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国际煤炭科学技术学报（英文）
国际煤炭科学技术学报（英文）

季刊

2095-8293

国际煤炭科学技术学报（英文）/Journal International Journal of Coal Science & TechnologyCSCDCSTPCD北大核心
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收录年代

    Mechanism of rockburst induced by the microseismic event in the floor strata of high tectonic stress zones:A case study

    Songwei WangAnye CaoChangbin WangWenhao Guo...
    1-15页
    查看更多>>摘要：With the increase of mining scope,rockburst occurs frequently,but its generation mechanism has not been understood comprehensively.Based on a rockburst in the coal pillar area of high tectonic stress zones(HTSZs),this study analyzed the distribution characteristics of large-energy microseismic(MS)events by using data statistics.The mechanical cause of the MS event that induced the rockburst was revealed by means of seismic moment tensor inversion.On this basis,by using numerical simulation,this study explored the distribution characteristics of static load in rockburst area and the effect of dynamic load in the floor,and then proposed the rockburst mechanism.The results show that under the squeez-ing action,the floor strata in HTSZs implode and transmit energy outward in the form of stress waves.This causes the cumulative damage and stress of the coal body in the fast track of coal pillar area increase in a short time.Since the coal in this area has already been in the critical stress state,small stress changes may lead to coal failure and rockburst.In this case of rockburst,the high static load of coal is the main force source,and the dynamic load plays a role in increasing coal body damage and inducing rockburst.Combined with seismic moment tensor inversion and numerical simulation,this paper proposes a rockburst research scheme,which makes the simulation of dynamic load more reasonable.The results provide the theoretical basis for rockburst control under similar conditions.
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    Shear mechanical behavior and fracturing path of red sandstone treated by joninted effect of water-fractures

    Yangyang LiHuicong ZhuShichuan ZhangBing Chen...
    16-28页
    查看更多>>摘要：Water content and primary fractures can change the mechanical characteristics of rock,making it easy to induce geological disasters.Therefore,direct shear tests of red sandstone under the action of water-fracture were carried out in this paper.The results show that shear strength of rock samples with fractures is less than that of intact rock samples.With the increase of primary fracture dip angle,shear strength and macroscopic crushing area of the rock sample increases first and then decreases with 20° as the boundary.It shows that the primary fractures weaken the shear mechanical properties and change the mac-roscopic failure mode.The shear performance of water-bearing rock samples is weaker than that of intact rock samples,and the weakening degree of water-saturated on shear performance of rock samples is lower than that of unsaturated water state.The fracture surfaces of rock samples are divided into'shortest path single through type','longest path single through type'and'cross path through type'.The failured rock samples are divided into'single through type'and'cross through type'.The research results can provide reference for geological disaster management under relevant conditions.
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    Coupled THMC model-based prediction of hydraulic fracture geometry and size under self-propping phase-transition fracturing

    Nanlin ZhangFushen LiuLiangliang JiangPinqiang Mo...
    29-53页
    查看更多>>摘要：The Self-Propping Phase-transition Fracturing Technology(SPFT)represents a novel and environmentally friendly approach for a cost-effective and efficient development of the world's abundant unconventional resources,especially in the context of a carbon-constrained sustainable future.SPFT involves the coupling of Thermal,Hydraulic,Mechanical,and Chemical(THMC)fields,which makes it challenging to understand the mechanism and path of hydraulic fracture propagation.This study addresses these challenges by developing a set of THMC multifield coupling models based on SPFT parameters and the physical/chemical characteristics of the Phase-transition Fracturing Fluid System(PFFS).An algorithm,integrating the Finite Element Method,Discretized Virtual Internal Bonds,and Element Partition Method(FEM-DVIB-EPM),is proposed and validated through a case study.The results demonstrate that the FEM-DVIB-EPM coupling algorithm reduces complexity and enhances solving efficiency.The length of the hydraulic fracture increases with the quantity and displacement of PFFS,and excessive displacement may result in uncontrolled fracture height.Within the parameters considered,a minimal differ-ence in fracture length is observed when the PFFS amount exceeds 130 m3,that means the fracture length tends to stabilize.This study contributes to understanding the hydraulic fracture propagation mechanism induced by SPFT,offering insights for optimizing hydraulic fracturing technology and treatment parameters.
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    Unsupervised anomaly detection in shearers via autoencoder networks and multi-scale correlation matrix reconstruction

    Yang SongWeidong WangYuxin WuYuhan Fan...
    54-64页
    查看更多>>摘要：As the main equipment of coal mining production,the anomaly detection of shearer is important to ensure production efficiency and coal mine safety.One key challenge lies in the limited or even absence of labeled monitoring data for the equipment,coupled with the high costs associated with manual annotation.Another challenge stems from the complex structure of the mining machines,making it difficult to reflect the overall operational state through local anomaly detec-tion.Consequently,the application of decoupled local anomaly detection for mining machines in practical production remains challenging.This paper presents an unsupervised learning-based method for detecting anomalies in shearer.The method includes a module for constructing a Multi-scale Correlation Matrix(MSCM)of mining machine operating condi-tions,as well as the CNN-ConvLSTM Autoencoder(C-CLA)network.The module for constructing an MSCM enhances the representation of interrelationships between various features of the equipment from different perspectives using mul-tiple correlation analysis methods.The C-CLA network integrates convolutional and convolutional recurrent neural net-works,with the convolutional structure extracting local spatial features and the ConvLSTM structure further capturing information from different time scales and feature scales,thereby enhancing the model's perceptual capabilities towards changes in equipment status.Finally,shearer anomaly detection is achieved through the analysis of reconstructed residual matrices.The rationality and practicality of the proposed method have been validated on our dataset,and the model's generalization capability has been verified through repeated experiments in similar scenarios.However,due to variations in the working environment of different mining faces and differences in equipment models,implementing detection on other mining faces often requires retraining the model with new data.Furthermore,we compared our method with other anomaly detection techniques,and our detection efficiency was superior by approximately 3％.This method effectively detects anomalies in the shearer.
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    Mechanism and prevention of coal bursts in gob-side roadway floor under thick and hard roof in the deep mining area of Ordos

    Jinlong ZhouJunfeng PanYongxue XiaTaotao Du...
    65-85页
    查看更多>>摘要：The complex stress environment in deep roadways,often exacerbated by thick and hard strata,frequently precipitates coal bursts,posing significant safety hazards.This paper investigates the mechanisms and preventive methods for coal bursts in the gob-side roadway floor(GSRF)under thick and hard roof in the Ordos region,China.First,the stress-distributing characters of GSRF were analyzed then a stress calculation formula was derived.A mechanical model was developed to determine the critical stress for buckling failure of the roadway floor strata.Criteria for the bursting instability of GSRF were then established.The lateral static load from the adjacent gob,the advancing static load from the working face,and the disturbance load from overlying thick and hard roof fractures combine to transmit high loads and energy to the road-way floor via the"roof → rib → floor"pathway,causing increased stress concentration and energy accumulation.When the conditions satisfy the criteria for bursting instability,coal bursts can occur on the roadway floor.To mitigate dynamic load disturbances,the paper proposes roof regional fracturing and abrasive water jet axial roof cutting.Hydraulic reaming of gutters in the roadway ribs and deep hole blasting at the roadway bottom corners are offered to alleviate the static loads on the surrounding rock.The implementation of targeted prevention measures for dynamic and static loads effectively reduces coal bursts in GSRF.These findings offer an example of preventing and controlling coal bursts in other mines of the Ordos region with comparable geological conditions.
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    Distribution of trace elements and rare earth elements in coal from the Bhalukasba Surni coal block,Rajmahal coalfield,Eastern India

    Saswati ChakladarSneha KumariAlok KumarAshok Mohanty...
    86-100页
    查看更多>>摘要：Exploration of secondary resources for isolation of valuable constituents,such as rare earth elements(REEs)and trace elements(TEs),is of importance owing to the need to identify new domestic sources and reduce reliance on imports.The present study systematically discusses the distribution of REEs and TEs in core samples from the coal block of Bhalu-kasba Surni {(B 1(125 m)-B9(409 m)} located in Rajmahal coalfield,Jharkhand,India,which has not been investigated previously for its geochemistry.The studied coal samples were found to be enriched in TEs whose abundances were in the order of Mn＞Mo＞Zr＞Ni＞Cr＞V＞Cu＞Zn＞Pb,and REEs(La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Er,Tm,Yb,Lu)along with Sc and Y.The average concentration of REEs with yttrium(∑REY)on an ash basis was 528 ppm,which is significantly higher than the world average for coal ash(435 ppm).Of the samples investigated,B3(182-184 m)and B8(396-399 m)demonstrated relatively higher concentrations of potentially economic elements,with B3 containing a higher proportion of middle to heavy REEs Gd,Dy,Ho and Er,and B8 showing relative enrichment in Nd and Y.On dry whole coal basis,B6(275-278 m)showed a considerably higher concentration of Ge(55 ppm)than other samples,whereas the concentration of Zr varied in the range of 90-160 ppm in the whole coal block.X-ray diffraction studies revealed the presence of quartz,keatite,hematite,zircon,anatase and orthoclase in the coal ash samples prepared at 815 ℃.REEs exhibited prominent positive correlation with Al2O3(0.4＜r＞0.9)which is supportive of their residence in primary clay minerals such as kaolinite and illite-smectite.Additionally,a positive correlation of REEs with P2O5(0.4＜r＞0.9)suggests their association with phosphate minerals(such as monazite,xenotime,apatite).Positive correlation with TiO2(r＞0.7)corroborates the possible association of REEs with anatase.The morphology of the coal ash samples viewed in SEM showed the presence of Al2O3 and SiO2 enriched irregular-sponge particles likely derived from partly-fused clay minerals,which accounted for the lower extent of REE encapsulation.The Bhalukasba Surni coal block is potentially of economic importance due to its enrichment in Ge,Zr,and the REEs.
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    Study on the flow field of multi-phase coupling slag discharge and the influencing factors of slag discharge effect in gas lift reverse circulation of drilling shaft sinking

    Longhui GuoHua ChengZhishu YaoChuanxin Rong...
    101-120页
    查看更多>>摘要：Combined with the advanced drilling of the central return air shaft in Kekegai Coal Mine,the distribution law of slag dis-charge flow field by drilling method and the influencing factors of slag discharge effect are studied.Firstly,the numerical model of gas-liquid-solid coupling slag discharge is established by CFD-DEM(computational fluid dynamics coupled dis-crete element method).Then,the flow field distribution law of the site slag outlet layout model and the optimization model is compared and analyzed.Finally,the influence of drilling parameters on slag discharge effect is studied.The results show that the best arrangement of slag suction ports is:the number is two,the length-diameter ratio is 0.4,the area ratio is 1,and the total area ratio is 1.94％.The fluid movement at the bottom of the well is mainly tangential flow,while the fluid in the slag discharge pipe is mainly axial flow.The construction parameters of efficient slag discharge are put forward:bit rotation speed is 8.7 r/min,gas injection rate is 4200 m3/h,air duct sinking ratio is 0.84,and mud viscosity is 165 MPa·s.The research results can provide useful theoretical reference for large-scale sinking construction in deep wells.
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    A novel method combining strata movement and UAV infrared remote sensing technology to evaluate mining ground damage

    Yixin ZhaoKangning ZhangChunwei LingJihong Guo...
    121-138页
    查看更多>>摘要：Mining-induced ground fissures are common problems associated with mining damage in shallowly buried coal seams in the western mining area of China.To evaluate the surface mining damage of the 12203 working face of the Huojitu Col-liery in Shendong mining area,low-altitude infrared aerial surveys were conducted on the ground at the static fissure area(O-A1)and the dynamic fissure area(O-A2)of the working face.The temperature evolution patterns of fissures,sand and plants in the infrared images were analysed.The relationship between overburden fractures and surface fissure temperature was revealed,and the influence range and temperature self-healing period of the surface affected by underground mining were determined.The results indicated that underground mining could lead to a decrease in the ground temperature above the working face.The surface temperature evolution can be divided into three zones:a temperature stabilization zone before mining,a temperature cooling zone during mining,and a temperature recovery zone after mining.The temperature of sand and plants above the working face exhibited quadratic curve changes in O-Al and O-A2,respectively.The length of the temperature reduction zone affected by mining is 40 m in O-A2,and 46.8 m in O-Al.The temperature recovery periods of ground fissures in O-Al and O-A2 were 4.0 and 4.6 d,respectively.These findings could provide a basis for evaluating mining ground damage.
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    Mechanical behaviour and acoustic emission characteristics of the reinforced soft muddy rock under various moisture content levels

    Haoyu RongWei WangGuichen LiGuangming Zhao...
    139-157页
    查看更多>>摘要：In order to investigate the failure mechanism of the reinforced muddy soft rock under the influence of the hydration reac-tion when ground water is present,a series of confined compressive tests and Acoustic Emission(AE)recordings were conducted subject to various moisture content levels and lateral confining stresses.It was found that the failure modes of the reinforced rock specimen were affected by the moisture content level and the lateral stress σ2 in a way that the load bearing capacity of the reinforced rock would increase with the lateral stress σ2 but decrease as the moisture content increased.An increase in the moisture content would reduce the extent of the influence of the lateral stress on the load bearing capacity of the reinforced rock.In addition,much less AE counts were recorded when the moisture content increased indicating that the crack initiation and propagation in this case was easier due to the reduction of the required external input energy.With increasing moisture content,the failure mode of the specimen gradually changes from sudden and brittle to progressive and ductile.Moreover,the hydration reaction became more significant leading to a complete debonding between the grout and the rock.Consequently,the reinforcement provided by the rock bolt to the rock became negligible.
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    Aqueous oxidation of coal-associated pyrite and standard pyrite mineral towards understanding the depyritization kinetics and acid formations

    Angana MahantaBinud AttryBinoy K.Saikia
    158-172页
    查看更多>>摘要：In coal mining areas,the ambient atmospheric and aqueous oxidation of pyrite minerals(FeS2)associated with coal as well as the other accompanying strata is significant in understanding the extent of acid mine drainage(AMD),the cause of severe environmental pollution.Therefore,in this paper,the oxidation kinetics of the coal-associated pyrite(CAPy)present in a coal sample(TpHM1)has been studied via aqueous leaching depyritization experiments at variety of temperatures and time intervals without the incorporation of any oxidizer.The outcomes obtained are juxtaposed with the standard pyrite mineral(SPM)oxidation at the same experimental conditions.Also,the coal and SPM slurry residues and filtrates obtained after aqueous leaching at 25 ℃ and 90 ℃ for 0 h and 24 h,respectively,were extensively analyzed through high-resolution transmission electron microscopy(HR-TEM),Powder X-ray diffraction(P-XRD),and X-ray-photoelectron spectroscopy(XPS)for evaluation of the mineralogical composition and proportions of iron and sulfur components during progression of the oxidation reaction.Both the reactions obey pseudo first-order kinetics during pyrite(FeS2)oxidation but a significant difference in the experimentally found activation energies(Ea)and rate constants(k)values of oxidation kinetics of both CAPy and SPM may be attributed to the varied geochemical compositions of the coal associated pyrite(CAPy).The rate constant for CAPy is much greater than that of SPM implying a higher Ea around 10.838 kJ/mol for SPM as compared to 1.941 kJ/mol for CAPy.The CAPy in coal(TpHM1)is more susceptible to atmospheric oxidation than that of SPM,lead-ing to the formation of acid mine drainage with lower pH.In this paper,the pH values on the basis of stoichiometric pyrite oxidation reaction were calculated and compared with the pH values obtained after aqueous leaching of CAPy to interpret the extent of acid formation and pyrite dissolution.Hence,with the assistance of the current study,further studies on the effects of mineral impurities,whereabouts of pyrite minerals in coal seams,the significance of compositional differences in the CAPy,the effect of metal oxides,and the role of alkalinity producing neutralizing agents of coal in the oxidative dis-solution process of pyrite can be investigated.
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