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Triaxial compression behavior of large-scale jointed coal: a numerical study

International Journal of Coal Science & Technology 2022年第5期9卷 81-95页

作者： Xiaoqing Wang fuqiang gao CCTEG Coal Mining Research Institute BeijingChina Mining&Designing Branch China Coal Research InstituteBeijingChina State Key Laboratory of Coal Mining and Clean Utilization(China Coal Research Institute) BeijingChina

Accurate estimation of the triaxial compression behavior of jointed coal is essential for coal *** studies addressed the triaxial compression behavior of large-scale rock mass,especially with real joint *** employed a numerical synthetic rock mass(SRM)method to study the triaxial compression behavior of jointed ***-coal specimens were constructed based on in-situ joint measurements and microparameter calibration against laboratory experiments.A series of triaxial compression tests under different loading orientations and confining pressures were numerically performed to obtain joint and confining-pressure effects on the triaxial compression behavior and reveal the failure mechanism of jointed *** suggest that the triaxial compression behavior of the jointed coal has strong joint and confining-pressure *** weaken the strength and elastic modulus,reduce the lateral deformation,and affect the geometries of the shear-rupture *** increase in the confining pressure causes the peak and residual strength increase *** an increase in the confining pressure,the elastic modulus increases sharply at low confining pressure,the mechanical behavior transitions from brittleness to ductility,the failure mode transitions from shear-rupture surface to plastic flow,and the joint effect diminishes and even *** jointed coal fails by means of a shear-rupture surface under triaxial compression loading with a confining pressure(which is not too high),and the geometries of the shear-rupture surface vary with the distribution of joints.

关键词： Jointed coal Triaxial compression Synthetic rock mass Failure mode

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Numerical analysis on the factors affecting post-peak characteristics of coal under uniaxial compression

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International Journal of Coal Science & Technology 2024年第1期11卷 42-60页

作者： Zhiguo Lu Wenjun Ju fuqiang gao Taotao Du CCTEG Coal Mining Research Institute BeijingChina State Key Laboratory of Coal Intelligent Mining and Strata Control(China Coal Research Institute) BeijingChina

The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting *** the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal *** this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading *** research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading *** response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are *** result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation *** efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.

关键词： Post-peak behavior Synthetic rock mass Coal bursts Coal burst prevention

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Effect of dynamic loading conditions on the dynamic performance of MP1 energy-absorbing rockbolts:Insight from laboratory drop test

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International Journal of Mining Science and Technology 2023年第2期33卷 215-231页

作者： Jinfu Lou fuqiang gao Jianzhong Li Guiyang Yuan Mostafa Sharifzadeh CCTEG Coal Mining Research Institute Beijing 100013China State Key Laboratory of Coal Mining and Clean Utilization Beijing 100013China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 110819China

Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.

关键词： Energy-absorbing rockbolt Dynamic performance Drop test Residual elastic energy(REE) Energy absorption rate(EAR) Dynamic capacity envelope

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Mechanical behaviors of coal measures and ground control technologies for China's deep coal mines-A review

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 37-65页

作者： Hongpu Kang fuqiang gao Gang Xu Huaiwei Ren CCTEG Coal Mining Research Institute BeijingChina Coal Mining Branch China Coal Research InstituteBeijingChina State Key Laboratory of Coal Mining and Clean Utilization China Coal Research InstituteBeijingChina

This paper reviews the major achievements in terms of mechanical behaviors of coal measures,mining stress distribution characteristics and ground control in China’s deep underground coal *** three main aspects of this review are coal measure mechanics,mining disturbance mechanics,and rock support *** studies related to these three topics are reviewed,including the geo-mechanical properties of coal measures,distribution and evolution characteristics of mining-induced stresses,evolution characteristics of mining-induced structures,and principles and technologies of ground control in both deep roadways and longwall faces.A discussion is made to explain the structural and mechanical properties of coal measures in China’s deep coal mining practices,the types and dis-tribution characteristics of in situ stresses in underground coal mines,and the distribution of mining-induced stress that forms under different geological and engineering *** theory of pre-tensioned rock bolting has been proved to be suitable for ground control of deep underground coal *** use of combined ground control technology(*** support,rock mass modification,and destressing)has been demonstrated to be an effective measure for rock control of deep *** developed hydraulic shields for 1000 m deep ultra-long working face can effectively improve the stability of surrounding rocks and mining efficiency in the longwall *** ground control challenges in deep underground coal mines in China are discussed,and further research is recommended in terms of theory and technology for ground control in deep roadways and longwall faces.

关键词： Deep underground coal mine Mechanical behavior Mining-induced stress Mining-induced fractures Ground control for roadways Ground control for working face

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Grouting theories and technologies for the reinforcement of fractured rocks surrounding deep roadways

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Deep Underground Science and Engineering 2023年第1期2卷 2-19页

作者： Hongpu Kang Wenzhou Li fuqiang gao Jianwei Yang CCTEG Coal Mining Research Institute BeijingChina Coal Mining Branch China Coal Research InstituteBeijingChina State Key Laboratory of Coal Mining and Clean Utilization(China Coal Research Institute) BeijingChina

Grouting is an effective method to improve the integrity and stability of fractured rocks that surround deep *** years of research and practice,various theories and a complete set of grouting technologies for deep roadways with fractured rocks have been developed and are widely applied in Chinese coal mining *** paper systematically summarizes and analyzes the research results concerning the theory,design,materials,processes,and equipment for the grouting and reinforcement of fractured rocks surrounding deep ***,in terms of grouting methods,pregrouting,groutingwhile-excavation,and postgrouting methods are explored;in terms of grouting theory,backfill grouting,compaction grouting,infiltration grouting,and fracture grouting theories are *** addition,this paper also studies grouting borehole arrangement,water-cement ratio,grouting pressure,grouting volume,grout diffusion radius,and other grouting parameters and their determination *** this basis,this paper explores the physical and mechanical properties of organic and organic-inorganic composite grouting materials,and assess grouting reinforcement quality testing methods and *** as the field cases,the application of pregrouting in front of heading faces,groutingwhile-excavation,and postgrouting in the Kouzidong coal mine are then introduced,and the effects of the grouting reinforcements are *** paper proposes a development direction for grouting technology based on problems existing in the grouting reinforcement of fractured rocks surrounding deep roadways.

关键词： deep roadways development direction field study fractured rocks grouting materials grouting methods high-pressure grouting

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Mechanical behavior and failure mechanisms of rock bolts subjected to static-dynamic loads

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International Journal of Mining Science and Technology 2024年第3期34卷 281-288页

作者： Hongpu Kang Guiyang Yuan Linpo Si fuqiang gao Jinfu Lou Jinghe Yang Shuangyong Dong CCTEG Coal Mining Research InstituteBeijing 100013China State Key Laboratory of Intelligent Coal Mining and Strata Control Beijing 100013China

This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal *** a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined *** experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain *** minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock ***,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support *** magnitude of this fortification is directly related to the plastic deformation induced by the *** findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.

关键词： Rock bolt Pretension Static and dynamic load Impact

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Theory,technology and application of grouted bolting in soft rock roadways of deep coal mines

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1463-1479页

作者： Hongpu Kang Jianwei Yang Pengfei Jiang fuqiang gao Wenzhou Li Jiafeng Li Huiyuan Chen Coal Mining Research Institute China Coal Technology and Engineering Group Co.Ltd.Beijing 100013China Coal Mining Branch China Coal Research InstituteBeijing 100013China State Key Laboratory of Intelligent Mining and Strata Control Beijing 100013China

The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured *** has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control *** article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its *** overview encompassed several key elements,delving into anchoring theory and grouting reinforcement *** new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also *** discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole *** examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was ***,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting ***,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable *** application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was ***,the existing problems in grouted bolting control

关键词： deep coal mine soft rock roadway grouted bolting rock bolt and cable grouting material high-pressure splitting grouting collaborative control technology

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The protective effect of icariin on glucocorticoid-damaged BMECs explored by microfluidic organ chip

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Chinese Chemical Letters 2022年第6期33卷 3177-3182页

作者： Tengqi Li Qingyu Zhang fuqiang gao Yadi Liu Wei Sun Yiyang Dong Department of Orthopedics Peking University China-Japan Friendship School of Clinical MedicineBeijing 100029China Department of Orthopedics Peking University Shougang HospitalBeijing 100144China Department of Orthopedics Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJi’nan 250021China Department of Orthopedics China-Japan Friendship HospitalBeijing 100029China Office of Academic Affairs Beijing University of Chemical TechnologyBeijing 100029China Department of Pharmaceutical Analysis College of Life Science and TechnologyBeijing University of Chemical TechnologyBeijing 100029China

Osteonecrosis of the femoral head(ONFH)is a devastating musculoskeletal disease characterized by the impaired circulation of *** purpose of this study was to explore the underlying mechanisms of the protective effect of icariin on the glucocorticoid-induced injury of bone microvascular endothelial cells(BMECs).Normal BMECs were extracted from the femoral heads by enzymatic isolation and magneticactivated cell sorting *** and icariin were used to intervene BMECs in microfluidic organ chips,and phalloidin staining was conducted to observe the cell morphology and *** next-generation transcriptome sequencing and real-time quantitative reverse transcription-polymerase chain reaction(q RT-PCR)were performed to identify the differentially expressed genes(DEGs)in different *** the microfluidic organ chip,it can be observed that after dexamethasone intervention,the filamentous structure in cell fibers disappeared and the cell morphology changed from spindle to round until *** could relieve these changes and showed a protective effect on glucocorticoiddamaged *** addition,201 DEGs were detected between the icariin protection group and the dexamethasone group,which were significantly enriched in 17 signaling pathways.8 of the top ten selected hub genes(IL6,PTGS2,VEGFA,etc.)were confirmed by q *** factors(TFs)-gene network showed 63 connections between 18 TFs and 12 *** instance,GATA2 could regulate 5 *** associations between 92 mi RNA and 12 DEGs were visualized in a mi RNA-gene *** hub mi RNA,has-mir-335–5 p was predicted to interact with 8 DEGs(PTGS2,VEGFA,etc.).Microfluidic organ chips could provide excellent morphological results for cell experiments,by which it could be observed that icariin showed a protective effect on the glucocorticoid-induced injury of ***,these DEGs,possible regulatory TF(GATA2,FOXC1,etc.)and mi RNA(has-mir-335–5 p)might be dysregulated in the ini

关键词： Osteonecrosis of the femoral head Bone microvascular endothelial cells Glucocorticoid Microfluidic chip Bioinformatic analysis

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Characteristics of evolution of mining-induced stress field in the longwall panel:insights from physical modeling

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International Journal of Coal Science & Technology 2021年第5期8卷 938-955页

作者： Jinfu Lou fuqiang gao Jinghe Yang Yanfang Ren Jianzhong Li Xiaoqing Wang Lei Yang Coal Mining Research Institute China Coal Technology and Engineering Group Co.Ltd.Beijing 100013China State Key Laboratory of Coal Mining and Clean Utilization(China Coal Research Institute) Beijing 100013China

The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of *** laboratory experiments have been conducted to investigate the stress *** study investigated its evolution by constructing a large-scale physical model according to the in situ conditions of the longwall *** analysis was used to reveal the mechanism of stress distribution in the *** modelling results showed that:(1)The major principal stress field is arch-shaped,and the strata overlying both the solid zones and gob constitute a series of coordinated load-bearing *** stress increasing zone is like a macro stress *** stress is especially concentrated on both shoulders of the arch-shaped *** stress concentration of the solid zone in front of the gob is higher than the rear solid zone.(2)The characteristics of the vertical stress field in different regions are significantly *** decreases in the zone above the gob and increases in solid zones on both sides of *** mechanical analysis show that for a given stratum,the trajectories of principal stress are arch-shaped or inverselyarched,referred to as the‘‘principal stress arch’’,irrespective of its initial breaking or periodic breaking,and determines the fracture *** is,the trajectories of tensile principal stress are inversely arched before the first breaking of the strata,and cause the breaking lines to resemble an inverted *** case of periodic breaking,the breaking line forms an obtuse angle with the advancing direction of the *** agreement was obtained between the results of physical modeling and the theoretical analysis.

关键词： Longwall mining Mining-induced stress field Physical modeling Principal stress trajectory Strain brick

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Course of major paravertebral vessels and the positional relationship to the vertebral bodies in healthy Chinese subjects： a CT-based study

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Chinese Medical Journal 2014年第22期127卷 3887-3893页

作者： gao fuqiang Zhao Xuanji Sun Wei Abhinav Pradhan Li Zirong Department of Orthopaedic Surgery China-Japan Friendship Hospital Beijing 100029 China

Background Several studies,including those done in China,report that paravertebral vascular injury during posterior spinal surgery can greatly harm patients,though it is a relatively rare ***,few studies have examined their course and anatomic relationship to the *** aim of this study was to measure the course of the major paravertebral vessels and their positional relationships to the vertebral bodies in Chinese subjects using computed *** We studied a total of fifty subjects who underwent thoracolumbar computed tomography from T1-S1 at our *** measured the theoretical distance,actual distance,theoretical angle,and actual angle of the paravertebral vessels at each thoracolumbar intervertebral *** The paravertebral artery actual angle at T4-L4 ranged from-11.41 to 79.75° and the actual distance from 16.98 to 52.53 *** actual angle of the inferior vena cava at L1-L5 intervertebral disc ranged from-40.75 to 34.50° and the actual distance from-36.63 to 61.69 *** was no significant difference in the actual angle of the paravertebral vein or in the actual distance in the thoracic segments according to gender （P ＞0.05）.However,the actual distance in the lumbar segments were significantly different according to gender （P ＜0.05）.Conclusions The major paravertebral vessels＇ course is closer to the mid-sagittal plane as they move posterior along the vertebrae,and the actual distance of the paravertebral artery and azygos vein increase,while the actual distance of the inferior vena cava *** course of the lumbar paravertebral vessels varies,especially at L4/L5,and may be more prone to intraoperative injury in female subjects.

关键词： spine major paravertebral vessels posterior approach surgery applied anatomy computed tomography

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