Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for ...Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for mineral resources and energy,the challenges associated with groundwater control and rock mass stability have grown increasingly critical.These challenges are exacerbated by complex geological conditions,structural heterogeneity,and intense mining-induced disturbances.This special issue seeks to address these challenges by showcasing cutting-edge research and technological advancements in the field.展开更多
Mining-related seismicity poses significant challenges in underground coal mining due to its complex rupture mechanisms and associated hazards.To bridge gaps in understanding these intricate processes,this study emplo...Mining-related seismicity poses significant challenges in underground coal mining due to its complex rupture mechanisms and associated hazards.To bridge gaps in understanding these intricate processes,this study employed a multi-local seismic monitoring network,integrating both in-mine and local instruments at overlapping length scales.We specifically focused on a damaging local magnitude(ML)2.6 event and its aftershocks that occurred on 10 September 2022 in the vicinity of the 3308 working face of the Yangcheng coal mine in Shandong Province,China.Moment tensor(MT)inversion revealed a complex cascading rupture mechanism:an initial moment magnitude(M_(w))2.2 normal fault slip along the DF60 fault in an ESEeWNW direction,transitioning to a M_(w)3.0 event as the FD24 and DF60 faults unclamped.The scale-independent self-similarity and stress heterogeneity of mining-related seismicity were investigated through source parameter calculations,providing valuable insights into the driving mechanism of these seismic sequences.The in-mine network,constrained by its low dynamic changes,captured only the nucleation phase of the DF60 fault.Furthermore,standard decomposition of the MT solution from the seismic network proved inadequate for accurately identifying the complex nature of the rupture.To enhance safety and risk management in mining environments,we examined the implications of source reactivation within the cluster area post-stress-adjustment.This comprehensive multiscale analysis offers crucial insights into the complex rupture mechanisms and hazards associated with mining-related seismicity.The results underscore the importance of continuous multi-local network monitoring and advanced analytical techniques for improved disaster assessment and risk mitigation in mining operations.展开更多
Salt deposits in China predominantly originate from lake deposits,characterized by thin salt beds interspersed with numerous interlayers,collectively termed bedded salt formations.Historically,the solution mining prac...Salt deposits in China predominantly originate from lake deposits,characterized by thin salt beds interspersed with numerous interlayers,collectively termed bedded salt formations.Historically,the solution mining practices have adopted the layered solution mining approach,inspired by coal mining techniques.However,this approach fails to account for the unique challenges of salt solution mining.Practical implementation is inefficient,costs escalate post-construction,and cavern geometry is constrained by salt beds thickness.Additionally,resource loss in abandoned beds and stability risks in adjacent mining zones remain unresolved.This study investigates mining scheme selection for low-grade salt deposits in Huai'an Salt Basin,introducing a continuous solution mining method that traverses multiple interlayers.Through comprehensive analysis of plastic deformation in caverns and surrounding rock,volume shrinkage rates,and economic costs comparing continuous and layered solution mining approaches,the results demonstrate that:(1)In the layered solution mining with horizontal interconnected wells scheme,plastic deformation zones propagate unevenly,posing interlayer connectivity risks.Concurrently,roof subsidence and floor heave destabilize the structure;(2)the continuous solution mining with horizontal interconnected wells scheme reduces plastic deformation zones to 3.4%of cavern volume,with volumetric shrinkage below 17%,markedly improving stability;(3)Economically,the continuous solution mining scheme generates caverns 2.43 times larger than the layered solution mining,slashing unit volume costs to 41.1%while enhancing resource recovery and long-term viability.The continuous method demonstrates distinct economic advantages and achieves higher resource utilization efficiency in solution mining compared to layered mining.Furthermore,its superior cavern stability presents strong potential for large-scale implementation.展开更多
With the third innovation in science and technology worldwide, China has also experienced thismarvelous progress. Concerning the longwall mining in China, the ＂masonry beam theory＂ （MBT） wasfirst proposed in the 1...With the third innovation in science and technology worldwide, China has also experienced thismarvelous progress. Concerning the longwall mining in China, the ＂masonry beam theory＂ （MBT） wasfirst proposed in the 1960s, illustrating that the transmission and equilibrium method of overburdenpressure using reserved coal pillar in mined-out areas can be realized. This forms the so-called ＂121mining method＂, which lays a solid foundation for development of mining science and technology inChina. The ＂transfer rock beam theory＂ （TRBT） proposed in the 1980s gives a further understanding forthe transmission path of stope overburden pressure and pressure distribution in high-stress areas. In thisregard, the advanced 121 mining method was proposed with smaller coal pillar for excavation design,making significant contributions to improvement of the coal recovery rate in that era. In the 21st century,the traditional mining technologies faced great challenges and, under the theoretical developmentspioneered by Profs. Minggao Qian and Zhenqi Song, the ＂cutting cantilever beam theory＂ （CCBT） wasproposed in 2008. After that the 110 mining method is formulated subsequently, namely one stope face,after the first mining cycle, needs one advanced gateway excavation, while the other one is automaticallyformed during the last mining cycle without coal pillars left in the mining area. This method can beimplemented using the CCBT by incorporating the key technologies, including the directional presplittingroof cutting, constant resistance and large deformation （CRLD） bolt/anchor supporting systemwith negative Poisson＇s ratio （NPR） effect material, and remote real-time monitoring technology. TheCCBT and 110 mining method will provide the theoretical and technical basis for the development ofmining industry in China.展开更多
In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining （NM）, top-coal caving mining （TCM） and protective coal-seam mining （...In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining （NM）, top-coal caving mining （TCM） and protective coal-seam mining （PCM）, are modeled using discrete element software UDEC, The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields, For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest, The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively, The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM, It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential, The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high- efficiency coal mining,展开更多
1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrest...1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrestrial ecosystems.展开更多
As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during min...As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.展开更多
In the gas-coal integrated mining field,the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline's safety requirements.Considerin...In the gas-coal integrated mining field,the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline's safety requirements.Considering the coal pillar recovery rate and pipeline's safety requirements,two new shaped coal pillar design approaches for subsurface pipelines were developed.Firstly,the deformation limitations for measuring pipeline safety are categorized into two:no deformation is permitted,and deformation is acceptable within elastic limits.Subsequently,integrating the key stratum theory(KST)and cave angle,a fishbone-shaped coal pillar design approach that does not permit pipeline deformation is established.Meanwhile,combined with the ground subsidence and the pipeline's elastic deformation limit,a grille-shaped coal pillar design approach that accepts deformation pipelines within elastic limits is established.Those two new approaches clarify parameters including mined width,coal pillar width and mined length.Finally,the case study shows that the designed mined width,coal pillar width and mined length of the fishbone-shaped coal pillar are 90,80,and 130 m,while those of the grille-shaped are 320,370,and640 m.Compared with the conventional method,the fishbone-shaped and grille-shaped coal pillar design approaches recovered coal pillar resources of 2.65×10~6and 5.81×10~6t on the premise of meeting the pipeline safety requirements,and the recovery rates increased by 20.5%and 45.0%,with expenditures representing only 56.46%and 20.02%of the respective benefits.These new approaches provide managers with diverse options for protecting pipeline safety while promoting coal pillar recovery,which is conducive to the harmonic mining of gas-coal resources.展开更多
Underground coal mining induces significant surface deformation and environmental damage,particularly in deeply buried mining areas with thin bedrock and thick alluvial layers.Based on the case study of the Zhaogu No....Underground coal mining induces significant surface deformation and environmental damage,particularly in deeply buried mining areas with thin bedrock and thick alluvial layers.Based on the case study of the Zhaogu No.2 coal mine in Xinxiang City,Henan Province,China,this study employs a comprehensive research methodology,integrating field investigations,numerical simulations,and theoretical analyses,to explore the surface subsidence features at deeply buried mining areas with thin bedrock and thick alluvial layers,to reveal the effect of alluvial thickness on the surface subsidence characteristics.The findings indicate that the surface subsidence areas span 4.2 km2 with an advanced influence distance of 540 m.The rate of surface subsidence primarily depends on the panel's position and its advancing rate.Moreover,the thickness of the alluvial layer amplifies both the extent and magnitude of surface deformation.The displacement of overlying rock primarily exhibits a two-stage progression:the thin bedrock control stage and the alluvial control stage.In the thin bedrock control stage,surface subsidence initiates with relatively low subsidence values and amplitudes.Subsequently,in the alluvial control stage,surface subsidence accelerates,leading to a rapid increase in both subsidence values and amplitudes.These characteristics of rock formation displacement result in distinct phases of surface subsidence.Furthermore,the paper addresses the utilization of surface subsidence areas and proposes a method for calculating reservoir storage capacity in these areas.According to calculations,the storage capacity amounts to 1.05e7 m^(3).The research findings provide valuable insights into the surface subsidence laws in regions with similar geological conditions and practical implications for the management and utilization of subsided areas.展开更多
The complex and diverse nature of coal mining sites,including different landforms and working conditions,presents challenges for rehabilitation efforts.To address this,we conducted a comprehensive experimental study f...The complex and diverse nature of coal mining sites,including different landforms and working conditions,presents challenges for rehabilitation efforts.To address this,we conducted a comprehensive experimental study focusing on microbially induced calcium carbonate precipitation(MICP)remediation,considering the fracture characteristics of coal mining sites.The MICP-restored samples were subjected to confined/unconfined compressive strength,uniaxial/triaxial permeability,and souring tests to assess their restoration efficacy.The results showed that under similar mining conditions,the average depth of parallel fractures was 0.185 m for loess ridges,0.16 m for the valley,and 0.146 m for the blown-sand region,while the average depth for boundary fractures was 0.411 m for loess ridges,0.178 m for the valley,and 0.268 m for the blown-sand region.Notably,parallel fractures showed negligible filling in all landforms,whereas boundary fractures in the blown-sand region were completely filled with wind-deposited sand.The valley landform was filled with alluvium and wind-deposited sand,whereas the loess landform was filled with wind-deposited sand and loess.MICP-restored soil samples in all landforms achieved a strength comparable to remolded fracture-free soil samples.Across all landforms,the maximum permeability coefficient of MICP-restored soil samples closely matched that of remolded fracture-free soil samples.Under similar topographic and rainfall conditions MICP restorations scoured 31.3 g on blown-sand region,19.3 g on loess ridges,and 17.6 g on valleys.These research findings provide an experimental foundation for MICP repair of coal mining ground fractures.展开更多
Aiming at the problem that the distance between the main roadway and the working face in Hudi Coal Industry Panel was more than 100 m,which was still affected by mining,high stress concentration of the roadway,and dif...Aiming at the problem that the distance between the main roadway and the working face in Hudi Coal Industry Panel was more than 100 m,which was still affected by mining,high stress concentration of the roadway,and difficulty of supporting overall convergence of the section,the mechanical characteristics of the core bearing strata of the overlying rock caving in the working face were studied.The correlation mechanism between the overlying rock caving and the deformation and failure of the roadway was analyzed,and the quantitative evaluation index was established to comprehensively analyze different influencing factors.Based on the key strata theory,the mechanical difference transfer model of working face mining and panel roadway deformation and failure was established.It was considered that the difference in fracture morphology was the key to the far-field stress disturbance.The regional stress control technology was proposed to block or reduce the stress transfer,so that the peak stress of the panel main roadway was reduced,and the deformation of the surrounding rock was significantly reduced,which provides a reference value for the roadway support with serious influence of mining roadway.展开更多
Rapid and accurate recognition of coal and rock is an important prerequisite for safe and efficient coal mining.In this paper,a novel coal-rock recognition method is proposed based on fusing laser point cloud and imag...Rapid and accurate recognition of coal and rock is an important prerequisite for safe and efficient coal mining.In this paper,a novel coal-rock recognition method is proposed based on fusing laser point cloud and images,named Multi-Modal Frustum PointNet(MMFP).Firstly,MobileNetV3 is used as the backbone network of Mask R-CNN to reduce the network parameters and compress the model volume.The dilated convolutional block attention mechanism(Dilated CBAM)and inception structure are combined with MobileNetV3 to further enhance the detection accuracy.Subsequently,the 2D target candidate box is calculated through the improved Mask R-CNN,and the frustum point cloud in the 2D target candidate box is extracted to reduce the calculation scale and spatial search range.Then,the self-attention PointNet is constructed to segment the fused point cloud within the frustum range,and the bounding box regression network is used to predict the bounding box parameters.Finally,an experimental platform of shearer coal wall cutting is established,and multiple comparative experiments are conducted.Experimental results indicate that the proposed coal-rock recognition method is superior to other advanced models.展开更多
High-intensive underground mining has caused severe ground fissures,resulting in environmental degradation.Consequently,prompt detection is crucial to mitigate their environmental impact.However,the accurate segmentat...High-intensive underground mining has caused severe ground fissures,resulting in environmental degradation.Consequently,prompt detection is crucial to mitigate their environmental impact.However,the accurate segmentation of fissuresin complex and variable scenes of visible imagery is a challenging issue.Our method,DeepFissureNets-Infrared-Visible(DFN-IV),highlights the potential of incorporating visible images with infrared information for improved ground fissuresegmentation.DFNIV adopts a two-step process.First,a fusion network is trained with the dual adversarial learning strategy fuses infrared and visible imaging,providing an integrated representation of fissuretargets that combines the structural information with the textual details.Second,the fused images are processed by a fine-tunedsegmentation network,which lever-ages knowledge injection to learn the distinctive characteristics of fissuretargets effectively.Furthermore,an infrared-visible ground fissuredataset(IVGF)is built from an aerial investigation of the Daliuta Coal Mine.Extensive experiments reveal that our approach provides superior accuracy over single-modality image strategies employed in fivesegmentation models.Notably,DeeplabV3+tested with DFN-IV improves by 9.7%and 11.13%in pixel accuracy and Intersection over Union(IoU),respectively,compared to solely visible images.Moreover,our method surpasses six state-of-the-art image fusion methods,achieving a 5.28%improvement in pixel accuracy and a 1.57%increase in IoU,respectively,compared to the second-best effective method.In addition,ablation studies further validate the significanceof the dual adversarial learning module and the integrated knowledge injection strategy.By leveraging DFN-IV,we aim to quantify the impacts of mining-induced ground fissures,facilitating the implementation of intelligent safety measures.展开更多
It is of great significance to study the failure mode of mining roadways for safe coal mining.The unconventional asymmetric failure(UAF)phenomenon was discovered in the 9106 ventilation roadway of Wangzhuang coal mine...It is of great significance to study the failure mode of mining roadways for safe coal mining.The unconventional asymmetric failure(UAF)phenomenon was discovered in the 9106 ventilation roadway of Wangzhuang coal mine in Shanxi Province.The main manifestation is that the deformation of the roadway on the coal side is much greater than that on the coal pillar side.A comprehensive study was conducted on on-site detection,theoretical analysis,laboratory tests and numerical simulation of the UAF phenomenon.On-site detection shows that the deformation of the coal sidewall can reach 50–80 cm,and the failure zone depth can reach 3 m.The deformation and fracture depth on the coal pillar side are much smaller than those on the coal side.A calculation model for the principal stress of surrounding rock when the axial direction of the roadway is inconsistent with the in-situ stress field was established.The distribution of the failure zone on both sides of the roadway has been defined by the combined mining induced stress.The true triaxial test studied the mechanical mechanism of rock mass fracture and crack propagation on both sides of the roadway.The research results indicate that the axial direction,stress field distribution,and mining induced stress field distribution of the roadway jointly affect the asymmetric failure mode of the roadway.The angle between the axis direction of the roadway and the maximum horizontal stress field leads to uneven distribution of the principal stress field on both sides.The differential distribution of mining induced stress exacerbates the asymmetric distribution of principal stress in the surrounding rock.The uneven stress distribution on both sides of the roadway is the main cause of UAF formation.The research results can provide mechanical explanations and theoretical support for the control of surrounding rock in roadways with similar failure characteristics.展开更多
Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three f...Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three focused works to address this problem.Firstly,field measurements were conducted to clarify rib spalling characteristics:the coal wall is dominated by shear failure,internal cracks are mainly distributed 3–6 m above the coal wall surface,and the maximum depth of crack development reaches 3 m.Secondly,Universal Distinct Element Code(UDEC)numerical simulation software was used to build a rib spalling model,with the Trigon model adopted to divide the coal wall into blocks.Analysis of four key factors shows that increased buried depth and mining height significantly raise the total length of coal wall internal cracks,increasing rib spalling risk,while higher coal body strength and support strength effectively alleviate this phenomenon.Finally,an orthogonal experiment was designed to quantitatively determine the influence degree of the four factors on rib spalling.Results show that coal body strength has the greatest impact,followed by support strength,mining height,and mining depth in order of influence.This study provides valuable theoretical guidance for on-site prevention and control of coal wall rib spalling.展开更多
The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affect...The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affects strata movement characteristics,a physical model experiment was conducted based on the geological conditions of the Panel 122104 in Caojiatan Coal Mine in Shaanxi.The experiment examined strata movement at mining heights of 1 m and 10 m,identifying differences in detachment,collapse behavior,and collapse angles under these two conditions.The results indicate the following:Delamination range directly governs collapse patterns,with higher stress concentration accelerating delamination initiation and expanding affected zones.1 m mining height exhibits a“superposed fixed beam”structure with lower strength compared to the“fixed beam+cantilever beam”configuration under 10 m height.A model estimating collapse step shows 9.13%average error.Strata structure dictates collapse angle mechanisms:Pseudo-plastic deformation under 1 m height determines collapse angle through vertical tensile stress boundaries,whereas 10 m height exhibits brittle fracture behavior with collapse angles approximating fracture angles.Periodic collapse volume above working face directly correlates with mine pressure intensity and is positively correlated with the caving step distance,collapse angle,and caving range.These parameters show higher values under 10 m mining height,resulting in more pronounced mine pressure manifestations compared to 1 m conditions.展开更多
To ameliorate the difficulties of on-site dynamic disaster control in the end-mining stage of traditional mining engineering,this paper introduces the mathematical research and engineering application of the end-minin...To ameliorate the difficulties of on-site dynamic disaster control in the end-mining stage of traditional mining engineering,this paper introduces the mathematical research and engineering application of the end-mining technology system with non-pillar in mines(ETSNM)in recent years.The petal warning criterion for the stability of the surrounding rock of the roadway at the end-mining stage was obtained by studying the inverse problem of the petal theorem.A conformal mathematical model of the end-mining stage was established using the conformal mapping method,and the limit theorem of the peak point of mine pressure(LTPPMP)in the end-mining stage was demonstrated.Based on the cross-fusion of the above basic mathematical theory and the LTPPMP,a new ETSNM model was proposed,which includes no coal pillar,no dedicated retracement roadways,and fast retracement equipment(NNF).The mathematical principles of engineering technology for height control,speed limit,and roof cutting in the end-mining stage with non-pillar were revealed.The scientific and application values of the ETSNM were confirmed through engineering applications.Based on this,a new non-pillar control technology for dynamic disasters in the end-mining stage was proposed.The above research will play an active role in promoting the engineering application of ETSNM driven by mathematical theory.展开更多
Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer ...Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.展开更多
Understanding dynamic visualization of mining-induced stress is of great significance to disaster prevention and control in coal mining activities.In this study,three theoretical models,including linear,polynomial,and...Understanding dynamic visualization of mining-induced stress is of great significance to disaster prevention and control in coal mining activities.In this study,three theoretical models,including linear,polynomial,and exponential models,are proposed to inverse the mining-induced stress through the acquisition and analysis of hydraulic support stress and micro-seismicity in the coal mining face.The distribution of mining-induced stress in the coal seam are graphed by fitting two key stress parameters including hydraulic support stress and peak stress,and two key zones including goaf zone and in situ stress zone.These key stress parameters and zones are defined based on the critical nodes of the model curve.According to the geological background of Mataihao coal mine in Erdos,Inner Mongolia Autonomous Region,China,the contours of mining-induced stress are graphed through the stress calculation of these three inversion theoretical models.The multi-monitoring data of micro-seismicity,drilling chips,advanced borehole stress and bolts axial force are used to verify the key stress parameters and zones of the theoretical models.It shows that the monitoring data are in good agreement with the distribution of inversed results.It should be emphasized that,if the fault structure exists around the mining face,the mining-induced stress decreases obviously when the mining face is passing through the faults,and the location of the peak stress will be closer to the mining face.The results in this study could provide methods for early prevention of extreme mining-induced stress and disaster control in the mining activities.展开更多
The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and ...The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.展开更多
文摘Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for mineral resources and energy,the challenges associated with groundwater control and rock mass stability have grown increasingly critical.These challenges are exacerbated by complex geological conditions,structural heterogeneity,and intense mining-induced disturbances.This special issue seeks to address these challenges by showcasing cutting-edge research and technological advancements in the field.
基金funded by the National Natural Science Foundation of China(Grant No.51574225)Shandong Energy Group(Grant No.SNKJ2022BJ03-R28)for Caiping Lu+1 种基金the Research Team on MonitoringActivity Mechanisms of Unnatural Earthquakes of Shandong Earthquake Agency(Grant No.TD202301)for Chengyu Liu.
文摘Mining-related seismicity poses significant challenges in underground coal mining due to its complex rupture mechanisms and associated hazards.To bridge gaps in understanding these intricate processes,this study employed a multi-local seismic monitoring network,integrating both in-mine and local instruments at overlapping length scales.We specifically focused on a damaging local magnitude(ML)2.6 event and its aftershocks that occurred on 10 September 2022 in the vicinity of the 3308 working face of the Yangcheng coal mine in Shandong Province,China.Moment tensor(MT)inversion revealed a complex cascading rupture mechanism:an initial moment magnitude(M_(w))2.2 normal fault slip along the DF60 fault in an ESEeWNW direction,transitioning to a M_(w)3.0 event as the FD24 and DF60 faults unclamped.The scale-independent self-similarity and stress heterogeneity of mining-related seismicity were investigated through source parameter calculations,providing valuable insights into the driving mechanism of these seismic sequences.The in-mine network,constrained by its low dynamic changes,captured only the nucleation phase of the DF60 fault.Furthermore,standard decomposition of the MT solution from the seismic network proved inadequate for accurately identifying the complex nature of the rupture.To enhance safety and risk management in mining environments,we examined the implications of source reactivation within the cluster area post-stress-adjustment.This comprehensive multiscale analysis offers crucial insights into the complex rupture mechanisms and hazards associated with mining-related seismicity.The results underscore the importance of continuous multi-local network monitoring and advanced analytical techniques for improved disaster assessment and risk mitigation in mining operations.
基金supported by the National Natural Science Foundation of China(Nos.42177124 and 41877277)Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.SKLGME022011)+2 种基金Fundamental Research Funds for the Central Universities(No.2024KYJD1011)Frontier Technologies R&D Program of Jiangsu(No.BF2024056)the Graduate Innovation Program of China University of Mining and Technology(No.KYCX25_3085)。
文摘Salt deposits in China predominantly originate from lake deposits,characterized by thin salt beds interspersed with numerous interlayers,collectively termed bedded salt formations.Historically,the solution mining practices have adopted the layered solution mining approach,inspired by coal mining techniques.However,this approach fails to account for the unique challenges of salt solution mining.Practical implementation is inefficient,costs escalate post-construction,and cavern geometry is constrained by salt beds thickness.Additionally,resource loss in abandoned beds and stability risks in adjacent mining zones remain unresolved.This study investigates mining scheme selection for low-grade salt deposits in Huai'an Salt Basin,introducing a continuous solution mining method that traverses multiple interlayers.Through comprehensive analysis of plastic deformation in caverns and surrounding rock,volume shrinkage rates,and economic costs comparing continuous and layered solution mining approaches,the results demonstrate that:(1)In the layered solution mining with horizontal interconnected wells scheme,plastic deformation zones propagate unevenly,posing interlayer connectivity risks.Concurrently,roof subsidence and floor heave destabilize the structure;(2)the continuous solution mining with horizontal interconnected wells scheme reduces plastic deformation zones to 3.4%of cavern volume,with volumetric shrinkage below 17%,markedly improving stability;(3)Economically,the continuous solution mining scheme generates caverns 2.43 times larger than the layered solution mining,slashing unit volume costs to 41.1%while enhancing resource recovery and long-term viability.The continuous method demonstrates distinct economic advantages and achieves higher resource utilization efficiency in solution mining compared to layered mining.Furthermore,its superior cavern stability presents strong potential for large-scale implementation.
基金supported by the National Natural Science Foundation of China (No. 51404278)the State Key Program of National Natural Science Foundation of China (No. 51134005)
文摘With the third innovation in science and technology worldwide, China has also experienced thismarvelous progress. Concerning the longwall mining in China, the ＂masonry beam theory＂ （MBT） wasfirst proposed in the 1960s, illustrating that the transmission and equilibrium method of overburdenpressure using reserved coal pillar in mined-out areas can be realized. This forms the so-called ＂121mining method＂, which lays a solid foundation for development of mining science and technology inChina. The ＂transfer rock beam theory＂ （TRBT） proposed in the 1980s gives a further understanding forthe transmission path of stope overburden pressure and pressure distribution in high-stress areas. In thisregard, the advanced 121 mining method was proposed with smaller coal pillar for excavation design,making significant contributions to improvement of the coal recovery rate in that era. In the 21st century,the traditional mining technologies faced great challenges and, under the theoretical developmentspioneered by Profs. Minggao Qian and Zhenqi Song, the ＂cutting cantilever beam theory＂ （CCBT） wasproposed in 2008. After that the 110 mining method is formulated subsequently, namely one stope face,after the first mining cycle, needs one advanced gateway excavation, while the other one is automaticallyformed during the last mining cycle without coal pillars left in the mining area. This method can beimplemented using the CCBT by incorporating the key technologies, including the directional presplittingroof cutting, constant resistance and large deformation （CRLD） bolt/anchor supporting systemwith negative Poisson＇s ratio （NPR） effect material, and remote real-time monitoring technology. TheCCBT and 110 mining method will provide the theoretical and technical basis for the development ofmining industry in China.
基金financially supported by the State Key Research Development Program of China(Grant No.2016YFC0600701)the National Natural Science Foundation of China(Grant No.51674170)
文摘In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining （NM）, top-coal caving mining （TCM） and protective coal-seam mining （PCM）, are modeled using discrete element software UDEC, The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields, For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest, The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively, The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM, It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential, The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high- efficiency coal mining,
基金supported by the National Natural Science Foun dation of China(52374170 and 51974313)the National Key Research and Development Plan Project(2022YFF1303300).
文摘1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrestrial ecosystems.
基金supported by the Key Project of the National Natural Science Foundation of China(U23B2091)the National Key R&D Program of China(2022YFC2905600)+1 种基金the Youth Project of the National Natural Science Foundation of China(52304104 and 52404157)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240825).
文摘As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.
基金funded by the National Natural Science Foundation of China (No.52225402)Inner Mongolia Research Institute,China University of Mining and Technology-Beijing (IMRI23003)。
文摘In the gas-coal integrated mining field,the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline's safety requirements.Considering the coal pillar recovery rate and pipeline's safety requirements,two new shaped coal pillar design approaches for subsurface pipelines were developed.Firstly,the deformation limitations for measuring pipeline safety are categorized into two:no deformation is permitted,and deformation is acceptable within elastic limits.Subsequently,integrating the key stratum theory(KST)and cave angle,a fishbone-shaped coal pillar design approach that does not permit pipeline deformation is established.Meanwhile,combined with the ground subsidence and the pipeline's elastic deformation limit,a grille-shaped coal pillar design approach that accepts deformation pipelines within elastic limits is established.Those two new approaches clarify parameters including mined width,coal pillar width and mined length.Finally,the case study shows that the designed mined width,coal pillar width and mined length of the fishbone-shaped coal pillar are 90,80,and 130 m,while those of the grille-shaped are 320,370,and640 m.Compared with the conventional method,the fishbone-shaped and grille-shaped coal pillar design approaches recovered coal pillar resources of 2.65×10~6and 5.81×10~6t on the premise of meeting the pipeline safety requirements,and the recovery rates increased by 20.5%and 45.0%,with expenditures representing only 56.46%and 20.02%of the respective benefits.These new approaches provide managers with diverse options for protecting pipeline safety while promoting coal pillar recovery,which is conducive to the harmonic mining of gas-coal resources.
基金supported by the National Natural Science Foundation of China(Grant Nos.5193400852374106+5 种基金5220416352404159)China Postdoctoral Science Foundation(Grant no.2024T171006)the Fundamental Research Funds for the Central Universities(Grant Nos.2024ZKPYNY042023ZKPYNY012023YQTD02)。
文摘Underground coal mining induces significant surface deformation and environmental damage,particularly in deeply buried mining areas with thin bedrock and thick alluvial layers.Based on the case study of the Zhaogu No.2 coal mine in Xinxiang City,Henan Province,China,this study employs a comprehensive research methodology,integrating field investigations,numerical simulations,and theoretical analyses,to explore the surface subsidence features at deeply buried mining areas with thin bedrock and thick alluvial layers,to reveal the effect of alluvial thickness on the surface subsidence characteristics.The findings indicate that the surface subsidence areas span 4.2 km2 with an advanced influence distance of 540 m.The rate of surface subsidence primarily depends on the panel's position and its advancing rate.Moreover,the thickness of the alluvial layer amplifies both the extent and magnitude of surface deformation.The displacement of overlying rock primarily exhibits a two-stage progression:the thin bedrock control stage and the alluvial control stage.In the thin bedrock control stage,surface subsidence initiates with relatively low subsidence values and amplitudes.Subsequently,in the alluvial control stage,surface subsidence accelerates,leading to a rapid increase in both subsidence values and amplitudes.These characteristics of rock formation displacement result in distinct phases of surface subsidence.Furthermore,the paper addresses the utilization of surface subsidence areas and proposes a method for calculating reservoir storage capacity in these areas.According to calculations,the storage capacity amounts to 1.05e7 m^(3).The research findings provide valuable insights into the surface subsidence laws in regions with similar geological conditions and practical implications for the management and utilization of subsided areas.
基金funded by Guizhou Provincial Science and Technology Project,Qiankehejichu-ZK[2022]-YB529Guizhou Education Department(Youth Science and Technology Topnotch Talent Project)QJJ[2024]345+1 种基金Guizhou Provincial Science and Technology Project,QKHJC-ZK[2023]-YBGuizhou Education Department Youth Science and Technology Talents Growth Project,QJHKY[2020]122.
文摘The complex and diverse nature of coal mining sites,including different landforms and working conditions,presents challenges for rehabilitation efforts.To address this,we conducted a comprehensive experimental study focusing on microbially induced calcium carbonate precipitation(MICP)remediation,considering the fracture characteristics of coal mining sites.The MICP-restored samples were subjected to confined/unconfined compressive strength,uniaxial/triaxial permeability,and souring tests to assess their restoration efficacy.The results showed that under similar mining conditions,the average depth of parallel fractures was 0.185 m for loess ridges,0.16 m for the valley,and 0.146 m for the blown-sand region,while the average depth for boundary fractures was 0.411 m for loess ridges,0.178 m for the valley,and 0.268 m for the blown-sand region.Notably,parallel fractures showed negligible filling in all landforms,whereas boundary fractures in the blown-sand region were completely filled with wind-deposited sand.The valley landform was filled with alluvium and wind-deposited sand,whereas the loess landform was filled with wind-deposited sand and loess.MICP-restored soil samples in all landforms achieved a strength comparable to remolded fracture-free soil samples.Across all landforms,the maximum permeability coefficient of MICP-restored soil samples closely matched that of remolded fracture-free soil samples.Under similar topographic and rainfall conditions MICP restorations scoured 31.3 g on blown-sand region,19.3 g on loess ridges,and 17.6 g on valleys.These research findings provide an experimental foundation for MICP repair of coal mining ground fractures.
基金Project(2024B03017)supported by the Key Research and Development Program Projects of Xinjiang Uygur Autonomous Region,ChinaProjects(52225404,52394192)supported by the National Natural Science Foundation of China。
文摘Aiming at the problem that the distance between the main roadway and the working face in Hudi Coal Industry Panel was more than 100 m,which was still affected by mining,high stress concentration of the roadway,and difficulty of supporting overall convergence of the section,the mechanical characteristics of the core bearing strata of the overlying rock caving in the working face were studied.The correlation mechanism between the overlying rock caving and the deformation and failure of the roadway was analyzed,and the quantitative evaluation index was established to comprehensively analyze different influencing factors.Based on the key strata theory,the mechanical difference transfer model of working face mining and panel roadway deformation and failure was established.It was considered that the difference in fracture morphology was the key to the far-field stress disturbance.The regional stress control technology was proposed to block or reduce the stress transfer,so that the peak stress of the panel main roadway was reduced,and the deformation of the surrounding rock was significantly reduced,which provides a reference value for the roadway support with serious influence of mining roadway.
基金supported in part by the National Natural Science Foundation of China(Nos.52174152 and 52074271)in part by the Xuzhou Basic Research Program Project(No.KC23051)+2 种基金in part by the Shandong Province Technology Innovation Guidance Plan(Central Guidance for Local Scientific and Technological Development Fund)(No.YDZX2024119)in part by the Graduate Innovation Program of China University of Mining and Technology(No.2025WLKXJ088)in part by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX252830).
文摘Rapid and accurate recognition of coal and rock is an important prerequisite for safe and efficient coal mining.In this paper,a novel coal-rock recognition method is proposed based on fusing laser point cloud and images,named Multi-Modal Frustum PointNet(MMFP).Firstly,MobileNetV3 is used as the backbone network of Mask R-CNN to reduce the network parameters and compress the model volume.The dilated convolutional block attention mechanism(Dilated CBAM)and inception structure are combined with MobileNetV3 to further enhance the detection accuracy.Subsequently,the 2D target candidate box is calculated through the improved Mask R-CNN,and the frustum point cloud in the 2D target candidate box is extracted to reduce the calculation scale and spatial search range.Then,the self-attention PointNet is constructed to segment the fused point cloud within the frustum range,and the bounding box regression network is used to predict the bounding box parameters.Finally,an experimental platform of shearer coal wall cutting is established,and multiple comparative experiments are conducted.Experimental results indicate that the proposed coal-rock recognition method is superior to other advanced models.
基金supported by the National Science Fund of China(Grant No.52225402)Fund of Inner Mongolia Research Institute,China University of Mining and Technology(Beijing)(Grant No.IMRI23003).
文摘High-intensive underground mining has caused severe ground fissures,resulting in environmental degradation.Consequently,prompt detection is crucial to mitigate their environmental impact.However,the accurate segmentation of fissuresin complex and variable scenes of visible imagery is a challenging issue.Our method,DeepFissureNets-Infrared-Visible(DFN-IV),highlights the potential of incorporating visible images with infrared information for improved ground fissuresegmentation.DFNIV adopts a two-step process.First,a fusion network is trained with the dual adversarial learning strategy fuses infrared and visible imaging,providing an integrated representation of fissuretargets that combines the structural information with the textual details.Second,the fused images are processed by a fine-tunedsegmentation network,which lever-ages knowledge injection to learn the distinctive characteristics of fissuretargets effectively.Furthermore,an infrared-visible ground fissuredataset(IVGF)is built from an aerial investigation of the Daliuta Coal Mine.Extensive experiments reveal that our approach provides superior accuracy over single-modality image strategies employed in fivesegmentation models.Notably,DeeplabV3+tested with DFN-IV improves by 9.7%and 11.13%in pixel accuracy and Intersection over Union(IoU),respectively,compared to solely visible images.Moreover,our method surpasses six state-of-the-art image fusion methods,achieving a 5.28%improvement in pixel accuracy and a 1.57%increase in IoU,respectively,compared to the second-best effective method.In addition,ablation studies further validate the significanceof the dual adversarial learning module and the integrated knowledge injection strategy.By leveraging DFN-IV,we aim to quantify the impacts of mining-induced ground fissures,facilitating the implementation of intelligent safety measures.
基金financially supported by the National Natural Science Foundation of China(Nos.52225404,12532020,52394192 and 42321002)Key Research and Development Program Projects of Xinjiang Uygur Autonomous Region(No.2024B03017)Doctoral Startup Foundation of Fuyang Normal University,China(No.2025KYQD0124)。
文摘It is of great significance to study the failure mode of mining roadways for safe coal mining.The unconventional asymmetric failure(UAF)phenomenon was discovered in the 9106 ventilation roadway of Wangzhuang coal mine in Shanxi Province.The main manifestation is that the deformation of the roadway on the coal side is much greater than that on the coal pillar side.A comprehensive study was conducted on on-site detection,theoretical analysis,laboratory tests and numerical simulation of the UAF phenomenon.On-site detection shows that the deformation of the coal sidewall can reach 50–80 cm,and the failure zone depth can reach 3 m.The deformation and fracture depth on the coal pillar side are much smaller than those on the coal side.A calculation model for the principal stress of surrounding rock when the axial direction of the roadway is inconsistent with the in-situ stress field was established.The distribution of the failure zone on both sides of the roadway has been defined by the combined mining induced stress.The true triaxial test studied the mechanical mechanism of rock mass fracture and crack propagation on both sides of the roadway.The research results indicate that the axial direction,stress field distribution,and mining induced stress field distribution of the roadway jointly affect the asymmetric failure mode of the roadway.The angle between the axis direction of the roadway and the maximum horizontal stress field leads to uneven distribution of the principal stress field on both sides.The differential distribution of mining induced stress exacerbates the asymmetric distribution of principal stress in the surrounding rock.The uneven stress distribution on both sides of the roadway is the main cause of UAF formation.The research results can provide mechanical explanations and theoretical support for the control of surrounding rock in roadways with similar failure characteristics.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907501)the National Natural Science Foundation of China(No.52374106)+1 种基金the China Postdoctoral Science Foundation(Grant no.2024T171006)the National Natural Science Foundation of China(Grant no.52204163).
文摘Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three focused works to address this problem.Firstly,field measurements were conducted to clarify rib spalling characteristics:the coal wall is dominated by shear failure,internal cracks are mainly distributed 3–6 m above the coal wall surface,and the maximum depth of crack development reaches 3 m.Secondly,Universal Distinct Element Code(UDEC)numerical simulation software was used to build a rib spalling model,with the Trigon model adopted to divide the coal wall into blocks.Analysis of four key factors shows that increased buried depth and mining height significantly raise the total length of coal wall internal cracks,increasing rib spalling risk,while higher coal body strength and support strength effectively alleviate this phenomenon.Finally,an orthogonal experiment was designed to quantitatively determine the influence degree of the four factors on rib spalling.Results show that coal body strength has the greatest impact,followed by support strength,mining height,and mining depth in order of influence.This study provides valuable theoretical guidance for on-site prevention and control of coal wall rib spalling.
文摘The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affects strata movement characteristics,a physical model experiment was conducted based on the geological conditions of the Panel 122104 in Caojiatan Coal Mine in Shaanxi.The experiment examined strata movement at mining heights of 1 m and 10 m,identifying differences in detachment,collapse behavior,and collapse angles under these two conditions.The results indicate the following:Delamination range directly governs collapse patterns,with higher stress concentration accelerating delamination initiation and expanding affected zones.1 m mining height exhibits a“superposed fixed beam”structure with lower strength compared to the“fixed beam+cantilever beam”configuration under 10 m height.A model estimating collapse step shows 9.13%average error.Strata structure dictates collapse angle mechanisms:Pseudo-plastic deformation under 1 m height determines collapse angle through vertical tensile stress boundaries,whereas 10 m height exhibits brittle fracture behavior with collapse angles approximating fracture angles.Periodic collapse volume above working face directly correlates with mine pressure intensity and is positively correlated with the caving step distance,collapse angle,and caving range.These parameters show higher values under 10 m mining height,resulting in more pronounced mine pressure manifestations compared to 1 m conditions.
基金supported by the National Natural Science Foundation of China(No.12071047,51774289,52074291).
文摘To ameliorate the difficulties of on-site dynamic disaster control in the end-mining stage of traditional mining engineering,this paper introduces the mathematical research and engineering application of the end-mining technology system with non-pillar in mines(ETSNM)in recent years.The petal warning criterion for the stability of the surrounding rock of the roadway at the end-mining stage was obtained by studying the inverse problem of the petal theorem.A conformal mathematical model of the end-mining stage was established using the conformal mapping method,and the limit theorem of the peak point of mine pressure(LTPPMP)in the end-mining stage was demonstrated.Based on the cross-fusion of the above basic mathematical theory and the LTPPMP,a new ETSNM model was proposed,which includes no coal pillar,no dedicated retracement roadways,and fast retracement equipment(NNF).The mathematical principles of engineering technology for height control,speed limit,and roof cutting in the end-mining stage with non-pillar were revealed.The scientific and application values of the ETSNM were confirmed through engineering applications.Based on this,a new non-pillar control technology for dynamic disasters in the end-mining stage was proposed.The above research will play an active role in promoting the engineering application of ETSNM driven by mathematical theory.
基金supported by the National Natural Science Foundation of China(Nos.U23B2091,52304104,and 52404157)the National Key R&D Program of China(No.2022YFC2905600)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZB20240825).
文摘Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.
基金financially supported by the Independent Research fund of Joint National Local Engineering Research Centre for Safe and Precise Coal Mining(Anhui University of Science and Technology)(Grant No.EC2022001)State Key Research Development Program of China(Grant No.2022YFC3004602)the Fundamental Research Funds for the Central Universities(Grant No.2022YJSLJ08).
文摘Understanding dynamic visualization of mining-induced stress is of great significance to disaster prevention and control in coal mining activities.In this study,three theoretical models,including linear,polynomial,and exponential models,are proposed to inverse the mining-induced stress through the acquisition and analysis of hydraulic support stress and micro-seismicity in the coal mining face.The distribution of mining-induced stress in the coal seam are graphed by fitting two key stress parameters including hydraulic support stress and peak stress,and two key zones including goaf zone and in situ stress zone.These key stress parameters and zones are defined based on the critical nodes of the model curve.According to the geological background of Mataihao coal mine in Erdos,Inner Mongolia Autonomous Region,China,the contours of mining-induced stress are graphed through the stress calculation of these three inversion theoretical models.The multi-monitoring data of micro-seismicity,drilling chips,advanced borehole stress and bolts axial force are used to verify the key stress parameters and zones of the theoretical models.It shows that the monitoring data are in good agreement with the distribution of inversed results.It should be emphasized that,if the fault structure exists around the mining face,the mining-induced stress decreases obviously when the mining face is passing through the faults,and the location of the peak stress will be closer to the mining face.The results in this study could provide methods for early prevention of extreme mining-induced stress and disaster control in the mining activities.
基金supported by the Major Project of Hunan Natural Science Foundation,China(No.2021JC0010)the National Natural Science Foundation of China(No.51274251)。
文摘The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.
