When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highwa...When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highway construction.Combining three-dimensional physical model tests,numerical simulations and field monitoring,with the Urumqi East Second Ring Road passing through acute inclined goafs as a background,the deformation and failure mechanism of the overlying rock and coal pillars in acute inclined goafs under expressway load were studied.And in accordance with construction requirements of subgrade,comprehensive consideration of the deformation and instability mechanism of acute inclined goafs,the treatment measures and suggestions for this type of geological disasters were put forward.The research results confirmed the rationality of coal pillars in acute inclined goafs under the expressway through grouting.According to the ratio of diff erent overlying rock thickness to coal pillar height,the change trend and value of the required grouting range were summarized,which can provide reference for similar projects.展开更多
The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains lar...The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.展开更多
China has a long history of coal mining,among which open-pit coal mines have a large number of small coal mine goafs underground.The distribution,shape,structure and other characteristics of goafs are isolated and dis...China has a long history of coal mining,among which open-pit coal mines have a large number of small coal mine goafs underground.The distribution,shape,structure and other characteristics of goafs are isolated and discontinuous,and there is no definite geological law to follow,which seriously threatens the safety of coal mine production and personnel life.Conventional ground geophysical methods have low accuracy in detecting goaf areas affected by mechanical interference from open-pit mines,especially for waterless goaf areas,which cannot be detected by existing methods.This article proposes the use of high-frequency electromagnetic waves for goaf detection.The feasibility of using drilling radar to detect goaf was theoretically analyzed,and a goaf detection model was established.The response characteristics of different fillers in the goaf under different frequencies of high-frequency electromagnetic waves were simulated and analyzed.In a certain open-pit mine in Inner Mongolia,100MHz high-frequency electromagnetic waves were used to detect the goaf through directional drilling on the ground.After detection,excavation verification was carried out,and the location of one goaf detected was verified.The results of engineering practice show that the application of high-frequency electromagnetic waves in goaf detection expands the detection radius of boreholes,has the advantages of high efficiency and accuracy,and has important theoretical and practical significance.展开更多
China,as the world’s largest coal producer and consumer,faces increasingly severe challenges from coal mine goaf areas formed through decades of intensive mining.These underground voids,resulting from exhausted resou...China,as the world’s largest coal producer and consumer,faces increasingly severe challenges from coal mine goaf areas formed through decades of intensive mining.These underground voids,resulting from exhausted resources or technical limitations,not only cause environmental issues like land subsidence and groundwater contamination but also pose critical safety risks for ongoing mining operations,including water inrushes,gas outbursts,and roof collapses.Conventional geophysical methods such as seismic surveys and electromagnetic detection demonstrate limited effectiveness in complex geological conditions due to susceptibility to electrical heterogeneity,electromagnetic interference,and interpretation ambiguities.This study presents an innovative integrated approach combining the Audio-Frequency Electrical Transillumination(AFET)method with multi-parameter borehole logging to establish a three-dimensional detection system.The AFET technique employs 0.1–10 kHz electromagnetic waves to identify electrical anomalies associated with goafs,enabling extensive horizontal scanning.This is complemented by vertical high-resolution profiling through borehole measurements of resistivity,spontaneous potential,and acoustic velocity.Field applications in Shanxi Province’s typical coal mines achieved breakthrough results:Using a grid-drilling pattern(15 m spacing,300 m depth),the method successfully detected three concealed goafs missed by conventional approaches,with spatial positioning errors under 0.5 m.Notably,it accurately identified two un-collapsed water-filled cavities.This surface-borehole synergistic approach overcomes single-method limitations,enhancing goaf detection accuracy to over 92%.The technique provides reliable technical support for safe mining practices and represents significant progress in precise detection of hidden geological hazards in Chinese coal mines,offering valuable insights for global mining geophysics.展开更多
Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting i...Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.展开更多
The potential for CO_(2)sequestration in the goaf of abandoned coal mines is significant due to the extensive fracture spaces and substantial residual coal present.Firstly,the adsorption characteristics of residual co...The potential for CO_(2)sequestration in the goaf of abandoned coal mines is significant due to the extensive fracture spaces and substantial residual coal present.Firstly,the adsorption characteristics of residual coal in goaf on CO_(2)were studied by the isothermal adsorption test of CO_(2).Then,to accurately calculate the amount of adsorbed CO_(2)within the residual coal in the goaf,the bidisperse diffusion numerical model considering only Fick diffusion was modified in combination with the diffusion mechanisms.The simulation results showed that the modified model can well describe the diffusion behavior of CO_(2)in the residual coal matrix.Finally,the numerical simulation of CO_(2)sequestration in the goaf of abandoned coal mines was carried out,and the influence of different injection well deployment positions and various thicknesses of residual coal on the migration law and storage effect of CO_(2)in goaf was analyzed.The results showed that CO_(2)preferentially flowed into the caving zone with higher permeability.The distribution of CO_(2)streamlines in the goaf was the most dense in the caving zone and the streamlines in the fracture zone were gradually sparse from bottom to top.When the injection well was deployed at the interface of the two zones,the CO_(2)had the best seepage path.The total storage capacity within90 days was 7.702754×10^(6)kg,of which the free state storage capacity in the fracture of the goaf and the adsorbed state storage capacity in the residual coal were 6.611451×10^(6)and 1.091303×10^(6)kg,respectively.When the injection well was deployed in the middle of the residual coal seam in the goaf and the middle of the fracture zone,the total storage capacity at the same time was 7.613508×10^(6)and 6.021495×10^(6)kg,respectively.The coal with different thicknesses remaining at the bottom of the goaf significantly affected the adsorbed state storage,but had little effect on the free state storage.When the thickness of the residual coal seam was 0.20,0.35,and 0.50 m,the adsorbed state storage capacity within 130 days was 4.37623×10^(5),7.65791×10^(5),and 1.093406×10^(6)kg,respectively.展开更多
A Bayes discriminant analysis method to identify the risky of complicated goaf in mines was presented. Nine factors influencing the stability of goaf risky, including uniaxial compressive strength of rock, elastic mod...A Bayes discriminant analysis method to identify the risky of complicated goaf in mines was presented. Nine factors influencing the stability of goaf risky, including uniaxial compressive strength of rock, elastic modulus of rock, rock quality designation （RQD）, area ratio of pillar, ratio of width to height of pillar, depth of ore body, volume of goaf, dip of ore body and area of goal, were selected as discriminant indexes in the stability analysis of goal. The actual data of 40 goals were used as training samples to establish a discriminant analysis model to identify the stability of goaf. The results show that this discriminant analysis model has high precision and misdiscriminant ratio is 0.025 in re-substitution process. The instability identification of a metal mine was distinguished by using this model and the identification result is identical with that of practical situation.展开更多
An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, clo...An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.展开更多
基金Science and Technology Major Project of Xinjiang Uygur Autonomous Region(2020A03003-7)Fundamental Research on Natural Science Program of Shaanxi Province(2021JM-180)+2 种基金Fundamental Research Funds for the Central Universities,CHD(Project for Leading Talents)(300102211302)Tianshan Cedar Plan of Science and Technology Department of Xinjiang Uygur Autonomous Region(2017XS13)Shaanxi Province Young Talent Lifting Program(CLGC202219).
文摘When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highway construction.Combining three-dimensional physical model tests,numerical simulations and field monitoring,with the Urumqi East Second Ring Road passing through acute inclined goafs as a background,the deformation and failure mechanism of the overlying rock and coal pillars in acute inclined goafs under expressway load were studied.And in accordance with construction requirements of subgrade,comprehensive consideration of the deformation and instability mechanism of acute inclined goafs,the treatment measures and suggestions for this type of geological disasters were put forward.The research results confirmed the rationality of coal pillars in acute inclined goafs under the expressway through grouting.According to the ratio of diff erent overlying rock thickness to coal pillar height,the change trend and value of the required grouting range were summarized,which can provide reference for similar projects.
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20242059)the Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province(PCMGH-2023-02)the opening fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105827-FW202209)are gratefully acknowledged.
文摘The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.
文摘China has a long history of coal mining,among which open-pit coal mines have a large number of small coal mine goafs underground.The distribution,shape,structure and other characteristics of goafs are isolated and discontinuous,and there is no definite geological law to follow,which seriously threatens the safety of coal mine production and personnel life.Conventional ground geophysical methods have low accuracy in detecting goaf areas affected by mechanical interference from open-pit mines,especially for waterless goaf areas,which cannot be detected by existing methods.This article proposes the use of high-frequency electromagnetic waves for goaf detection.The feasibility of using drilling radar to detect goaf was theoretically analyzed,and a goaf detection model was established.The response characteristics of different fillers in the goaf under different frequencies of high-frequency electromagnetic waves were simulated and analyzed.In a certain open-pit mine in Inner Mongolia,100MHz high-frequency electromagnetic waves were used to detect the goaf through directional drilling on the ground.After detection,excavation verification was carried out,and the location of one goaf detected was verified.The results of engineering practice show that the application of high-frequency electromagnetic waves in goaf detection expands the detection radius of boreholes,has the advantages of high efficiency and accuracy,and has important theoretical and practical significance.
文摘China,as the world’s largest coal producer and consumer,faces increasingly severe challenges from coal mine goaf areas formed through decades of intensive mining.These underground voids,resulting from exhausted resources or technical limitations,not only cause environmental issues like land subsidence and groundwater contamination but also pose critical safety risks for ongoing mining operations,including water inrushes,gas outbursts,and roof collapses.Conventional geophysical methods such as seismic surveys and electromagnetic detection demonstrate limited effectiveness in complex geological conditions due to susceptibility to electrical heterogeneity,electromagnetic interference,and interpretation ambiguities.This study presents an innovative integrated approach combining the Audio-Frequency Electrical Transillumination(AFET)method with multi-parameter borehole logging to establish a three-dimensional detection system.The AFET technique employs 0.1–10 kHz electromagnetic waves to identify electrical anomalies associated with goafs,enabling extensive horizontal scanning.This is complemented by vertical high-resolution profiling through borehole measurements of resistivity,spontaneous potential,and acoustic velocity.Field applications in Shanxi Province’s typical coal mines achieved breakthrough results:Using a grid-drilling pattern(15 m spacing,300 m depth),the method successfully detected three concealed goafs missed by conventional approaches,with spatial positioning errors under 0.5 m.Notably,it accurately identified two un-collapsed water-filled cavities.This surface-borehole synergistic approach overcomes single-method limitations,enhancing goaf detection accuracy to over 92%.The technique provides reliable technical support for safe mining practices and represents significant progress in precise detection of hidden geological hazards in Chinese coal mines,offering valuable insights for global mining geophysics.
基金supported by the National Natural Science Foundation of China(U21A20321 and 22378241)Research Project Supported by Shanxi Scholarship Council of China(2024-015).
文摘Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:2024KYJD1012。
文摘The potential for CO_(2)sequestration in the goaf of abandoned coal mines is significant due to the extensive fracture spaces and substantial residual coal present.Firstly,the adsorption characteristics of residual coal in goaf on CO_(2)were studied by the isothermal adsorption test of CO_(2).Then,to accurately calculate the amount of adsorbed CO_(2)within the residual coal in the goaf,the bidisperse diffusion numerical model considering only Fick diffusion was modified in combination with the diffusion mechanisms.The simulation results showed that the modified model can well describe the diffusion behavior of CO_(2)in the residual coal matrix.Finally,the numerical simulation of CO_(2)sequestration in the goaf of abandoned coal mines was carried out,and the influence of different injection well deployment positions and various thicknesses of residual coal on the migration law and storage effect of CO_(2)in goaf was analyzed.The results showed that CO_(2)preferentially flowed into the caving zone with higher permeability.The distribution of CO_(2)streamlines in the goaf was the most dense in the caving zone and the streamlines in the fracture zone were gradually sparse from bottom to top.When the injection well was deployed at the interface of the two zones,the CO_(2)had the best seepage path.The total storage capacity within90 days was 7.702754×10^(6)kg,of which the free state storage capacity in the fracture of the goaf and the adsorbed state storage capacity in the residual coal were 6.611451×10^(6)and 1.091303×10^(6)kg,respectively.When the injection well was deployed in the middle of the residual coal seam in the goaf and the middle of the fracture zone,the total storage capacity at the same time was 7.613508×10^(6)and 6.021495×10^(6)kg,respectively.The coal with different thicknesses remaining at the bottom of the goaf significantly affected the adsorbed state storage,but had little effect on the free state storage.When the thickness of the residual coal seam was 0.20,0.35,and 0.50 m,the adsorbed state storage capacity within 130 days was 4.37623×10^(5),7.65791×10^(5),and 1.093406×10^(6)kg,respectively.
基金Project (2010CB732004) supported by the National Basic Research Program of China
文摘A Bayes discriminant analysis method to identify the risky of complicated goaf in mines was presented. Nine factors influencing the stability of goaf risky, including uniaxial compressive strength of rock, elastic modulus of rock, rock quality designation （RQD）, area ratio of pillar, ratio of width to height of pillar, depth of ore body, volume of goaf, dip of ore body and area of goal, were selected as discriminant indexes in the stability analysis of goal. The actual data of 40 goals were used as training samples to establish a discriminant analysis model to identify the stability of goaf. The results show that this discriminant analysis model has high precision and misdiscriminant ratio is 0.025 in re-substitution process. The instability identification of a metal mine was distinguished by using this model and the identification result is identical with that of practical situation.
基金Project(51274250)supported by the National Natural Science Foundation of ChinaProject(2012BAK09B02-05)supported by the National Key Technology R&D Program during the 12th Five-year Plan of China
文摘An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.
