can reflect the fracture propagation morphology under real geological-engineering coupling.While verifying the res-ults of physical experiment and numerical simulation,it reveals the new problems encountered in the application of fracturing technology.Finally,the propagation behavior of hydraulic fractures is affected by the coupling of geological-engineering factors such as in-situ stress,natural weak surface,rock mechanics parameters,displacement,fracturing fluid viscosity,fracturing fluid dosage,and perforation paramet-ers.In order to further explore the propagation law of fractures under ultra-large-scale volume fracturing,the development proposal such as improving the visual true triaxial hydraulic fracturing simulation test system,developing a multi-fusion hydraulic pressure numerical meth-od,and constructing an integrated platform for quantitative analysis of the sensitivity of fracture main controlling factors and intelligent de-cision-making of fracturing parameters are proposed.Through the comprehensive analysis of the existing literature,the research methods and influencing factors of fracture propagation are summarized in order to provide reference for subsequent research and practice.

Abstract:As the dominant energy source in China,coal mining,storage,and transportation continually face prominent occupational health risks and coal dust explosion hazards,which severely constrain the industry's safety and sustainable development.To achieve the goal of intrinsic safety in coal mine production,this paper systematically reviews the technical principles and mechanisms of current dust control and explosion prevention technologies.It proposes an integrated concept of dust suppression and explosion prevention centered on"source control and intrinsic safety,"and outlines future development directions.At the theoretical research level,a systematic understanding has been formed regarding dust migration patterns,wetting and agglomeration mechanisms,and explosion characteristics:dust diffusion is in-fluenced by the multi-field coupling of airflow,dust sources,and spatial configuration;wettability is regulated by functional group types and particle size,while agglomeration is governed by the synergistic effects of inertial,diffusional,and electrostatic mechanisms;explo-sion sensitivity and intensity parameters are closely related to the oil content,particle size,and environmental conditions of coal dust.At the technological research level,dust prevention and control have established a full-process system encompassing"source dust reduction,process dust control,individual protection,"while explosion prevention has constructed a three-tier protection chain of"explosion preven-tion,explosion suppression,explosion isolation".Based on the above theoretical and technical foundations,an integrated dust suppression and explosion prevention framework centered on whole-process coordination is proposed,aiming to achieve full coverage from dust source control to explosion propagation blocking.This framework focuses on two main research directions:the development of integrated system equipment and multi-functional composite materials,to overcome key challenges such as weak sensing-decision foundations,a lack of dy-namic evolution models for the dust accumulation-to-explosion chain,unclear structure-property relationships in composite materials,and insufficient environmental adaptability.Future research should focus on deepening the understanding of multi-phase medium and explo-sion coupling mechanisms,innovating environmentally adaptive materials and smart sensing devices,and establishing an integrated"per-ception-decision-material-execution"intelligent collaborative system.By breaking through these scientific and technical bottlenecks,it is expected to systematically advance the reliability and intelligence of integrated dust suppression and explosion prevention technologies.This will provide a solid foundation for the green,safe,and efficient high-quality development of the coal industry and contribute to the comprehensive construction of intrinsically safe mines.

Abstract:To address the challenges of safe and efficient mining in steeply dipping coal seams in China and support the intelligent trans-formation of the coal industry,this article focuses on fully mechanized longwall mining technology for such seams.It systematically re-views the theoretical and technological evolution of longwall mining in steeply dipping coal seams and,in light of intelligent mining trends,outlines future scientific issues and technological development directions in this field.Since its formal definition in 1996,steeply dipping coal seams,with dip angles ranging from 35° to 55°,have seen their upper mining limit gradually extend to 70° due to advances in technology and equipment.These seams are widely distributed across China with substantial reserves,serving as vital resources for region-al socioeconomic development while also posing key challenges for intelligent mining.The article systematically outlines the four devel-opmental stages of longwall mining in steeply dipping coal seams:non mechanization dominance,mechanization exploration,break-through in fully mechanized mining,and technological system maturation.From the perspectives of thin,medium thick,and thick or ultra-thick seams,it summarizes the applicability,advantages,and limitations of various mining methods such as wire saw mining,pseudo in-clined directional longwall mining with segmental dense support,fully mechanized mining,and fully mechanized caving.It notes that fully mechanized longwall mining,including caving,remains the mainstream technological direction.In terms of theoretical research,key ad-vances are introduced,including the relationship between support and surrounding rock in steeply dipping longwall faces,roof structure stability,floor sliding mechanisms,support surrounding rock system dynamics,coal wall stability,flying gangue mechanisms,overburden structure and disaster inducing mechanisms.Technological innovations such as longwall pseudo inclined mining,nonlinear face layout,and combined horizontal section fully mechanized caving mining along with related intelligent equipment development are also reviewed.In response to the current trend toward intelligent mining,the establishment of digital twin simulation platforms based on longwall mining,the development of intelligent integrated equipment,and practical cases of intelligent mine applications are discussed.It is emphasized that intelligent fully mechanized longwall mining is the essential pathway toward safe and efficient extraction of steeply dipping coal seams.Finally,the article identifies pressing research issues such as intelligent surrounding rock control,collaborative stability of equipment sys-tems,and reliability of complex environmental perception.Future technological development directions are proposed,offering theoretical and technical support for promoting safe,efficient,and intelligent mining in steeply dipping coal seams.

Abstract:The year 2026 marks the beginning of China's"15th Five-Year Plan"period.Building on past achievements and advancing coal mine water disaster prevention and control work is a critical task for achieving high-quality development in the coal industry.Based on the statistical analysis of typical water disasters in coal mines of China during the"14th Five-Year Plan"period,our research focuses on re-viewing the major technological advancements made in water inflow prediction,water disaster exploration,and control.It also provides in-depth reflection and outlook on the future technological development directions.This work highlights the following key advancements dur-ing the"14th Five-Year Plan"period:① Development of dynamic prediction methods for water inflow in mining faces;② Valuable ex-periences and practices have been gained in the precise prevention and control of high-position separated layer water hazards;③ The tech-nologies and methods for active water reduction at the source are showing a diverse development trend;④ The geophysical exploration technology within and between boreholes,as well as the seismic detection technology for mining/excavation,are showing a burgeoning de-velopment momentum;⑤ Increasing integration of transparent geology into water disaster prevention,revolutionizing concepts and evalu-ation methods;⑥ The concept of water disaster prevention and control management has been continuously improved,and the require-ments for water disaster prevention and control work in coal mines from technical management and government regulatory have become more specific and comprehensive.Based on the summarizing six new advancements in water disaster prevention technologies,this study identifies the main current challenges and issues in coal mine water disaster prevention.Starting from the technical needs for water dis-aster prevention during the 15th Five-Year Plan period,it proposes considerations and suggestions in four technical directions:mine water source protection,intelligent prevention and control of water disasters,collaborative prevention and control of composite disasters,and the establishment of a technical standard system for water disaster management.

Abstract:Traditional mining engineering has long been trapped in the dilemma of"coexistence of mining operations and inherent risks".The duality of its high-risk nature and resource contribution has become increasingly prominent under deep mining conditions.As coal mining depth increases,the superposition of deteriorating static geological conditions and dynamic engineering disturbances frequently triggers problems such as roadway surrounding rock instability and stope failure.Conventional rock mechanics theories,relying heavily on simplified assumptions,are increasingly inadequate in complex engineering scenarios.In recent years,remarkable advancements have been made in coal mine digitalization and intellectualization;the popularization of sensor technology has significantly enhanced engineer-ing condition perception capabilities.However,issues including fragmented data governance,lagging theoretical cognition,and disconnec-tion between theory and engineering practice have led digital technologies to a"flashy but impractical"difficult position.To address these challenges,a digital rock mechanics solution is proposed by integrating data regularity,mechanical logic,and engineering experience.It establishes a technical pathway of"comprehensive perception-digital-driven-proactive hazard mitigation-pressure-relief mining",aiming to construct a new paradigm of scientific mining centred on digital engineering.Specifically:Static geological information is activated through digital exploration and 3D modeling(geological assurance first,laying the foundation for transparent mining);The dynamic engin-eering environment is optimized via intelligent perception and machine learning(hazard prevention at the design source,forging a mining-friendly engineering setting);The transformation from"passive response"to"active prevention and control"is realized(digital engineer-ing technologies enabling precise pressure relief and autonomous linkage of coordinated control).This pathway not only resolves key tech-nical bottlenecks,such as roadway deformation and stope instability in deep mining,promoting innovation and transformation from engin-eering disaster causation to engineering disaster prevention,but also facilitates the safe and efficient mining of kilometre-deep wells,thereby safeguarding national energy security.The engineering paradigm of digital rock mechanics is expected to revolutionize under-ground rock engineering,offering sustainable,safe,and intelligent solutions for the coal industry and related fields.

Abstract:As a foundational technological bedrock spanning the entire coal industry chain,from mining and processing to utilization-common coal technologies represent fundamental,versatile core technologies that underpin the industrial upgrading and high-quality de-velopment of the coal sector.They play a significant role in advancing the transformation of the coal industry toward premium,intelligent,and green development.This paper analyzes the global energy transition trends,structural shifts,and China's energy production and con-sumption patterns,proposing a technological pathway for the transformation and sustainable high-quality development of the coal industry through the transplantation of advanced technologies and innovation in common technologies.It comprehensively elaborates on the major progress achieved in intelligent,green,and efficient coal mining,as well as clean,efficient,and low-carbon coal utilization technologies.Furthermore,it introduces an innovative technological pathway for the coupled development of coal-power-chemicals-new energy sys-tems,facilitating a green transformation and upgrading of the coal industry through bidirectional empowerment:"new energy decarbon-izes coal development,while coal provides a safety net for new energy."Focusing on six key dimensions of common technologies in the industry-basic scientific challenges in coal development,common technologies for coal safety production,intelligent unmanned/minimally manned mining technologies,common green mining technologies,clean and efficient coal utilization,and the integration of AI+re-sources+energy+ecological smart complexes,this study systematically outlines the major challenges facing the high-quality develop-ment of the coal industry.It identifies breakthrough directions,key research priorities,and systematic solutions for common technologies.Based on the current state of common technology development in coal mining,processing,and utilization in China,the paper offers predic-tions for the"15th Five-Year Plan"period:achieving holographic interaction and intelligent decision-making between geological models and mine production systems;breaking through the construction of multimodal vertical large models in coal mines;advancing the R&D and engineering demonstration of 10 kV technical equipment for working faces;upgrading and iterating technologies such as inertial nav-igation and precise personnel positioning;demonstrating routine unmanned/minimally manned mining in thin and relatively thin coal seams;conducting engineering demonstrations of 20 Mt annual output in 500 m ultra-long faces in thick seams;demonstrating intelligent unmanned/minimally manned mining under complex conditions in deep mines with rock burst risks;overcoming technical barriers in con-tinuous mining systems and intelligent semi-continuous unmanned/minimally manned technologies with complete equipment packages for open-pit coal mines;and promoting the widespread adoption of green mining technologies alongside comprehensive upgrades in intelli-gent coal preparation equipment.Long-term predictions for 2030 to 2050 are also proposed:by mid-century,a well-established system of intelligent green mining technologies and equipment will be gradually formed,achieving new breakthroughs in high-end coal conversion and utilization technologies.This will drive the efficient operation of a flexible,intelligent,and green coal supply system,fostering a new industrial landscape characterized by the full integration of coal-power-chemicals-new energy sectors,thereby ushering the coal industry into a new phase of high-quality development.The paper further proposes an innovation architecture for common coal technologies.By es-tablishing a closed-loop innovation ecosystem of"policy guidance,resource supply,application feedback,service support,"it aims to pro-pel the coal industry toward premium,intelligent,and green transformation,thereby providing a sustained supply and guarantee of com-mon technologies for the sustainable,high-quality development of the coal sector.