Current Issue

  • Research progress and key breakthroughs of practical mine pressure control theory

    SONG Zhenqi;HAO Jian;JIANG Yujing;LI Enlai;BIAN Hua;State Key Laboratory of Disaster Prevention and Ecology Protection in Open-Pit Coal Mines, Shandong University of Science and Technology;Shandong Key Laboratory of Intelligent Prevention and Control of Dynamic Disasters in Deep Mines , Shandong University of Science and Technology;

    Major disasters associated with strata movement constitute a predominant share of coal mine accidents.Establishing and perfecting mine pressure control theory is fundamental to controlling these related disasters.Based on a review of the development history of mine pressure theory, this paper summarized and refined the connotation of the 'practical mine pressure control theory' centered on overlying strata movement. Key breakthroughs in this theory were examined from three aspects, i.e., theory, technology, and equipment. In terms of theory: A dynamic structural mechanics model of the stope which reveals the evolving patterns of overlying strata movement and abutment pressure distribution was constructed, and the dynamic development characteristics of the model under different mining conditions were determined. The 'two stress fields theory' was established, and the conditions for the formation of an internal stress field were clarified. In addition, a mechanical model for working face roof control, with the position equation as its core, was built, establishing the relationship between roof control(load on supports) and the position of the rock beam. In terms of equipment:Equipment such as a three-dimensional similar material simulation test platform and a mine pressure mechanical simulation test platform were developed, which enabled the back-analysis simulation of strata movement laws and abutment pressure distribution. Monitoring instruments like large-range(200–300 mm), high-precision(0.01 mm)roof dynamic monitors were developed, forming a complete set of monitoring equipment and a platform for dynamic strata behavior. Besides, a simulation system for overlying strata movement was established. This system visualizes the mechanical models through computer simulation and facilitates mine pressure simulation and decision-making. In terms of technology: The dynamic observation technology for underground strata was proposed, enabling the prediction of main roof weighting. Meanwhile, the technology of gob-side entry driving with narrow coal pillars was developed. By positioning extraction roadways within the stable internal stress field,this technology successfully controls dynamic disasters such as rock bursts and gas outbursts induced by traditional roadways protected by large coal pillars. Finally, the philosophical essence of the 'practical mine pressure control theory' was distilled, characterized by strategic foresight, functionality orientation, practical effectiveness, and risk aversion. Five key frontier directions for future breakthroughs were identified: extreme mining conditions, controlled strata movement, regulated mining-induced stress, utilization of mine pressure, and non-intrusive control.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 7157K]

  • Strata control technology using hydraulic fracturing in underground coal mines and applications

    KANG Hongpu;FENG Yanjun;ZHAO Kaikai;CCTEG Coal Mining Research Institute;State Key Laboratory of Intelligent Coal Mining and Strata Control;Tiandi Science and Technology Co.,Ltd.;

    As coal mining progresses to greater depths and higher intensities, challenges in strata control have become increasingly prominent. Disasters such as strong ground pressure at working faces, large deformation of roadway surrounding rock, rock burst, and mining-induced seismicity are becoming more severe. Hydraulic fracturing technology, by creating artificial fractures within rock strata to proactively modify the strata structure and adjust the surrounding rock stress field, achieves the goals of weakening strata and pressure relief. It demonstrates significant potential and broad prospects in addressing strata control challenges. This paper reviewed the development history of hydraulic fracturing for strata control in coal mines. It summarized research findings on fracture propagation by means of theoretical analysis, laboratory experiments, and numerical simulations, detailing the morphology, characteristics, patterns, and main influencing factors of hydraulic fracture propagation. The technology was categorized into three types, i.e., underground fracturing, surface fracturing, and coordinated surface-underground fracturing, and their features, advantages, and applicable conditions were comparatively analyzed. Besides, the paper introduced underground local and regional hydraulic fracturing technologies, surface fracturing processes, and complete equipment systems, including characteristics and key technical parameters of fracturing pump assemblies, tool strings, slotting(notching) and perforation devices, and monitoring systems. It also discussed the mechanisms of hydraulic fracturing in roadway pressure relief, working face strata control, and rock burst prevention, revealing its core mechanical principle of "strata structure modification–strata energy release–surrounding rock stress manipulation". Furthermore, it presented typical engineering application cases, and showcased remarkable outcomes in projects such as pressure relief in kilometerdeep soft rock roadways, control of intense ground pressure in 10 m super-high mining faces, and prevention of rock burst and mining-induced seismicity. Finally, the paper analyzed existing problems with current hydraulic fracturing practices and prospects future development directions. To be specific, the fracturing concept should evolve towards being proactive, regionalized, and integrated; the fracturing design should move towards quantification, visualization, and dynamization; the fracturing processes and equipment should advance towards precision, automation, and intelligence; and the fracturing monitoring should develop towards multi-source integration, accuracy, and real-time capability. The ultimate goal is to establish a comprehensive hydraulic fracturing strata control technology system characterized by "precise detection–quantitative design–intelligent operation–real-time monitoring–comprehensive evaluation–dynamic feedback", providing crucial technical support for safe and efficient coal mining.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 6433K]

  • Review and prospects of classification methods for rockburst intensity

    GONG Fengqiang;LEI Yan;DAI Jinhao;School of Geology Engineering and Surveying, Chang'an University;School of Civil Engineering, Southeast University;School of Civil and Architectural Engineering, East China Jiaotong University;

    As underground engineering projects such as mining, transportation, and hydropower continuously advance deeper into the earth, the frequency and intensity of rockburst disasters encountered during deep construction have significantly increased. Accurate prediction of rockburst intensity is becoming increasingly crucial for the prevention and control of rockburst disasters. This study reviews 23 domestic and international classification methods for rockburst intensity, and systematically compares the characteristics of 8 qualitative and 7 quantitative indicators used in these methods. Qualitative indicators often focus on the indentification of macroscopic features, such as acoustic features, kinetic behavior, temporal characteristics, and engineering impacts, which are susceptible to subjective experience. In contrast, quantitative indicators, such as strength-stress ratio and rockburst pit depth, seek to establish mapping relationships between measured data and rockburst intensity, though their scientific rigor requires further investigation. This study also introduces recent advances in coupled strength-stress criteria and computational methods for rockburst pit depth, which contributes more scientifically grounded quantitative indicators for rockburst intensity classification. Based on the review, the study envisions future trends in classification methods for rockburst intensity, including AI-driven intelligent and unmanned measurement technologies for quantitative indicators of rockburst, as well as automated quantitative analysis technologies for qualitative indicators of rockburst. These methods aim to reduce errors and safety issues arising from manual data collection. Additionally, the study suggests constructing a scientific and comprehensive rockburst database based on collected data and developing a multi-indicator rockburst intensity integrated classification model. Furthermore, it proposes to create an intelligent classification platform based on this model to achieve full-process automation in rockburst hazard assessment. Finally, given the frequent occurrence of rockburst disasters at the arch floor and tunnel face in deep construction, the study calls for exploring ways to classify rockburst intensity at these locations and for estimating rockburst pit depth.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3048K]

  • Preliminary investigation on neutron emission characteristics during the failure process of coal and rock under uniaxial compression

    ZHAO Yixin;JING Gang;LIU Bin;GIUSEPPE Lacidogna;School of Energy and Mining Engineering,China University of Mining and Technology-Beijing;Xinjiang Key Laboratory of Coal-bearing Resources Exploration and Exploitation,Xinjiang Institute of Engineering;State Key Laboratory of Digital Intelligent Technology for Unmanned Coal Mining,Anhui University of Science and Technology;Department of Structural,Geotechnical and Building Engineering,Politecnico di Torino;

    Neutron emission(NE) has the advantage of electromagnetic interference immunity. To explore a new monitoring method for potential application on the forecast of dynamic hazards in mining, the NE characteristics of coal, granite, and magnetite samples were investigated by performing uniaxial compression experiments.Acoustic emission(AE) signals were synchronously monitored in the experimental process. The early warning indicators of coal and rock were discussed based on the acquired NE and AE data. It was found that the NE signals vary enormously during the failure process, which demonstrates its potential to serve as a novel method for monitoring coal and rock instability. Samples with higher iron contents are more prone to induce NE upon sudden failure, and the amplitude of NE is correlated with the iron content. For the strongly burst-prone coal sample from Hongqinghe Coal Mine, the peak NE intensity at instability is approximately 13.3 times the background NE intensity of the test environment. In contrast, for the weakly burst-prone coal sample from Wanglou Coal Mine, it shows no noticeable difference from the background intensity throughout failure. AE can continuously characterize the entire process of damage accumulation, while NE displays a sharp surge at the critical point of macroscopic instability. The two kinds of signals are complementary in terms of time sequence and physical mechanisms. Prior to instability, NE is characterized by the nonlinear growth of cumulative values and an order-of-magnitude jump in the coefficient of variation. When the samples approach instability, all coefficients of variation curves exhibit a significant sudden surge to the peak value.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 2941K]

  • Deformation and failure characteristics of rock-coal-rock combinations with different coal thickness ratios under constant amplitude cyclic loading and unloading

    LIN Haifei;CHEN Zhiheng;ZHOU Bin;LIU Sibo;SHUANG Haiqing;JI Pengfei;ZHAO Pengxiang;College of Safety Science and Engineering, Xi'an University of Science and Technology;Western Coal Mine Gas Disaster Prevention and Control Key Laboratory of Colleges and Universities in Shaanxi Province;Western Engineering Research Center of Mine Gas Intelligent Drainage for Coal Industry;

    In response to the multiple disturbance effects of periodic weighting on the "roof-coal-floor" composite structure during the working face mining process, uniaxial conventional loading and constant amplitude cyclic loading-unloading tests were conducted on rock-coal-rock combinations. The deformation and failure characteristics of the combinations were analyzed using digital speckle correlation method(XTDIC), revealing the failure mechanisms of combinations with varying coal thickness ratios under constant amplitude cyclic loading-unloading paths. Research shows that: under the constant amplitude cyclic loading and unloading path,the peak compressive strength of the combination is negatively correlated with the proportion of coal thickness.Compared with the conventional uniaxial loading, the proportion of coal thickness is from low to high, and the compressive strength is reduced by 13.98%, 22.34%, 11.82% and 6.36% from 16.10 MPa, respectively, which are between the strength of single rock and single coal; With the increase of the proportion of coal thickness in the combination, the peak value of elastic modulus in the loading stage decreased from 2.13 GPa to 1.69 GPa, 1.31 GPa and 0.87 GPa, except for the first loading, the unloading elastic modulus is always lower than the loading elastic modulus; When the coal rock ratio is 1∶0.86∶1 and 1∶1.33∶1, the maximum principal strain field concentration area of the combination is dispersed and shows a multi regional development trend, and the overall failure is a tensile shear composite failure. When the coal rock ratio increases to 1∶2∶1 and 1∶3∶1, the strain concentration area develops to a directional strip, showing an overall shear failure; With the loading and unloading of axial stress, the overall displacement of each part of the combination shows the phenomenon that the elastic displacement in the initial compaction stage increases to the rebound fluctuation of the cyclic elasticplastic displacement and finally increases sharply before the peak failure, while the lateral displacement shows the phenomenon that the lateral compression expansion in the initial compaction stage reaches the cyclic loading response, the residual expansion in the unloading stage reaches the sharp expansion before the failure and finally stabilizes; The fracture opening presents the characteristics of "ladder wave" transition growth and evolution, and shows strong nonlinear acceleration when it is close to the peak strength threshold.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3939K]

  • Influence of water immersion depth on mechanical damage behavior of coal and rock and multi-scale instability mechanism

    CHEN Guangbo;ZHENG Shaohuang;ZHANG Junwen;LI Tan;WANG Eryu;WANG Chuangye;LIU Yejiao;CAO Jian;ZHANG Guohua;TANG Wei;GAO Ning;School of Mining and Coal, Inner Mongolia University of Science and Technology;School of Energy and Mining Engineering,Shandong University of Science and Technology;School of Energy and Mining, China University of Mining and Technology-Beijing;Heilongjiang University of Science and Technology;

    In water-rich mines or under water-rich mining conditions, the mechanical properties of coal-rock masses deteriorate significantly under environments with different water immersion depths, which jeopardizes the safety and stability of coal and rock system. In order to investigate the mechanical properties and damage characteristics of coal and rock under different immersion depths, typical coal, sandstone and shale were taken as research objects, and axial compression and acoustic emission tests were carried out at six different immersion depths of 0, 20, 40, 60, 80, and 100 mm to analyze their mechanical damage and instability mechanisms. The results show that:(1) With the increase of immersion depth, the elastic modulus, damage stress and compressive strength of coal rock decrease gradually, and the deterioration degree of elastic modulus and compressive strength of coal rock increases significantly, and the deterioration effect is the largest in the stage of 0-20 mm immersion.(2) With the increase of immersion depth, the cumulative ringing count and peak ringing count of acoustic emission decreased gradually. The cumulative energy is gradually reduced by the depth of immersion.(3) Based on acoustic emission RA-AF, Tensile cracks and shear cracks coexist in sandstone samples with different immersion depths. With the increase of immersion depth, the proportion of tensile cracks increases gradually, and the proportion of shear cracks decreases gradually.(4) Based on acoustic emission, the damage evolution model of coal rock is constructed, and the rationality of the damage model is verified from three aspects: stress-strain curve, damage effect and compressive strength. The damage evolution process of coal rock can be divided into the initial stage of damage, the stage of damage development and the stage of damage acceleration. With the increase of immersion depth, the damage variable of coal rock increases.(5) The multi-scale instability and failure mechanism of soaked coal rock is clarified from the "micro-meso-macro perspective". Under the action of soaking, the mineral particles inside the coal rock are dissolved, and the volume of the mineral particles decreases.Under the action of load, the mineral particles undergo micro-fracture, large-scale fracture, and full-fracture. New cracks are generated inside the coal rock and expand and penetrate. Cracks appear macroscopically, and the coal rock is unstable and destroyed. This research can provide useful reference for the safety, stability, prevention and evaluation of project coal and rock mass under the influence of immersion depth.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 5677K]

  • Study on spectral response characteristics of artificial acoustic signals of gas-bearing coal under mechanical vibration

    DU Feng;CUI Weilong;MA Ji;WANG Kai;WEI Fengqing;SUN Jiazhi;Key Laboratory for Precise Mining of Intergrown Energy and Resources,China University of Mining and Technology-Beijing;School of Emergency Management and Safety Engineering,China University of Mining and Technology-Beijing;College of Safety Science and Engineering,Henan Polytechnic University;

    With the deepening of coal mining depth, external vibrations from various underground operations lead to frequent outburst accidents and cause serious damage. By analyzing the amplitude-frequency characteristics of artificial acoustic signals under different gas pressure conditions, it is possible to analyze the stress-strain state of coal and rock near the working face, reflect the strength state of the coal body, and predict the risk of dynamic phenomena in the working face. In this study, a test device for artificial acoustic signals of gas-bearing coal under mechanical vibration excitation was independently designed and developed. On this basis, the experimental study on the spectral response characteristics of artificial acoustic signals of gas-bearing coal under mechanical vibration excitation was carried out. Furthermore, the fluid-solid coupling model of gas-bearing coal considering the spectral response characteristics of artificial acoustic signals was derived, and the mechanical field characteristics of gas-bearing coal were obtained based on numerical simulation. The main conclusions are as follows:(1) The values of the spectral response characteristic index K of artificial acoustic signals of both gasbearing and non-gas-bearing coal bodies increase first, then decrease, and ultimately increase again with the rise of axial loading stress, and the relationship between the K value and the axial loading stress can be expressed in the form of an exponential function, where the gas pressure influences the constant term. Besides, the K value also declines with the rise of gas pressure.(2) The coal stress and the K value change obviously in the stress relief and stress concentration areas, but they are relatively stable in the original rock stress area. The relationship between the K value and the coal stress can be fitted by an exponential function, where a higher gas pressure corresponds to a greater constant term C value. The variation trend of the K value is consistent with the distribution law and variation trend of the coal stress, which is a mark of its ability to reflect the stress state of coal. Affected by factors such as coal stress and gas pressure, the permeability and the K value show specific variation patterns.This study perfects the theory of using artificial acoustic signals excited by mechanical vibration to reflect the coal stress state and predict the gas outburst risk and provides innovative technical means and methods for prevention and early warning of coal and gas outburst, which is of great significance for ensuring safe production in coal mines.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3127K]

  • Correlation between cutting parameters of roadheader-bolters and tensile anisotropy of coal

    YANG Sen;XU Jiawei;GUO Yubo;HAN Jiangwei;MA Junqiang;College of Energy and Mining Engineering, Xi'an University of Science and Technology;Key Laboratory of Western Mine Exploitation and Hazard Prevention Ministry of Education;

    Integrated excavation and bolting construction represents the developmental direction for intelligent and efficient tunneling in coal seam roadways. Drum cutting parameters serve as first-hand data for perceiving changes in coal mass properties, and understanding their correlation with the mechanical properties of coal is the theoretical foundation for achieving intelligent perception during tunneling. Tensile anisotropy, a typical mechanical characteristic of coal, significantly impacts rock breaking and support design. With the aid of the particle discrete element method, tensile anisotropy in coal models was achieved through an "equivalent interlayer" structure. Meanwhile, controllable adjustment of coal tensile anisotropy along the drum cutting direction was realized by coupling the drum and coal models. On this basis, five sets of dynamic cutting experiments were performed to analyze the variation characteristics of drum torque and cutting resistance signals during the cutting process and ultimately reveal the influence of coal tensile anisotropy on cutting parameters of roadheaders-bolters. The following beneficial conclusions were drawn. As the angle between the downward cutting direction of the drum and the loading direction of the minimum tensile strength narrows, drum torque increases while torque fluctuation is gradually suppressed, with the amplitude decreasing from 6,209 N·m to 5,491 N·m. The cutting resistance signals reflect a seesaw relationship between coal "compaction" and drum deceleration phenomena, and coal exhibits three distinct stages: "overall disturbance → disturbance dissipation →localized failure". Higher alignment between the downward cutting direction of the drum and the loading direction of the minimum tensile strength results in stronger vibration response of coal to cutting and more intense localized failure effects.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 2526K]

  • Influence of bi-modulus property of rock on tensile strength evaluation in the Brazilian test and its calculation improvement

    WEI Jiong;CCTEG Coal Mining Research Institute;State Key Laboratory of Intelligent Coal Mining and Strata Control;

    Rock materials commonly exhibit tension-compression bi-modulus behavior, which has a crucial influence on the determination of tensile strength in the Brazilian test but is often neglected in traditional analyses.To systematically investigate the effects of this property on the elastic modulus and stress distribution in Brazilian discs, a stress-driven bi-modulus numerical model is developed. The mechanical behavior of the Brazilian disc under different compression-to-tension modulus ratios is studied, and the calculation differences between the transversely isotropic model and the bi-modulus model are compared. The influence of tension-compression bimodulus characteristics on tensile strength is analyzed, and a new calculation formula is proposed. The results indicate that:(1) Tension-compression bi-modulus characteristics significantly affect the elastic modulus and stress distribution in the Brazilian disc, especially under high compression-to-tension modulus ratios;(2) The stress and strain calculation results in the vertical direction are consistent between the transversely isotropic model and bi-modulus model, but there are significant differences in the horizontal direction;(3) The traditional tensile strength calculation formula based on isotropic assumptions overestimates rock strength, with the relative error increasing as the compression-to-tension modulus ratio increases, reaching up to 54.95%;(4) The proposed formula accurately describes the horizontal stress at the disc center, with relative errors below 5%. It effectively mitigates strength estimation errors caused by neglecting the difference between tensile and compressive moduli,thereby providing a reliable method for determining the tensile strength of bi-modulus rocks.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 1795K]

  • Dynamic coupling relationship of surrounding rock-support and intelligent control strategy for deep and complex working faces

    REN Huaiwei;GONG Shixin;LIU Kai;HAN Zhe;ZHANG Shuai;CCTEG Coal Mining Research Institute;Coal Mining and Designing Branch,China Coal Research Institute;

    Deep coal seams in complex geological environments are characterized by extremely high in-situ stress, severe surrounding rock deformation, and considerable variations in both strike and dip angles. These factors cause pronounced spatial heterogeneity in surrounding rock stress distribution and structural morphology,resulting in highly variable and dynamically evolving support system requirements. Existing support systems,constrained by fixed design parameters and limited functional adaptability, are incapable of meeting the requirements of intelligent mining in such coal seams. In this study, taking a kilometer-deep ultra-long working face in a demonstration mine of the Huainan mining area as the research object, a comprehensive analytical framework for the force coupling(magnitude, direction, and point of application) and spatial configurationdisplacement coupling between the surrounding rock and the support system was established to reveal the spatiotemporal evolution mechanisms of overburden zonal fracturing and dynamic stress redistribution in ultralong working faces. On this basis, a deep-learning neural network-based coupled prediction model was developed to achieve intelligent forecasting and real-time assessment of the stress states and positional behavior of both the surrounding rock and the support system. Furthermore, based on a non-parametric clustering algorithm, the working face was divided into distinct zones according to variations in support resistance and spatial position, and corresponding support and position control strategies were proposed for each zone. Subsequently, an integrated intelligent analysis and regulation system, termed "Three Measurements, Two Controls, and One Platform", was constructed for working faces in complex geological environments. This system enables comprehensive perception of surrounding rock mechanical behavior, support system stress responses, and spatial configurations,as well as integrated decision-making and control, significantly enhancing the ability of the support system to adapt to both gradual geological evolution and abrupt dynamic disturbances. Field application results verify its effectiveness in improving the adaptability and flexibility of the support system under complex conditions. In the ultra-long working face configuration, with a mining height of 5.0–6.2 m, an average dip angle of 14°, and a maximum strike angle of 17°, the cutting cycle frequency was increased to five passes per day, representing a38.29% improvement compared with conventional mining methods. During a three-month demonstration period,the working face advanced 210.2 m and produced nearly 600 000 tons of coal. The system realizes safe and highly efficient mining of deep "three-soft" coal seams with a large mining height in the Huainan mining area.The intelligent mining approach adapted to the characteristics of deep and complex coal seams proposed in this study is expected to provide technical support for the safe and efficient exploitation of deep coal resources.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3145K]

  • Basic principle and engineering of dynamic disaster prevention and control in deep strata

    TAN Yunliang;YANG Shenglong;LIU Xuesheng;FAN Deyuan;LI Xuebin;WANG Yu;College of Energy and Mining Engineering, Shandong University of Science and Technology;State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology;

    Deep coal mining has become inevitable. Research on the occurrence mechanism, prevention and control principle, and engineering technology of dynamic disasters in deep strata is of great significance for ensuring coal mine safety and practicing national requirements for stabilizing coal supply. Firstly, the dynamic disaster processes induced by overburden movement under three typical conditions, namely overburden in the working face advance direction, lateral overburden on the gob side, and overburden through fault cutting, were discussed. The corresponding mechanical models of overburden structure were established, and the mechanical mechanisms of roadway dynamic impact induced by overburden movement was solved. Then, based on the complexity of deep strata structure and the diversity of disaster-inducing characteristics, the full-scale control method for strata spatial structure was proposed. The mechanical principle of full-scale pressure relief, from local pressure relief of roadway surrounding rock to regional strata modification, was revealed. Finally, the basic principles of disaster prevention and control with the main contents of overburden structure modification, upward pressure relief mining, coal seam weakening, coal pillar width design, and high prestressed support were clarified,and many prevention and control engineering practices were carried out. The results show that the surrounding rock deformation in Maiduoshan Coal Mine decreases by 44.61%–46.53% after hydraulic fracturing; the coal displacement in Zaoquan Coal Mine drops by 68.24%–77.78% after large-diameter borehole pressure relief; and the rib deformation in Daanshan Coal Mine falls by 62.5% after high-strength energy absorption support. Upward pressure relief mining and a multi-parameter intelligent monitoring and early warning platform have been successfully applied in Xinzhouyao Coal Mine and Xinjulong Coal Mine, respectively.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3344K]

  • Research and application on digitalization and visualization of stress evolution characteristics in coal mining stopes

    WANG Hongwei;WANG Zeliang;ZHU Zhanbin;ZHU Jie;ZENG Xiantao;JIANG Yaodong;School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing;Mataihao Coal Mine,Inner Mongolia Ordos Yongmei Mining Industry Co.,Ltd.;JCHX Mining Management Co.,Ltd.;

    Studying the spatio-temporal distribution law and evolution characteristics of stress in coal mining stopes is the key to establishing disaster early warning indicators and implementing effective prevention and control. Building upon the recent research progress of our research team in digital modeling and intelligent mining of coal mines, this research focuses on constructing a stope stress database and achieving the visual output of its evolution characteristics. To be specific, a digital reconstruction method for stope stress through data acquisition, fidelity preservation, transmission, and normalization processing was proposed based on the multisource data of stope stress, and a multi-source data fusion and efficient storage database equipped with functions such as intelligent database retrieval, information output, and cloud platform query was constructed. Aiming at the problems such as data discreteness in the stope stress database, a data interpolation method based on microelement piecewise Fourier transform was introduced, and a three-dimensional interpolation algorithm of "generating lines from points, generating surfaces from lines, and generating volumes from surfaces" was put forward, achieving the continuity representation of multi-source discrete data. Meanwhile, three types of stope stress inversion models, namely linear, polynomial, and exponential, were constructed based on key points and key regions, and a three-dimensional visualization output inversion algorithm for the stope stress evolution characteristics was developed. Furthermore, physical experimental research on the stope stress evolution characteristics was conducted, through which the construction of a multi-source database of stope stress and the visualization output of its evolution characteristics were achieved at the laboratory scale. Taking the typical structure of Da'anshan Coal Mine of Beijing Haohua Energy Group and the 3105 mining face of Mataihao Coal Mine in Ordos, Inner Mongolia as the engineering geological background, the fine interpolation of the in-situ stress field and the visualization inversion of mining-induced stress based on micro-seismicity positioning and hydraulic support stress were carried out, achieving the dynamic visualization output of stope stress at the field scale. The research results show that the collection and fidelity, effective fusion, and classified storage of stope data are realized through multi-source data missing filling, repetition elimination, data noise reduction, and format conversion, and the database can conduct precise and rapid query and location of stope data based on retrieval conditions. The stope stress interpolation algorithm based on Fourier transform improves accuracy by 88%, 82%,and 74% respectively in one-dimensional, two-dimensional, and three-dimensional stress continuity representations. By acquiring and analyzing the support pressure and micro-seismicity data of the mining face, the dynamic evolution process of the mining-induced stress of the mining face was reproduced at the field scale. The distribution of multi-source monitoring data is in good agreement with the inversion results, verifying the accuracy of the inversion results.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 6629K]

  • Evolution law and fuzzy morphological discrimination of plastic zone of surrounding rock in soft rock roadway

    LIU Jiashun;WANG Siyu;ZUO Jianping;ZHENG Zhiyong;ZHANG Xin;JIA Baoxin;School of Civil Engineering, Liaoning Technical University;School of Mechanics and Civil Engineering, China University of Mining and Technology-Beijing;China Railway18 th Bureau Group Co., Ltd.;

    The stress disturbance caused by roadway excavation will cause the change in the plastic zone of surrounding rock, resulting in uneven deformation of surrounding rock, roof collapse, roof fall, and other engineering disasters. In order to study the influences of lateral pressure coefficient(λ) and principal stress direction on the plastic zone of surrounding rock, based on the butterfly plastic zone theory, the principal stress deflection angle(α) is introduced, and the boundary equation of plastic zone of surrounding rock considering the principal stress direction is constructed. The evolution law of plastic zone of surrounding rock under different lateral pressure coefficients and principal stress deflection angles is studied and verified by FLAC~(3D) numerical simulation. The results show that when different λ and α act, the plastic zone of roadway surrounding rock presents three morphological characteristics: circular(CS type), oval(OS type) and butterfly(BS type). In addition, λ affects the shape of plastic zone, while α affects the failure position of surrounding rock. Together,they affect the expansion range of plastic zone. The angle between the butterfly leaf and the vertical direction changes linearly with the variation of α. Based on the theory of fuzzy mathematics, a fuzzy evaluation method of the plastic zone morphology of soft rock is proposed. Taking the 20110 working face of Gaojialiang Coal Mine as the engineering background, the reliability of the proposed evaluation method is verified by numerical simulations and field loose circle tests. An asymmetric coupling support scheme combining 'long and short anchor(cable) +steel mesh + shotcrete + shallow grouting' is proposed, which significantly reduces the convergence deformation of surrounding rock surface. The research results can provide theoretical support for deformation control and disaster prevention of surrounding rock in underground engineering.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 2710K]

  • Study on dynamic subsidence mechanical model and time-space evolution law of key strata

    YANG Ziyi;LI Yingfu;XU Ying;YU Meilu;KONG Peng;YANG Rongzhou;LI Chunyuan;BAI Linyang;CAI Hongwei;School of Civil Engineering and Architecture, Anhui University of Science and Technology;State Key Laboratory of Digital and Intelligent Technology for Unmanned Coal Mining, Anhui University of Science & Technology;School of Mining Engineering,Anhui University of Science and Technology;Deep Mining and Rock Burst Research Institute, Chinese Institute of Coal Science;

    Reasonable lag time of gob-side entry driving is the key to alleviate the mine pressure and improve the efficiency of safe mining. Based on the thin plate theory, the Maxwell model is introduced to establish the relationship between the time parameters and the migration of the key strata. The dynamic subsidence mechanical model of roof breaking is futher validated using the numerical simulation and engineering practice. The results show that the stress concentration on the upper surface of the key stratum is the key factor of rock breaking, and the mining step distance and time are linearly related to the deflection of the roof during the compaction period.The numerical simulation results show that the displacement of the key strata in the goaf during the compaction period(within 30 days) is rapidly affected by the residual mining, and the stress in the middle of the key strata in the goaf is transmitted from the center to the edge, and finally concentrated in the roof of the roadway. After stopping mining, the stress concentration in the goaf is significant in a short time, and there is still a tendency of dynamic disasters. Roadway excavation is not recommended in a short time(within 60 days). The mine pressure monitoring and microseismic data in the field proved the residual influence of mining dynamic pressure from the perspective of time and space. The microseismic events gradually developed from the deep to the shallow, which confirmed that there was a spatial and temporal evolution process from stress concentration to balance during the compaction period of the goaf. Taking the time parameter as the connection point, and combining the key stratum movement and roadway excavation time organically have important theoretical guiding significance for the selection of gob-side entry driving time.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3679K]

  • Research on the pre-splitting technology of composite hard roof with deep-shallow hole coordinated blasting based on the thin plate theory

    ZHANG Guanghui;JIANG Junjun;China Coal Research Institute;State Key Laboratory of Coal Mine Disaster Prevention and Control;Beijing Engineering and Research Center of Mine Safety;

    The composite hard roof in the southeastern Shanxi mining area exhibits characteristics of low-level large-span suspended roof and high-level extensive delamination, which can easily induce creep deformation or impact dynamic disasters in the roadways. To improve the stope boundary morphology and promote roof rotation and subsidence, a technique for maintaining roadway integrity and mitigating impact disasters by using deepshallow hole cooperative blasting to induce mutual feedback and collapse of high-low level roofs is proposed.Research indicates that the transformation of the goaf boundary from a fixed end to a simply supported end liberates the boundary constraints of the roof. Leveraging the deep-shallow hole cooperative guidance mechanism, the role of the shaped charge tube in controlling the shaped charge flow, and the mutual feedback mechanism between high-low level roofs, the development length of blasting fractures in the axial direction of the roadway is significantly extended, creating basic conditions for the transformation of the fixed end into a simply supported end. The construction parameters for pre-splitting blasting of the roof in the cutting and extraction roadways have been determined through theoretical calculations and field engineering cases. Engineering practice shows that the blasting holes in the cut-off tunnel prompt the initial roof of the working face to change from a fourend fixed support to a three-fixed and one-simplified support. The initial pressure step distance of the working face is reduced by 28% after the pre-splitting blasting of the cut-off tunnel roof. The deep and shallow hole coordinated blasting in the 13132 roadway forms a dense fracture zone 18 to 40 meters above the coal seam,improving the boundary conditions of the roof of the transport entry and weakening the energy storage property of the roof. The energy of 88% of the microseismic events in the 13132 roadway area is reduced to 12 500 to 27 500 joules. The periodic pressure step distance and dynamic load coefficient of the 1312 working face are reduced to9.5 meters and 1.27 respectively. Both the pressure step distance and pressure intensity are decreased. This indicates that deep-shallow hole cooperative blasting pre-splitting can effectively improve the morphology of the composite hard roof at the stope boundary and play a role in maintaining roadway integrity and mitigating impact disasters during extraction work.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 2890K]

  • Research and application of the spatial evolution of overburden fractures and the law of gangue slurry interventional filling in the stope

    PAN Hao;XIE Shengrong;GU Wenzhe;SONG Tianqi;QIU Fengqi;DU Xing;School of Energy and Mining Engineering, China University of Mining and Technology-Beijing;College of Energy Science and Engineering, Xi'an University of Science and Technology;China Coal Shaanxi Yulin Energy and Chemical Co., Ltd.;

    This study is aimed at addressing the challenges in quantitatively characterizing the spatial distribution features and filling volume of overburden fractures during gangue slurry filling. To achieve this aim, the overburden migration patterns and fracture development mechanisms within the stope were systematically investigated. Besides, a quantitative computational model was developed to evaluate cavity and fracture spaces in both caved and fractured zones, and the regulatory effects of key parameters including mining height, rock fragmentation coefficient, compacted zone length of the caved zone, and working face advance length on fracture space evolution were elucidated. The results show that the volume of cavity and fracture spaces in the noncompacted zone of the caved zone is about 2.5 times that in the compacted zone and about 7.5 times that in the fractured zone. On this basis, three gangue slurry interventional filling experiments of different scales were performed, and the flow and diffusion dynamics within the caved zone were analyzed. Furthermore, a theoretical predictive model for gangue slurry interventional filling volumes applicable to both low-level grouting and adjacent grouting methods was established. Field validations demonstrate that gangue slurry exhibits excellent flow and diffusion performance in the caved zone, with model predictions showing strong agreement with actual filling volumes. The proposed framework provides reliable theoretical guidance for gangue slurry filling engineering applications.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 3789K]

  • Physical simulation of strong strata behaviors under high-position confined water

    YUAN Fang;TANG Jianxin;KONG Lingrui;YAN Zhenxiong;Vanadium and Titanium Critical Strategic Materials Key Laboratory of Sichuan Province,Panzhihua University;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University;

    This study aims to explore the mechanisms underlying the strong strata behavior in the presence of high-position confined water. To this end, a physical model incorporating a confined water testing system was developed through physical simulation to analyze the fracture and movement characteristics of high-position confined water. The experimental findings reveal that when high-position confined water is present, the strata controlling the rock pressure of the working face transitions from the first sub-key strata to the high main key strata. Besides, the initial and periodic fracture steps of the high main key strata diminish substantially, with the fracture position migrating toward the coal wall. In the strata below the aquifer(high main key strata), integrated composite fracture characteristics from top to bottom are observed, and the fracture position of the roof advances from the rear of the roof control area to the coal wall. During composite roof fracture, the fracture development height, maximum roof displacement, and strata fracture angle increase substantially by 743%, 509%, and 27%,respectively, leading to severe roof weighting. These findings shed light on the underlying causes of the strong strata behavior. Additionally, the action of high-position confined water notably expands the concentration range and magnitude of advance abutment pressure within the working face. Specifically, the average increases in the range of the front abutment pressure rise zone, the peak abutment pressure, and the range of the rear abutment pressure rise zone for the first and second sub-key strata and the high main key strata reach 611%, 33%, and 124%, respectively.

    2026 01 v.8;No.34 [Abstract][OnlineView][Download 5666K]