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Understanding of mineral change mechanisms in coal mine groundwater reservoir and their influences on effluent water quality:a experimental study

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International Journal of Coal Science & Technology 2021年第1期8卷 154-167页

作者： Kai Zhang Huifang Li Jiaming Han Binbin Jiang Ju Gao School of Chemical and Environmental Engineering China University of Mining and TechnologyBeijingBeijing100083China State Key Laboratory of Water Resource protection and Utilization in Coal mining Beijing102211China

This paper presents results of an experimental study to characterize the law of mineral change of fallen rock in coal mine groundwater reservoir ant its influence on water *** minerals of the underground reservoir of Daliuta Coal Mine is taken as the research *** experiments were designed and conducted to simulate water–rock action in the *** mineral composition was analyzed by X-ray diffractometer(XRD),the surface morphology of the mineral was analyzed by scanning electron microscope(SEM),and the specific surface area,total pore volume and average pore diameter of the mineral were measured by fast specific surface/pore analyzer(BET).The experimental results show that the sandstone and mudstone in the groundwater reservoir of Daliuta Coal Mine account for 70%and 30%,*** pore diameter is 15.62–17.55 nm,and pore volume is 0.035 cc/*** pore structure is a key factor in the occurrence of water–rock *** to the water–rock simulation experiment,the quartz content before the water–rock action is about 34.28%,the albite is about 21.84%,the feldspar is about 17.48%,and the kaolinite is about 8.00%.After the water–rock action,they are 36.14%,17.78%,11.62%,and 16.75%,*** content of albite and orthoclase is reduced while the content of kaolinite is increased,that is,the Na+content becomes higher,and the Ca2+and Mg2+contents become *** research builds a good theoretical foundation for revealing the role of water and rock in underground coal reservoirs.

关键词： Coal mine underground reservoir Fallen rock Water-rock interaction Rock composition

Bearing characteristics of coal pillars based on modified limit equilibrium theory

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International Journal of mining Science and Technology 2015年第6期25卷 943-947页

作者： Wang Xiangyu Bai Jianbiao Wang Ruofan Sheng Wenlong School of Mines Key Laboratory of Deep Coal Resource Mining Ministry of Education of China China University of Mining & Technology State Key Laboratory of Coal Resources and Mine safety China University of Mining & Technology

There are two states for the coal-mass on the goal-side which is in stress equilibrium： the state of limit equilibrium （the bearing stress in the coal-mass equals its ultimate bearing stress） and the state of non- ultimate equilibrium （the bearing stress in the coal-mass is less than its ultimate bearing stress）. To ana- lyze the bearing characteristics of a coal pillar in the state of limit equilibrium and guide the design of pillar width, we established a mechanical analytical model of the non-ultimate equilibrium zone in the coal-mass on the goal-side combined with the limit equilibrium theory as well as adopting the methods of theory analysis and mechanical analysis based on the assumption of a state of non-ultimate equilibrium. The width correction coeffident of the limit equilibrium zone has been given. The influence of mining depth, stress concentration coefficient of the surrounding rock, the non-limit strength of the coal-mass and stability of the coal rock interface has been studied. On this basis, we have confirmed that when the width ofa longwall mining face roadway protection coal pillar is between 11.6 m and 13.16 m in No. 4 coal seam of Xinrui coal mine in Lvliang in Shanxi province the elastic core region in the coal pillar can be assured and the roadway will be located in the area of lower stress which is outside the peak stress. So the revised width of the limit eauilibrium zone is more oractical.

关键词： Coal bearingZone of non-ultimate equilibriumWidth correction coefficient of plastic zoneWidth of roadway protection pillar

Performance of N95 elastomeric respirators in high humidity and high coal dust concentration environment

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International Journal of mining Science and Technology 2022年第1期32卷 215-224页

作者： Jintuo Zhu Xinjian He Liang Wang Xiaoxue Liao Guangping Teng Pengli Jing Key Laboratory of Gas and Fire Control for Coal Mines(China University of mining and Technology) Ministry of EducationXuzhou 221116China National Professional Laboratory for Fundamental Research of Mine Gas and Dust Control Technology School of Safety EngineeringChina University of Mining and TechnologyXuzhou 221116China School of safety Engineering China University of Mining and TechnologyXuzhou 221116China

High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal *** paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of *** on the self-designed in-situ PM2.5 collector,controllable PM2.5 generator,human breathing simulator,and respirator simulation testing system,under the simulated deep mine working condition,this study investigated the effects of dust loading,wearing time,and dust concentration on the filtration efficiency,breathing resistance,and quality factor of N95 elastomeric *** the increase of dust loading,the respirator filtration efficiency firstly decreased,then increased(minimum value 97.5%).The breathing resistance increased exponentially from 120 to 180 to 1020-1530 Pa,and the quality factor decreased logarithmically from 0.051 to 0.076 to 0.0058-0.0085 Pa^(-1).As the PM2.5 coal dust concentration increased from 5 to 50 mg/m^(3),the wearing time for the respirator breathing resistance to exceed 300 Pa reduced from 7 h to less than 1 *** N95 elastomeric respirator is not able to perform an 8-h work *** avoid the excessive breathing resistance caused by dust loading,more filter cartridges are needed for coal miners.

关键词： Coal dust Respirator Dust loading Filtration efficiency Breathing resistance

Mechanical behavior of micaceous clays

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第5期11卷 1044-1054页

作者： Jiahe Zhang Amin Soltani An Deng Mark B.Jaksa School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaideSA 5005Australia Department of infrastructure Engineering The University of MelbourneParkvilleVIC 3010Australia

This study aims to investigate the effect of mica content on the mechanical properties of *** available ground mica was blended with a locally available clayey soil,at varying mica contents by mass of 5%,10%,15%,20%,25%and 30%,to artificially prepare various micaceous clay *** preliminary testing phase included consistency limits and standard Proctor compaction *** primary testing program consisted of unconfined compression(UC),direct shear(DS)and scanning electron microscopy(SEM)*** test results showed that the liquid and plastic limits exhibited a linear,monotonically increasing trend with increase in mica *** rate of increase in the plastic limit,however,was found to be greater than that of the liquid limit,thereby leading to a gradual transition towards a non-plastic,cohesionless *** soft,spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica *** low confinement conditions,*** UC test and the DS test at low normal stresses,the shear strength was adversely affected by ***,the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface,thus leading to improved strength resistance.

关键词： Micaceous clay Mica content Consistency limits Compaction Shear strength Confinement Frictional resistance

Dynamic tensile behaviour and crack propagation of coal under coupled static-dynamic loading

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International Journal of mining Science and Technology 2020年第5期30卷 659-668页

作者： Xianjie Hao Weisheng Du Yixin Zhao Zhuowen Sun Qian Zhang Shaohua Wang Haiqing Qiao Beijing Key Laboratory for Precise mining of Inter-grown Energy and Resources China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Water Resource protection and Utilization in Coal mining Beijing 100083China State Key Laboratory of Coal Resources and Safe mining China University of Mining and Technology-BeijingBeijing 100083China School of Energy and mining Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The fracture behaviour and crack propagation features of coal under coupled static-dynamic loading conditions are important when evaluating the dynamic failure of *** this study,coupled static-dynamic loading tests are conducted on Brazilian disc(BD)coal specimens using a modified split Hopkinson pressure bar(SHPB).The effects of the static axial pre-stress and loading rate on the dynamic tensile strength and crack propagation characteristics of BD coal specimens are *** average dynamic indirect tensile strength of coal specimens increases first and then decreases with the static axial pre-stress *** no static axial pre-stress is applied,or the static axial pre-stress is 30%of the static tensile strength,the dynamic indirect tensile strength of coal specimens shows an increase trend as the loading rate *** the static axial pre-stress is 60%of the static tensile strength,the dynamic indirect tensile strength shows a fluctuant trend as the loading rate *** to the crack propagation process of coal specimens recorded by high-speed camera,the impact velocity influences the mode of crack propagation,while the static axial pre-stress influences the direction of crack *** failure of coal specimens is a coupled tensile-shear failure under high impact *** there is no static axial pre-stress,tensile cracks occur in the vertical loading *** the static axial pre-stress is applied,the number of cracks perpendicular to the loading direction decreases,and more cracks occur in the parallel loading direction.

关键词： Coal Coupled static-dynamic loading SHPB Dynamic fracture behaviour Crack propagation

Relationships between gas reservoir and the evolution of stope surrounding rock fracture at the process of mining the closed distance protection layer

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mining Science and Technology 2009年第5期19卷 653-656页

作者： HAO Zhi-yong LIN Bai-quan WU Hai-jin MENG Jie School of safety Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

Overburden rock movements and fracture developments occur during mining activities. Consequently, relief gas reservoirs and migration in coal seams being mined as well as in near distant coal seams appear. We considered a gas disaster management project and rules on stope relief of gas flows together and explored a gas reservoir and the evolution of stope surrounding rock fractures in the process of mining near distant protective layers by physical simulation, numerical simulation and field testing. Different techniques provide evidence of the rules of interaction of gas reservoirs and the evolution of surrounding rock fractures and are able to find accurately the gas-rich regions around the stope. Finally, we found that these rules can provide a basis for taking measures to prevent gas accidents in the protective layer of the coalface as well as for demonstrating and designing programs to drain high concentrations of gas from the gob.

关键词： physical simulation numerical simulation gas reservoir evolution of fractures

Effectiveness of coal mine dust control:A new technique for preparation and efficacy of self-adaptive microcapsule suppressant

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International Journal of mining Science and Technology 2022年第6期32卷 1181-1196页

作者： Bo Ren Liang Yuan Gang Zhou Shuailong Li Qunzhi Meng Kai Wang Bingyou Jiang Guofeng Yu School of Emergency Management and safety Engineering China University of Mining and Technology–BeijingBeijing 100083China State Key Laboratory of Deep Coal mining&Environment protection Huainan Mining Group Co.LTD.Huainan 232001China Key Laboratory of Industrial Dust Control and Occupational Health Ministry of EducationAnhui University of Science and TechnologyHuainan 232001China College of safety and Environmental Engineering Shandong University of Science and TechnologyQingdao 266590China Department of Civil and Environmental Engineering University of AlbertaEdmonton T6G 2R3Canada

This study aims to make full use of the agricultural waste peanut shells to lower material costs and achieve cleaner production at the same *** nanofibrils(CNF)extracted from peanut shells were mixed with acrylic acid(AA)and dimethyl diallyl ammonium chloride(DMDAAC)to prepare a new type of capsule core(dust suppressant).Then,the self-adaptive AA-DM-CNF/CA microcapsules were prepared under the action of calcium *** infrared spectroscopy and X-ray diffraction analysis results suggest that AA,DMDAAC and CNF have experienced graft copolymerization which leads to the formation of an amorphous *** scanning electron microscopy analysis results demonstrate that the internal dust suppressant can expand and break the wall after absorbing water,featuring a self-adaptive ***,the laser particle size analysis results show that the microcapsules,inside which the encapsulated dust suppressant can be observed clearly,maintain a good *** product performance experimental results reveal that the capsule core and the capsule wall achieve synergistic dust suppression,thus lengthening the dust suppression *** product boasts good dust suppression,weather resistance,degradation and synergistic combustion ***,this study,as the first report on the development and analysis of dust-suppressing microcapsules,fills in the research gap on the reaction mechanism between dust-suppressing microcapsules and coal by MS *** proposed AA-DM-CNF/CA dust-suppressing microcapsules can effectively lower the dust concentration in the space and protect the physical and mental health of coal *** general,this research provides a new insight into the structure control and performance enhancement of dust *** the application range of microcapsules is of crucial economic and social benefits.

关键词： Waste peanut shell AA-DM-CNF/CA Self-adaptive Dust suppression microcapsule Molecular dynamics simulation

Simulation of multi-support depth-varying earthquake ground motions within heterogeneous onshore and offshore sites

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 475-490页

作者： Li Chao Li Hongnan Hao Hong Bi Kaiming Tian Li State Key Laboratory of Coastal and Offshore Engineering Faculty of Infrastructure EngineeringDalian University of Technology School of Civil Engineering Shenyang Jianzhu University Center for infrastructure Monitoring and protection School of Civil and Mechanical EngineeringCurtin University School of Civil Engineering Guangzhou University School of Civil Engineering Shandong University

This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions（MDSMs） within heterogeneous offshore and onshore *** on 1 D wave propagation theory,the three-dimensional ground motion transfer functions on the surface or within an offshore or onshore site are derived by considering the effects of seawater and porous soils on the propagation of seismic P ***,the depth-varying and spatial variation properties of seismic ground motions are considered in the ground motion *** the obtained transfer functions at any locations within a site,the offshore or onshore depth-varying seismic motions are stochastically simulated based on the spectral representation method（SRM）.The traditional approaches for simulating spatially varying ground motions are improved and extended to generate MDSMs within multiple offshore and onshore *** simulation results show that the PSD functions and coherency losses of the generated MDSMs are compatible with respective target values,which fully validates the effectiveness of the proposed simulation *** synthesized MDSMs can provide strong support for the precise seismic response prediction and performance-based design of both offshore and onshore large-span engineering structures.

关键词： seismic motion simulation onshore and offshore sites ground motion spatial variation depth-varying motions transfer function

Development of an improved three-dimensional rough discrete fracture network model:Method and application

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International Journal of mining Science and Technology 2023年第12期33卷 1469-1485页

作者： Peitao Wang Chi Ma Bo Zhang Qi Gou Wenhui Tan Meifeng Cai Key Laboratory of Ministry of Education for Efficient mining and safety of Metal Mine University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Water Resource protection and Utilization in Coal mining CHN Energy Shendong Coal Group Co.Ltd.Beijing 102201China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China

Structure plane is one of the important factors affecting the stability and failure mode of rock mass *** mass structure characterization is the basic work of rock mechanics research and the important content of numerical simulation.A new 3-dimensional rough discrete fracture network(RDFN3D)model and its modeling method based on the Weierstrass-Mandelbrot(W-M)function were presented in this *** RDFN3D model,which improves and unifies the modelling methods for the complex structural planes,has been *** influence of fractal dimension,amplitude,and surface precision on the modeling parameters of RDFN3D was *** reasonable W-M parameters suitable for the roughness coefficient of JRC were proposed,and the relationship between the mathematical model and the joint characterization was *** RDFN3D together with the smooth 3-dimensional discrete fracture network(DFN3D)models were successfully exported to the drawing exchange format,which will provide a wide application in numerous numerical simulation codes including both the continuous and discontinuous *** numerical models were discussed using the COMSOL Multiphysics code and the 3-dimensional particle flow code,*** reliability of the RDFN3D model was preliminarily discussed and *** roughness and spatial connectivity of the fracture networks have a dominant effect on the fluid flow *** research results can provide a new geological model and analysis model for numerical simulation and engineering analysis of jointed rock mass.

关键词： Jointed rock mass Discrete fracture network Roughness Weierstrass-Mandelbrot function 3D modeling Rock mechanics